Sustainable Structural Design. Master s Thesis

Transcription

1 Sustainable Structural Design Master s Thesis Presented in Partial Fulfillment of the Requirements for the Degree Master of Science in the Graduate School of The Ohio State University By Joseph M. Danatzko Graduate Program in Civil Engineering The Ohio State University 2010 Thesis Committee Dr. Halil Sezen, Advisor Dr. Shive K. Chaturvedi

2 Copyright by Joseph Michael Danatzko 2010

3 Abstract Efficient energy use during construction and operation of buildings and sustainable building design are important issues in both modern society and the engineering community. Innovative methods are needed to address the environmental impact, energy use and other sustainability issues faced during planning and design of buildings. This study investigates sustainable design methodologies, the relationships between structural system and the 2009 Leadership in Energy and Environmental Design (LEED) rating system, the impact that project size and type can have on project sustainability, sustainable properties associated with construction materials (such as steel, cast-in-place concrete and prestressed/precast concrete) and computer programs aimed at determining the properties of sustainable structural design alternatives. This study investigates some sustainable structural design methodologies including minimizing material use, minimizing material production energy, minimizing embodied energy, life-cycle analysis/inventory/assessment and maximizing building reuse and presents their positive and negative sustainable qualities. This study discusses and reviews the categories of the 2009 LEED rating system in which points could be awarded to a project for sustainability of its structural frame. This study presents the role that project size and structural systemtype play on aspects of sustainable design including the design and analysis phase, land use, investments in sustainable technologies, use of timber as a primary load bearing material and other sustainable issues. This study reviews the structurally applicable sustainable properties associated with structural steel, cast-in-place and prestessed/precast concrete. Finally, this study provides a review of life-cycle analysis computer programs focusing on three (Building for Environmental and Economic Sustainability (BEES) v4.0, SimaPRO v7.1 and Athena Impact Estimator v4.0) aimed at assessing the sustainability of design alternatives. This study determined that no single current sustainable design ii

4 methodology can address all project sustainability issues at this time. Also, the LEED 2009 rating system does not reward projects for sustainable design of their structural systems in the same manner it does other aspects of design. It was determined that construction type and project size can have significant impact on sustainable opportunities for a project and that no single construction material is the most sustainable compared to others for all design types at this time. Finally, existing sustainability analysis software does not meet the current needs of its users in assessing design alternative sustainable properties and provides users with basic structural system comparisons, as exemplified by parametric studies using the Athena Impact Estimator v4.0. iii

5 Dedication I would like to dedicate this work to my grandfathers for their inspiration and the lessons they taught me: Joseph G. Inglese Michael Danatzko iv

6 Acknowledgements I would like to thank the following people for their help and guidance in life, civil engineering, career pursuits and opportunities, education and on this study: Dr. Halil Sezen, P.E. Dr. Shive K. Chaturvedi Dr. Hojat Adeli Dr. Caroline Merry Dr. Steven J. Kurtz, P.E. John C. Inglese A.I.A., P.E., LEED AP John Warren Nicholas R. Fisco Muhammad S. Lodhi Cindy Crawford Patrice Allen Diane Rano v

7 Vita Saint Peter s Preparatory School Engineering Intern/Drafting Assistant/ Drafter, Inglese Architecture and Engineering (East Rutherford, NJ) Civil Engineering Intern, Pennsylvania Department of Transportation (Allentown, PA) Civil Engineering Intern, Perini Corporation Civil Division (Newark, NJ) 2006 to Independent Study Lafayette College Steel Bridge Design Team, Lafayette College (Easton, PA) 2006 to Design Engineering Intern, Bohler Engineering (Warren, NJ) B.S. Civil Engineering (Minor: English), Lafayette College (Easton, PA) vi

8 2007 to Structural Engineer, Inglese Architecture and Engineering (East Rutherford, NJ) 2007 to Structural Engineer I, Washington Group International (Currently URS Washington Division) (Princeton, NJ) Consulting Structural Engineer, CDI Corporation (Contracted by URS Washington Division) (Princeton, NJ) 2008 to Graduate Research Assistant, Department of Civil and Environmental Engineering and Geodetic Science, The Ohio State University 2008 to National Student Steel Bridge Team Graduate Advisor, Department of Civil and Environmental Engineering and Geodetic Science, The Ohio State University 2009 to French Fellowship Recipient, Department of Civil and Environmental Engineering and Geodetic Science, The Ohio State University Field of Study Major Field: Civil Engineering Specialization: Structural Engineering vii

9 Table of Contents Abstract... ii Dedication... iv Acknowledgements...v Vita... vi List of Tables...xv List of Figures... xvi Chapter 1: Introduction Introduction Objectives Organization and Scope... 3 Chapter 2: Literature Review Sustainable Structural Design Methodologies Sustainable Structural Design of Tall Structures Leadership in Energy and Environmental Design Green Building Rating System Sustainability and Construction Type Sustainability and Construction Materials Review of Life-Cycle Analysis Computer Programs... 7 Chapter 3: Sustainable Structural Design Methodologies Introduction Methodology 1: Minimizing Material Use... 9 viii

10 3.2.1 Positive Sustainable Attributes of Methodology Negative Sustainable Attributes of Methodology Methodology 2: Minimizing Material Production Energy Positive Sustainable Attributes of Methodology Negative Sustainable Attributes of Methodology Methodology 3: Minimizing Embodied Energy Positive Sustainable Attributes of Methodology Negative Sustainable Attributes of Methodology Methodology 4: Life-Cycle Analysis/Inventory/Assessment Positive Sustainable Attributes of Methodology Negative Sustainable Attributes of Methodology Methodology 5: Maximizing Structural System Reuse Positive Sustainable Attributes of Methodology Negative Sustainable Attributes of Methodology Conclusions Chapter 4: Leadership in Energy and Environmental Design Rating System Introduction LEED Rating System Relative to Structural Design MR Credit 1.1: Building Reuse-Maintain Existing Walls, Floors and Roof Benefits of MR Credit 1.1: Building Reuse Disadvantages of MR Credit 1.1: Building Reuse MR Credit 3: Materials Reuse ix

11 Benefits of MR Credit 3: Materials Reuse Disadvantages of MR Credit 3: Materials Reuse MR Credit 4: Recycled Content Benefits of MR Credit 4: Recycled Content Disadvantages of MR Credit 4: Recycled Content MR Credit 5: Regional Materials Benefits of MR Credit 5: Regional Materials Disadvantages of MR Credit 5: Regional Materials MR Credit 7: Certified Wood Benefits of MR Credit 7: Certified Wood Disadvantages of MR Credit 7: Certified Wood Chapter 5: Sustainability and Construction Type Introduction Construction Type Wood Construction Design and Analysis Phase Investments in Sustainable Technologies Use of Wood as Primary Load Bearing Material Other Wood Sustainability Issues Steel and Concrete Construction Design and Analysis Phase Land Use x

12 5.4.3 Investments in Sustainable Technologies Building Materials Other Steel and Concrete Construction Sustainability Issues The Built Environment Conclusions Chapter 6: Sustainability of Construction Materials Introduction Structural Steel LEED 2009 and Structural Steel Structural Steel Section Production Recycled Materials Content and Structural Steel Other Sustainable Issues of Structural Steel Cast-in-Place Concrete LEED 2009 and Cast-in-Place Concrete Cast-in-Place Concrete Member Production Recycled Materials Content and Cast-in-Place Concrete Other Sustainable Issues of Cast-in-Place Concrete Prestressed/Precast Concrete LEED 2009 Sustainable Qualities and Prestressed/Precast Concrete Prestressed/Precast Concrete Member Production Recycled Materials Content and Prestressed/Precast Concrete Other Sustainable Qualities of Prestressed/Precast Concrete xi

13 6.5 Conclusions Sustainable Qualities and Issues for Steel Sustainable Qualities and Issues for Cast-in-Place Concrete Sustainable Qualities and Issues for Prestressed/Precast Concrete Chapter 7: Review of Life Cycle Analysis Computer Programs Introduction Building for Environmental and Economic Sustainability (BEES) v BEES v4.0 Program Outputs BEES v4.0 Sustainable Measurement Advantages BEES v4.0 Sustainable Measurement Disadvantages SimaPRO v SimaPRO v7.1 Program Outputs SimaPRO v7.1 Sustainable Measurement Advantages SimaPRO v7.1 Sustainable Measurement Disadvantages Athena Impact Estimator v Athena Impact Estimator v4.0 Program Outputs Athena Impact Estimator v4.0 Sustainable Measurement Advantages Athena Impact Estimator v4.0 Sustainable Measurement Disadvantages Conclusions and Program Highlights BEES v4.0 Program Conclusions SimaPRO v7.1 Program Conclusions Athena Impact Estimator v4.0 Program Conclusions xii

14 7.5.4 General Life Cycle Analysis Computer Program Conclusions Chapter 8: Modeling and Analysis with the Athena Impact Estimator v Introduction Modeling Parameters Athena Impact Estimator v4.0 Parametric Studies Study 1: Column Energy Consumption Study 1: Input Values Study 1: Analysis Study 1: Conclusions Study 2: Beam Energy Consumption Study 2: Input Values Study 2: Analysis Study 2: Conclusions Study 3: Concrete Suspended Slab Span Energy Consumption Study 3: Input Values Study 3: Analysis Study 3: Conclusions Study 4: Concrete Strength Energy Consumption Study 4: Input Values Study 4: Analysis Study 4: Conclusions Study 5: Concrete Fly-Ash Percentage Effect on Energy Consumption xiii

15 8.7.1 Study 5: Input Values Study 5: Analysis Study 5: Conclusions Concluding Remarks Chapter 9: Conclusions, Limitations and Recommendations Summary and Concluding Remarks Conclusions Limitations Recommendations References Appendix A1: Athena Impact Estimator Output Tables for Study Appendix A2: Athena Impact Estimator Output Tables for Study Appendix A3: Athena Impact Estimator Output Tables for Study Appendix A4: Athena Impact Estimator Output Tables for Study Appendix A5: Athena Impact Estimator Output Tables for Study xiv

16 List of Tables Table 3.1. Positive and negative sustainable attributes of sustainable structural design methodologies...19 Table 5.1. Sustainable design aspect qualities by construction type...41 Table 6.1. Structurally applicable sustainable properties of steel, cast-in-place concrete and prestressed/precast concrete as construction materials...57 Table 8.1. List of highlighted input labels and references...82 Table 8.2. Values employed for inputs in study Table 8.3. Total energy consumption values for study 1 as provided by the Athena Impact Estimator v4.0 for the applicable input variations...87 Table 8.4. Values employed for inputs in study Table 8.5. Total energy consumption values for study 2 as provided by the Athena Impact Estimator v4.0 for the applicable input variations...92 Table 8.6. Values employed for inputs in study Table 8.7. Total energy consumption values for study 3 as provided by the Athena Impact Estimator v4.0 for the applicable input variations...97 Table 8.8. Values employed for inputs in study Table 8.9. Total energy consumption values for study 4 as provided by the Athena Impact Estimator v4.0 for the applicable input variations Table Values employed for inputs in study Table Total energy consumption values for study 3 as provided by the Athena Impact Estimator v4.0 for the applicable input variations xv

17 List of Figures Figure 7.1. Screenshot of initial program screen for BEES v Figure 7.2. Screenshot of ratio weighting option offered by BEES v Figure 7.3. Economic performance graphical output for stucco, aluminum siding and trespa meteon comparison...62 Figure 7.4. Environmental performance graphical output for stucco, aluminum siding and trespa meteon comparison...63 Figure 7.5. Overall Performance Graphical Output for Stucco, Aluminum Siding and Trespa Meteon comparison...64 Figure 7.6. SimaPRO v7.1 product tree for 1.0 kilogram of cattle feed...67 Figure 7.7. SimaPRO v7.1 Graphical Output for One (1) Kilogram of Cattle Feed...68 Figure 7.8. Athena impact estimator v4.0 bill of materials report generic example...71 Figure 7.9. Athena Impact Estimator v 4.0 tabular output-generic example...72 Figure Athena Impact Estimator v 4.0 graphical output-generic example...73 Figure 8.1. Illustration of structure employed as generic model for Athena Impact Estimator v4.0 energy consumption assessment...79 Figure 8.2. Screenshot of initial input interface for a New project in Athena Impact Estimator v Figure 8.3. Screenshot of interface for Concrete Suspended Slab in Athena Impact Estimator v Figure 8.4. Screenshot of interface for Mixed Columns and Beam in Athena Impact Estimator v Figure 8.5. Screenshot of project assembly tree with project heading highlighted...83 Figure 8.6. Screenshot of Reports interface window with highlighted areas...84 Figure 8.7. Column height vs. total energy consumption at a live load of 45 psf...88 xvi

18 Figure 8.8. Column height vs. total energy consumption at a live load of 75 psf...88 Figure Live load vs. total energy consumption for columns...89 Figure Beam length vs. total energy consumption at a live load of 45 psf...93 Figure Beam length vs. total energy consumption at a live load of 75 psf...93 Figure Beam length vs. total energy consumption at a live load of 100 psf...94 Figure Live load vs. total energy consumption for beams...94 Figure Concrete suspended slab span length vs. total energy consumption...97 Figure Live load vs. total energy consumption for concrete suspended slab at span lengths of 15, 20, 25, 28 and 30-ft...98 Figure Concrete suspended slab concrete strength vs. total energy consumption..100 Figure Live load vs. total energy consumption for concrete suspended slab at concrete strengths of 3000, 4000 and 9000 psi Figure Gross floor area vs. total energy consumption at a live load of 45 psf Figure Gross floor area vs.total energy consumption at a live load of 75 psf Figure Gross floor area vs. total energy consumption at a live load of 100 psf Figure Live load vs. total energy consumption for concrete suspended slab fly-ash percentages xvii

19 Chapter 1: Introduction 1.1 Introduction In the modern engineering and architectural culture, sustainable design and energy efficiency have become paramount in design and application for architects, engineers and users as civic requirements and financial limitations mount. In all areas of civil engineering, engineers are encouraged to ensure that projects have the maximum lifespan for their intended use and employ the least amount of natural recourses (e.g., raw materials and energy required for their production) while still meeting client, economic, societal demands and code requirements. Two fields of civil engineering that are constantly assessing their ability to achieve sustainable goals are the engineering design and construction industries. The goal of these industries is to achieve lasting, environmentally sound solutions to the problems faced in the modern culture and look to achieve this in their design of new and rehabilitative projects. Achieving this goal requires the construction and design engineering communities to assess all the aspects and processes involved in a project. These aspects are can be varying and influenced by local conditions and the economy. They include but are not limited to; the required material production energies, design alternative maintenance requirements, material durability, recycled materials contents, project adherence to and applicability within sustainable rating systems such as LEED, structural system design methodologies, relation of sustainability to construction type, sustainability and construction materials and life cycle analysis modeling computer programs. Research into each of these areas contributes to determining methods for achieving high overall project sustainability. Various aspects of sustainable design and construction research have been and are currently being investigated. Research into the qualification and development of the sustainable properties of construction materials has been carried out in an attempt to 1

20 provide structural designers, planners and constructors with methods for optimizing the environmental impact of structural design. Research into the effect that structural form, system and magnitude have on building design relative to a structure s overall sustainable qualities has also been conducted to address the means and methods pertinent to all design phases (planning, design and implementation). Along with this research, rating systems such as the Leadership in Energy and Environmental Design (LEED) rating system must be assessed in various ways for their applicability to sustainable structural design. LEED is currently employed in the United States to grade various construction types on a credit weighted points system based on the environmental impacts each has across 13 categories typically associated with building design. While the LEED ranking system rewards construction projects (with little mention of structural system design) that meet its requirements, the engineering community looks to go further and better define the sustainable properties of all aspects of a project. This is illustrated by the construction materials production industry s effort to determine their economic and environmental impact more fully and achieve more sustainable designs. The aspects of a project s form, structural system and magnitude directly relate the issues facing both structural engineers and architects in attempts to achieve more sustainable structural designs. This study aims to present research on these aspects of sustainable structural design and illustrates the effect these issues have on structural systems. While structural design and sustainable structures hold many other key elements (such as material choice, life-cycle analysis, construction types and methodologies, etc.), this study focuses on the sustainability achievable in structural design and the nature of how it can directly relate to sustainability in the built environment. 1.2 Objectives The main objectives of this study are to: Present the roles of structure and structural design can play in project sustainability. Present the concept of sustainable structural design. 2

21 Present and discuss five sustainable structural design methodologies. Present and review the 2009 Leadership in Energy and Environmental Design Green Building document s applicability for structural system design. Present and review the role project size and material type play in structural and sustainable design. Present and discuss the role sustainability plays in three major construction materials (steel, cast-in-place reinforced concrete and prestressed/precast concrete). Describe and review the concept of life cycle analysis and its implication on structural design. Present and investigate the effectiveness of life cycle analysis computer programs aimed at assessing design alternative s sustainable qualities. Perform parametric studies use a LCA package program (the Athena Impact Estimator v4.0) to investigate the effects of columns, beams, slabs, concrete strength and fly-ash percentage on energy consumption and sustainable structural design. Present conclusions drawn from this study, limitations involved in this research and recommendations for future research. 1.3 Organization and Scope This thesis investigates sustainable structural design and provides background information and review of all concepts addressed. Chapter 3 presents the role structure and structural design play in overall project sustainability and the concept of sustainable structural design. This chapter also discusses five potential design methodologies to achieve sustainable structural designs. Chapter 4 presents and reviews the 2009 Leadership in Energy and Environmental Design Green Building document s applicability within project structural system design. Chapter 5 presents and investigates the role construction type plays in structural and sustainable design. Chapter 6 presents and reviews the role sustainability plays in three commonly used construction materials (steel, cast-in-place reinforced concrete and prestressed/precast concrete). Chapter 7 presents and reviews the concept of life cycle analysis and life cycle analysis computer 3

22 programs aimed at assessing design alternatives sustainable qualities. Chapter 8 presents parametric studies conducted using the Athena Impact Estimator v4.0 to assess issues of energy consumption in structural systems. This chapter addresses this by assessing the sustainability of columns, beams, slabs, concrete strength and fly-ash percentages via the Athena Impact Estimator v4.0 program output. Chapter 9 presents the conclusions drawn from this study, limitations involved in this research and recommendations for future research. 4

23 Chapter 2: Literature Review 2.1 Sustainable Structural Design Methodologies Sustainable design has been at the forefront of research in both the engineering and architecture communities for several years. Spurred by civic, monetary and political motivations, analysis of the effect that structures and construction has on the world around it has been conducted. Various researchers from numerous fields have worked to present the multifaceted world of sustainable construction and design and the methodologies, mindsets and practices associated with it. In the current building system design processes, structural engineers play a limited role in the overall sustainability of a design (Kestner 2007). While the contribution of sustainability to the built environment typically influences the architectural form of a structure, the performance and cost of a project drive the engineer s work and bottom line. While the building and construction community look to improve sustainable development through attention to integrated design and form, cost and structural performance must remain at the forefront of development (Jackson 2008 and Beheiry et. al 2006). Notwithstanding the merit of research into the sustainable properties of materials and the energy saving methodologies to overall sustainable design, previous research has illustrated that sustainable structural design relies on the proper implementation of structural form and systems. Also as suggested by previous research, the future of the built environment needs to account for more varied aspects of structure and construction (Smith 2007 and Horvath et al. 1998) Sustainable Structural Design of Tall Structures In a discussion on sustainable structural design, building size and magnitude play an integral part. As noted by Smith (2007), tall buildings can be considered sustainable structures in their very existence as they optimize the use of limited land resources. 5

24 Coupled with this are the increased loads, energy use, calculation time, etc. that are also associated with tall structures. For this reason, tall structures provide a platform to address how incorporating structural design and form with architectural desires and environmental constraints are keys to sustainable designs The design, construction, architecture and form of tall buildings each contribute to a structure s sustainable design. Each provide an illustration of the effects on sustainability that structural design can have outside of material choice and energy conservation. Sustainable structural design relies on designing structures that in their inherent nature within the built environment serve to enhance and provide to the existing infrastructure system. Tall buildings provide opportunities for sustainable structural design, as exemplified above, and through their place and use within both the general public s everyday life and engineering community. 2.2 Leadership in Energy and Environmental Design Green Building Rating System The Leadership in Energy and Environmental Design Green Building Rating System (LEED) is a tool employed by project designers to illustrate the effectiveness that their design choices can have on project sustainability. Developed by the United State Green Building Council (USGBC), the LEED 2009 rating system awards credits to a project for meeting outlined prerequisites and goals that are summed for a total point score under which a project s sustainable rating (silver, gold or platinum) is awarded. Design professionals petition the USGBC for the rating through an application process that requires detailed documentation of energy conservation efforts undertaken during the projects construction and operation. The USGBC publishes guidelines against which application for sustainable ratings are measured. The guidelines have been prepared for numerous construction types. This document provides and outline for the manner in which application for sustainable rating must be completed as well as guidelines and suggestions for meeting individual credit acquirements and goals. 2.3 Sustainability and Construction Type In structural design, the type of construction being undertaken by a project directly relates to its ability to achieve its sustainability goals. As the magnitude of a project and/or structure increase, its operating and embodied energy also increase. Due 6

25 to this, review of the effect that construction type (wood construction and steel and concrete construction) can have on the sustainable properties of a project is crucial to understand the role structural systems play in sustainability (Kestner 2007 and Szekely 1996). 2.4 Sustainability and Construction Materials Construction materials play a integral part in assessing the sustainability of any design alternative. Structural steel, cast-in-place reinforced concrete and prestressed/precast concrete each have unique qualities that contribute to the sustainability of a project. Good sustainable properties are associated with structural components that have low energy costs, high durability, low maintenance requirements and contain high-proportions of recycles materials (Naik 2008). The construction materials discussed each have their own positive and negative sustainable properties that have been reviewed from industry and research agency data. 2.5 Review of Life-Cycle Analysis Computer Programs This study looked to review the implementation of sustainable design concepts and methodologies in current life cycle analysis (LCA) computer programs. In an effort to assess the economic and environmental impact that design alternatives can have on a project, sustainability-modeling programs have been written. These programs attempt to assess the sustainability of design alternatives for comparison in an effort to determine the most sustainable option. Programs of specific interest in assessing structural design sustainability are the Building for Environmental and Economic Sustainability (BEES) v4.0, SimaPRO v7.1 and Athena Impact Estimator v4.0. These programs address the problem of sustainability measurement in various ways. 7

26 Chapter 3: Sustainable Structural Design Methodologies 3.1 Introduction A project s structural form, system and magnitude directly relate to the issues that its engineers and architects face when determining the most sustainable structural design alternative. This chapter presents research on numerous aspects and methodologies of sustainable design and illustrates their effect on structural systems. Structural engineers have various methods to design a structural element or system. From material choice to lateral force-resisting system, a structural system and its layout become a combination of the architectural form and engineering properties (two aspects that can often be at odds with one another.) This chapter assumes the goal of sustainable structural design to be the production of a structural system that meets the needs of the owner and user while minimizing the environmental impact and conserving resources where possible. From low/high-rise buildings to short/long-span bridges and any structure in between, minimizing project impact on natural resources and the environment is a goal of engineers, architects and builders alike. This chapter discusses some design methodologies for achieving this goal including: Methodology 1.) Methodology 2.) Methodology 3.) Methodology 4.) Methodology 5.) Minimizing Material Use Minimizing Material Production Energy Minimizing Embodied Energy Life-Cycle Analysis/Inventory/Assessment Maximizing Structural System Reuse Each design methodology has both positive and negative sustainable qualities. While each methodology has the same end goal, this goal is reached via different routes that can compete with one another and can have adverse effects either individually or combined on a successful sustainable structural design. It should be noted that these design methodologies, and the discussion herein, look to address issues concerning 8

27 structural, and not non-structural, members and construction materials. It is not the intention of this study to address the effect that non-structural members or materials can have on overall project sustainability. Therefore, for example, glass as a non-structural building material is not discussed in this research. 3.2 Methodology 1: Minimizing Material Use As presented by Moon (2008), total structural material minimization can be one goal of sustainable structural design. Engineers can achieve this in two ways. As suggested by Shi at al. (2009), combinations of various material types to form more efficient structural members and systems is one method by which the structural engineer can use the minimal amount of natural resources. Similarly, optimization of a structural model employing a single material type can be another method that reduces the amount of material employed in a design. Likewise, a project architect s methods for minimizing material use are two-fold. An architect can generate a building layout that produces the greatest amount of unusable space from the project site while allowing for all the functionality required by the structure s use. Contrary to this, an architect can minimize building material by making the layout itself as efficient as possible for intended structural use, but without producing the maximum amount of usable space (Trabbuco 2008). While in many cases the proposed building layout achieves the maximum usable space, the second method looks to employ layouts that maximize use-productivity while the first attempts to maximize usable space. Minimizing material use is one sustainable design methodology that can be achieved separately by architects and engineers. This design methodology achieves the goal of sustainable design producing structures that can perform as required while being as structurally efficient as possible Positive Sustainable Attributes of Methodology 1 Research into this topic has included evaluation of similar building systems with varying heights to determine and quantify the increase in the amount of material associated with each layout. Also, research on lateral force resisting systems has been conducted to determine their impact of the total material use (Moon 2008, Shi et al. 9

28 2009). A structure employing the minimal material can achieve the goal of a sustainable design as it has the least impact on the natural environment through lower raw material use. Also, this methodology can affect the structural engineering community to develop more efficient and innovative design processes using the least amount of materials. As a result, engineers may need to evaluate and improve the current conventional design concepts and practices to determine the most efficient manner to achieve designs with the minimum amount of materials Negative Sustainable Attributes of Methodology 1 While the end goal of least impact on natural resources is achieved, the analysis and design time associated with these methods can be computationally high. The additional computation time required is due to the complexity involved in solving structural optimization problems or systems with multiple material types interacting. The increased complexity may require that more construction drawings with greater detail must be provided to contractors following the design phase. In short, more calculations and greater complexity take the engineer more time to complete and require more drawings. In addition, a structural design optimization to the use the minimum amount of materials may not be the most sustainable design as construction issues or needs require additional resources. A project s approvals process becomes longer as the number of drawings and details increase. This process may also lead to disputes between architect, engineer and owner as minimal changes by one may require complete redesign by the other. Although new tools such as Building Information Modeling (BIM) can reduce the amount of time and effort needed to modify a design, simple revisions to a complicated design still require time. Following the design process, the construction duration of the structure also increases as well as the time required for scheduling and labor due to increased design complexity. Along with this, there may be increased need for design construction clarifications, such as requests for information (RFIs), as complexity of the design increases. All of these possible negative aspects are likely to adversely affect the total project cost. 10

29 3.3 Methodology 2: Minimizing Material Production Energy Apart from the design of the structural system itself, a methodology for structural sustainability involves reducing the amount of energy and natural resources required for the production of construction materials. For all construction materials (cast-in-place reinforced concrete, prestressed concrete, steel, wood, masonry, etc.) there exists a production energy cost. This cost can vary from year to year, and by location, and can be the result of the world market and environmental regulation requirements. Sustainability enters the material production process mainly during the evaluation of the energy costs required in the gathering, refining, and mixing (etc.) of raw materials. Along with this, sustainability in this methodology relies on the reduction of overall energy costs that can be made to produce materials with the same, or similarly structurally useful, material properties as current production methods. This methodology calls for engineers to designate the use of or specify structural elements that employ production-energy efficient materials in their designs. It also calls on the respective industries to best quantify their energy uses and work to improve current energy costs and production methods. Along with this, industries should seek the development of new technologies and processes for material generation. Another critical aspect of this methodology calls for the reduction and monitoring of material generation by-products and emissions (Naik 2008) Positive Sustainable Attributes of Methodology 2 Researchers and industry experts have been working in recent years to quantify both the positive and negative effects of construction materials from a sustainable viewpoint. By providing and compiling data on the energy expenditures associated with construction material production, energy values can be tied to sustainable material properties. In achieving a sustainable structural design, this methodology can be advantageous in its attempt to conserve natural recourses and reduce by-products and emissions. Also, studying and providing material production energies to design professionals may lead to innovations in design as the relation between material strength and the energy required for its construction can be determined. In short, as the industry and engineers more fully define construction material properties, the sustainability of 11

30 structural systems will increase Negative Sustainable Attributes of Methodology 2 While the correlation between increased sustainability and minimization of material production energy may seem evident, this is not the case. As the materials themselves may increase structural system sustainable properties, this does not mean that the structural system itself will achieve its most sustainable configuration. Inherently, when the selection of one construction material for use in a structure is made (whether it includes the most sustainable properties or not), the structural system s ability to be sustainable becomes limited. For example, with the selection of special moment resisting reinforced concrete frames as a lateral force resisting system in a structure, the possibility of a more sustainable configuration coming from a design that could include masonry shear walls or steel moment frames is negated. While this can be combated with designs that include combination of different construction materials, use of other materials than the most sustainable construction material would thus decrease the structural system sustainability from a raw materials conservation viewpoint (Shi et al. 2009). Additionally, while the manufacturing industry works to achieve sustainable products, this methodology does not address the input of building industry to sustainable structural design (Deane 2008.) Thus, it falls solely to the manufacturing industry and the engineer to produce greater structural sustainability. 3.4 Methodology 3: Minimizing Embodied Energy As suggested by Trabucco (2008), the design of an efficient service core is probably the most challenging aspect of a tall building project. While his focus is on tall buildings in this statement, the methodology he is referring to can be extended to all structures. The embodied energy associated with a structure is a result of its intended use, initial design and life span. These aspects relate the energy associated with construction to the energy associated with the operation and maintenance over the structure s life. The concept behind minimizing embodied energy is an effort made on both architect and engineer s parts to assess the energy cost of construction versus the 12

31 operational energy expenditure. Structural layouts that follow this methodology require both engineer and architect to generate designs that focus on reducing the energy use within and around the building. Also associated with this is the design of a structure from a service core standpoint with the goal of balancing building use with façade design (Trabucco 2008). This methodology offers opportunities for sustainable designs to be generated as the focus becomes more on the effective use of the natural environment (regional thermal qualities, geothermal wells, waste recycling systems, wind turbines, solar panels, etc.) to reduce the energy associated with a structures operation. This methodology also addresses the idea of maximizing a structure s thermal mass qualities, harnessing energy use in structural motion and adaptable structural systems (Moon 2008). The methodology also looks to achieve the goal of a sustainable structural system by possible inclusion of adjacent structures in the design or dividing the design of a single structure to multiple smaller structures to allow for a more efficient setup (Shi et al ) Positive Sustainable Attributes of Methodology 3 This methodology focuses on achieving sustainable structural design through attention to both the service core and the structure s façade. The minimization of embodied energy requirement is achieved through analysis of both the service core and façade to determine the competing qualities each can have on overall structural sustainability. Ideally, this methodology will result in a structure that attunes the form both structurally and architecturally finding a balance between both to reduce the structures energy envelope. In doing so, the structural system will increase project sustainability through allowing for a consideration of various sustainable properties (including but not limited to: thermal properties, natural light, utilization of solar panels/wind turbines.) Negative Sustainable Attributes of Methodology 3 The minimizing embodied energy methodology typically neglects maximizing the efficiency of the structural system. Analyzing the structure from a total operating energy envelope viewpoint, the methodology limits its users to define the design by the manner in which it can most effectively utilize the ambient energy available to it. In doing this, a 13

32 design may not efficiently use its structural materials, which in turn can decrease its overall sustainability. Also, in areas with a lesser-built environment than dense cities, facades that utilize available ambient qualities may reduce the architectural appeal or functionality of a structure relative to the existing infrastructure (Wood 2007). This methodology is also directly tied to location and regional limitations due to the effectiveness of certain technologies (geothermal wells, waste-recycling systems, wind turbines, solar panels, etc.). 3.5 Methodology 4: Life-Cycle Analysis/Inventory/Assessment A common tool employed by design professionals to assess and quantify the sustainability of a project is the Life-Cycle Analysis (LCA). Similarly employed are the Life-Cycle Inventory (LCI) and Life-Cycle Assessment (LCAs) analysis methods. These tools are often employed to justify or qualify the net-cost to benefit ratio or economic impact of a design decision. Designers and engineers have worked to employ these models (outlined by ASTM standards E , E , E , E , E and E ) to determine the sustainable properties of various aspects of the structural system. These standards define the methods to identify and evaluate multifaceted aspects of a decision involving various measures. Both designers and owners see the LCA/LCI/LCAs as tools to generate the most sustainable design by evaluating its monetary value and constructability requirements. By assessing a structural design through a multifaceted view, the increased number of measures employed along each step increase the accuracy of the evaluation and allow for the most sustainable design to be achieved (Horvath 1998). This is achieved by including and balancing a greater number of aspects of the design (e.g., not solely minimizing material amounts) and will produce a more sustainable design. This methodology has been employed in various projects (Laefer et al. 2008) both related and unrelated to sustainable design and reviewed for case studies to assess its accuracy. Thus, it has merit as a design tool/methodology for sustainable structural design Positive Sustainable Attributes of Methodology 4 The most notable advantage of LCA/LCI/LCAs, when employed for structural 14

33 sustainability purposes, is that they provide designers and owners with a clear outlook and picture of what their structure can achieve during its lifetime. This means that projects with low initial construction costs can assess their estimated energy use over building life considering both environmental and economic impacts. Also, buildings with high initial construction costs can determine viability of sustainable technologies relative to their payback periods. Along with this, LCA/LCI/LCAs models call for greater inclusion by all representative parties on a project, allowing for varied input and cross-discipline interaction. This interaction and input can only help to further the design and lead to greater overall sustainability through more effective designs, decreased design time, increased construction speed and less energy use and maintenance requirements during the lifetime of the structure. Also, through widespread use within industries, this methodologies/models can help to increase efficiencies throughout the built environment and provide a greater knowledge bank for future design as development continues (Horvath 1998) Negative Sustainable Attributes of Methodology 4 Notwithstanding the positives aspects discussed above, the most lauded negatives to LCA/LCI/LCAs are accuracy with which they can be implemented and completed. Inherent in all of the ASTM standards applicable to LCA/LCI/LCAs is the inclusion of both risk and uncertainty in the analyses. This uncertainty is driven by poorly or obscurely defined factors. This has led to many analysis methods that have produced controversial results (Horvath 1998). While the goal of this methodology is to inform designers so as to generate more sustainable designs, much of this information may not be accurate enough or unknown at the time of initial design to achieve the goal of sustainability. Varying costs, shifting deadlines, durability of materials, long term maintenance requirements and factors not related to the structural system can lead to LCA/LCI/LCAs results that misinform the designers and thus lead to designs that are not the most structurally sustainable. It should also be noted that while increasing the accuracy of the LCA/LCI/LCAs model might be a solution to inaccurate or misleading reports, this 15

34 increased accuracy does not guarantee a more effective description of overall sustainable structural system properties. This means that even an accurate model may not efficiently contribute to describing design alternative sustainable properties and thus serve useless to project designers. The LCA/LCI/LCAs methodology is a prominent method for assessing many aspects of a project. However, the uncertainty can be very high in its application to the structural system and its sustainability. Also, as with the Methodology 1, minimal design changes can have adverse effects on the structural sustainability and the methodology s accuracy and may require entirely new models. 3.6 Methodology 5: Maximizing Structural System Reuse The concept behind maximizing structural reuse is to generate layouts and designs that produce the least amount of solid waste at end-of-life or allow for the greatest amount of whole or partial system and/or structural component reuse. This two-pronged methodology is similar in idea to the concept of minimizing material use but differs in the type of design it produces. As opposed to the most material efficient design, the objective of this methodology is to achieve layouts that allow for various structural uses, longer structural life spans and to address the possibility of structural element reuse during the planning and initial design stage. Coupled with this initial concept of this methodology is the idea that solid waste management is a key to, and opportunity for, enhanced sustainable design (Laefer 2008.) This concept of solid waste management can extend to waste during all phases of design, construction and demolition, and involves an assessment of all materials included in each part/phase. However, the main goal of the structural reuse methodology is for architects and engineers to achieve greater sustainability through the design of structures by investigating multiple uses of the same structural. This methodology has grown out of observations on the cost associated with demolition and the waste it produces compared with the financial incentive or prolonging building life. Also, this methodology focuses more on the end-of-life of a structure and calls on the engineer to assess material types and structural elements considering their possible reuse in the initial structural system design. This methodology aims to combat 16

35 the rapid technological developments and higher standard of living in the twenty-first century and the negative that this increased expansion can have on the infrastructure as suggested by Laefer (2008). This methodology also suggests that standardization of connections and structural elements that allow for more versatile structural systems will produce higher levels of sustainability within those systems Positive Sustainable Attributes of Methodology 5 As pointed out by Laefer (2008), total or partial building reuse is a solution that contributes to both direct financial gain and environmental sustainability. The methodology of maximizing building reuse is clearly captured by this statement. In relation to sustainability, building reuse and initial design for multiple intended uses is a key factor as its outcome is reduced waste and need for less raw materials. The possible reuse of a structure may have financial incentives as the owner has the ability to reoccupy the building for a new use, which in turn extends the service life of the structure. Also, this design methodology calls for initial architectural design that attempts to involve a structure s adaptation to its surrounding environment and reduces the amount of renovations required for future structural reuse. This methodology could also lead to innovation in both the architectural and engineering communities by employing similar design layouts that allow for relocation of partial structural systems between project sites or possible structural element reuse. Each of these aspects can increase the sustainability of a structure and are possible advantages of this methodology Negative Sustainable Attributes of Methodology 5 Multiuse structures often inherently produce sustainable structural designs, as they are versatile and efficient in their use of available space. Incorporating various functions for a design can result in less functionality for the primary structural use. While this may seem a small price for increased sustainability, generating a multiuse structure may not necessarily produce the most sustainable structural design for the original intended use. In short, the design may not be as efficient as it could have been if a single use structure had been maintained. Also, while structural element reuse from one structure to another can lead to fewer raw material requirements for future construction, close inspection of and accurate 17

36 qualification of structural members must be completed before reuse. The advantage of reusing a structural element over the cost of qualifying a subsequently unsafe member may result in higher initial project costs and reduce the sustainability of the second structure (Laefer 2008). 3.7 Conclusions Each methodology presented herein looks to achieve the same goal, the most sustainable structural design, through different means and measures. Table 3.1 provides a summary of the positive and negative sustainable attributes that each methodology present. 18

37 Methodologies Positive Sustainable Qualities Negative Sustainable Qualities Longer design and analysis time Least impact on natural Greater structural system environment complexity Methodology 1: Minimizing Material Use Methodology 2: Minimizing Material Production Energy Methodology 3: Minimizing Embodied Energy Methodology 4: Life-Cycle Analysis / Inventory / Assessment Methodology 5: Maximizing Structural System Reuse Lower raw material requirements May lead to innovative designs and practices Research currently being conducted Conservation of natural resources By-product reduction May lead to innovative designs that assess strength and sustainability properties simultaneously Consideration of both sustainable form and function Focus on operating energy use Attention to "service core" during design Considers sustainability over project life Greater inclusion of representative project parties Encourages cross-discipline interaction Widespread use can lead to quicker innovation Financial incentives Extended service life Design relative to surrounding built environment May lead to innovation in standardized designs More drawing and details required Longer approvals process Construction complexity Higher total project cost May not be "most" sustainable design Limitations to sustainability from material choice Currently lacking input from building industry Can result in less efficient structural system Design limited to most effective use of ambient energy Surrounding built environment can limit methodology Highly sensitive to location/region Model accuracy Risk and uncertainty included in analyses Other sustainable issues can detract from most sustainable structural design Adverse effects from minimal design changes Possibility for decreased primaryuse functionality Structural element reuse inspection required Table 3.1. Positive and negative sustainable attributes of sustainable structural design methodologies 19

38 Chapter 4: Leadership in Energy and Environmental Design Rating System 4.1 Introduction Dwindling natural resources, environmental changes, financial limitations and the global community have produced a climate in which modern civic growth requires the attention, commitment to and promotion of environmentally sound design and construction practices by the public and private sector. In response to this, the United States created the Green Building Council (USGBC) in 1993, which serves as an organization aimed at assessing and quantifying the environmental impact of new, existing and rehabilitative projects. The USGBC has developed several rating systems for these projects while also working to address different project development and delivery processes. These rating systems and processes provide users with outline for various development and construction types (e.g., schools, neighborhood development, retail, etc.) and are referred to as the Leadership in Energy and Environmental Design (LEED) for those project types and are continually updated. To address both new and rehabilitative construction, the USGBC developed the LEED Green Building Rating System for New Construction and Major Renovations (USGBC 2008). This document serves as an outline for engineers, architects, developers and contractors of the means and methods by which sustainable designs can be achieved in the planning, construction and operational phases of building projects within the LEED Rating System s guidelines (with 2009 being the most current edition.) The code describes that the LEED Rating System is composed of five distinct design areas each requiring various prerequisites and including 49 separate categories in which up to 100 points can be achieved by construction applying for accreditation. The 2009 LEED document provides design professionals with the intent, requirements/options and potential technologies and strategies for each prerequisite and category. The use of and adherence to the requirements outlined in the document during the design process is at 20

39 the discretion of the architect and/or engineer and often due to requests made by either party or the owner. 4.2 LEED Rating System Relative to Structural Design The 2009 LEED Rating System for New Construction and Major Renovations provides its user with the opportunity to achieve up to 100 rating points. Each of these points is attainable under different sections of the code and relate to various aspects of the design process and choices. Many of the rating points available to a new or rehabilitative construction project are directly related to the project magnitude, location and whether it is to be new or rehabilitative construction. Due to this, the structural system of a project can greatly affect its sustainability. While the code offers various ways in which a sustainable design can be achieved under the 2009 LEED Rating System, it is limiting in how structural frame system can increase a project s sustainability. As a result, the structural engineer (while a part of the planning phase of the project) has little room within the current code to suggest and affect a project s LEED rating. However, most of these limitations are directly related to the size of the project and the complexity of the structural system required as governing load cases can directly affect structural system material choice. Nonetheless, these limitations can restrain a project from achieving the most sustainable design possible and provide structural engineers and designs with little room to affect whole building sustainability. Upon reviewing the 2009 LEED Rating System for application within the structural frame design in new construction, five categories offer possible opportunities for the structural engineer to contribute to the sustainability of the project. These five categories are all located within the Materials & Resources design area of the document and include; MR Credit 1.1: Building Reuse-Maintain Existing Walls, Floors and Roof, MR Credit 3: Materials Reuse, MR Credit 4: Recycled Content, MR Credit 5: Regional Materials, and MR Credit 7: Certified Wood. While the 2009 LEED Rating System offers numerous instances where rating points can be obtained in other areas of a project, the above categories offer the opportunity for structural system choices to directly affect the LEED rating a project can obtain. This chapter provides a review of these categories and illustrates their effect on 21

40 sustainable structural design through discussion of both their positive and negative aspects MR Credit 1.1: Building Reuse-Maintain Existing Walls, Floors and Roof The 2009 LEED rating system awards up to 3 points under MR Credit 1.1: Building Reuse. These points are awarded based upon the total percentage of building reuse as documented during planning and construction. The intention of this credit according to the 2009 LEED document is, to extend the lifecycle of existing building stock, conserve resources, retain cultural resources, reduce waste and reduce environmental impacts of new buildings as they relate to materials manufacturing and transport. The document outlines that 1 point can only be obtained with a minimum of 55% building reuse increasing to 2 and 3 points at 75% and 95%, respectively. The 2009 LEED rating system suggests the reuse of existing building elements as well as the removal of elements that impede increased sustainable building operation Benefits of MR Credit 1.1: Building Reuse The building reuse credit offers the opportunity for both financial and sustainable gains for a project. Its intention is to encourage the reuse of significant portions of an existing structural system that can be incorporated into new construction, employed for an alternative building use from that of the original design intention or updated to comply with more current building codes for existing use. Each of these applications offer structural engineers the opportunity to affect the sustainable qualities of a project in positive ways with regard to the LEED rating system. Through the incorporation of existing structural elements into new construction, the LEED rating system provides a structural engineer with the opportunity to present applicable design alternatives to other project parties. While this opportunity may require more in depth structural analysis and the detailed assessment of the existing structural frame, by offering these credits the USGBC encourages innovative design approaches that allow a structural engineer to provide direct input to sustainable properties of a project. If the project calls for maintaining the existing frame while expanding a structure to include new construction, the structural engineer can present structural system design alternatives that employ the existing structural frame. Using engineering 22

41 practice and knowledge, any new structural elements can be designed to function as efficiently as possible with the existing frame. Similarly, if a project called for a structure to provide an alternative use from the original design, structural engineers are offered the opportunity to affect the project s sustainable rating by suggesting design alternatives that maintain as much of the existing structural system as possible. Through the addition of new structural elements to the existing frame, upgrading of specific connections or other required structural system additions, the project can maintain its existing frame but achieve the goal of an alternative use. Also, this credit encourages new construction and design that focuses on layouts that can allow for alternative future uses. Again, the structural engineering community is offered an opportunity to affect project sustainability, as defined by LEED. Finally, if a project calls for the continued use of a structure with qualification for existing design codes or increased loads, structural engineers can affect project sustainability by suggesting design alternatives and analysis approaches that look to alter the existing system as little as possible. Efficient connection design and innovative member strengthening methods are just two of the proposals that the structural engineer can make. All of these suggestions are examples of how, within the 2009 LEED rating system parameters, structural design can affect a project s sustainability rating Disadvantages of MR Credit 1.1: Building Reuse While the above examples describe how structural load carrying system choice in a project can affect the overall sustainability, this LEED credit has limited applicability. As noted by the credit name, this credit can only be obtained by projects that look to employ an existing system and not new construction. This credit is also limiting by the manner in which building reuse is suggested and measured. By requiring that at least 55% of the existing structure be maintained, design alternatives are limited to those which incorporate more than half the existing structure and LEED 2009 does not reward what may be more sustainable designs that do not reach this benchmark. Also, this credit rewards the reuse of existing building frames that may result in overall designs that might produce less sustainable layouts than their new counterparts. However, the most glaring omission in this credit is that there is no relation of alternative new/existing design to 23

42 actual sustainable properties such as production and/or operational energy. Each of these shortcomings illustrate that this credit, while allowing for relation of the structural system to sustainability, may not serve to create the most sustainable design but may increase the sustainability of a project as defined by LEED MR Credit 3: Materials Reuse The 2009 LEED rating system awards up to 2 points under MR Credit 3: Materials Reuse. These points are awarded based on the percentage of Reused Materials as documented during planning and construction. The intention of this credit according to the 2009 LEED document is, to reuse building materials and products to reduce demand for virgin materials and reduce waste, thereby lessening impacts associated with the extraction and processing of virgin resources. The code outline that 1 point can be obtained with a minimum of 5% reused materials increasing to 2 points at 10% with no further reward in increased percentages. The document suggests that materials should be salvaged where possible and that potential reused material suppliers be researched as well Benefits of MR Credit 3: Materials Reuse The material reuse credit is aimed directly towards reducing the amount of raw materials for construction elements required by a project. By reward material reuse from an existing structure, LEED 2009 encourages investigation by the project team into designs that look to reuse as many of the existing construction elements as possible. Also, this credit supports plans for reuse of existing structural elements between two projects. Hence, a project team can investigate if other surrounding projects have resources that might serve in their design and incorporate them into project planning and development. This credit allows for the structural engineer to have a direct effect on project sustainable qualities by suggesting and developing designs that achieve layout allowing for easier reuse of sections. Also, by investigating existing systems for their lateral and vertical force resisting capabilities, the structural engineer can affect project sustainability through the reuse of existing systems or through creative designs that incorporate existing sections with new ones. This credit reward can provide a stepping-stone for structural 24

43 engineers to affect sustainable design through innovative designs and structural systems that may not have been considered in preliminary design Disadvantages of MR Credit 3: Materials Reuse The greatest pitfall that this credit has is the requalification of existing structural members. While a member s reuse may be preferable to a new design, care must be taken to ensure that the condition of the member is such that its material properties have not been drastically altered from its initial use. If a project plans to reuse a member, it must first meet the criteria for reuse within the new structural frame according to the current applicable building code. However, if after testing or evaluation of the member it is shown to no longer have the necessary material properties, the resources required for that requalification must be absorbed by the project financially and can affect how sustainable the project can now be. It may occur that a design calling for reuse of several structural members from an existing frame may no longer retain the required material properties resulting in a redesign of the new structural frame. Also, the existing members that are not sufficient will require replacement with new members resulting in what might be a lower overall sustainable rating. Along with this, the relatively small number of points awarded by the 2009 LEED rating system for this credit in relation to the total possible points a project can achieve may not warrant the detailed design that may be required. Also, these same points can be achieved by reuse of existing architectural fixtures and other mechanical systems. By not providing a greater reward to structural systems that reuse elements, pursuit of this credit by the project team does not mean that the most sustainable structural design will be achieved MR Credit 4: Recycled Content The 2009 LEED rating system awards up to 2 points under MR Credit 4: Recycled Content. These points are awarded based on the percentage of Recycled Content included in building materials as documented during planning and construction. The intention of this credit according to the 2009 LEED code is, to increase demand for building products that incorporate recycled content materials, thereby reducing impacts resulting from extraction and processing of virgin materials. The code outlines that 1 25

44 point can be obtained with a minimum of 10% recycled content increasing to 2 points at 20% with no further reward in increased percentages. The document suggests that project should establish recycled content materials goals and consider a range of materials attributes with selecting products and materials Benefits of MR Credit 4: Recycled Content Encouraging the use of construction materials with increased recycled contents is an effective way to reduce the volume of raw materials employed in material production. This credit fosters sustainability by rewarding the selection of construction materials with recycled content and provides an avenue for project teams and structural engineers to directly affect a building s LEED Sustainability rating through structural frame choice. It can also be noted, as further described in Chapter 6 of this document, that high-rise structural frame construction materials such as steel and concrete employ recycled content and research into each materials sustainable qualities is conducted and fostered by their respective industries. Another benefit of this credit is potential use of byproducts, such as fly ash and slag in concrete as a replacement for cement. Research has shown positive results indicating that concrete strength can increase through the use of these admixtures. Also, fly ash and slag are usually readily available industrial byproducts. This availability also illustrates their applicable sustainable qualities as they reuse existing byproducts for new material production. These admixtures are one example of research being conducted and any admixtures employed in concrete production look to relate both production costs and sustainability. Researchers look to achieve this by defining the material properties of cement and concrete mixes relative to their sustainable properties for their effective use as construction materials. Relating the sustainable qualities of these materials to their material properties can serve to better inform project teams and structural engineers to more effectively develop and suggest structural frame designs that achieve this credit. This may also lead to the design of structural systems that achieve low production energy and raw material consumption relative to alternate designs Disadvantages of MR Credit 4: Recycled Content From the perspective of a project s structural frame, this credit may not go far 26

45 enough to encourage the most effective and encompassing sustainable design. These two credits can be achieved by a design through the selection of concrete design mixtures or steel that provides the required recycled material content. By making the only requirement for this credit be that the materials include recycled content, this does encourage research into alternative layouts or designs by the project team. Simply, as long as the material has the required material content, the points can be obtained regardless of whether or not an alternative material design would have resulted in a structural system that would have greater sustainable impact. As outlined in greater detail in chapter 6, as the recycled content of materials increase, the required production energy of those materials can also increase and produce high concentration of byproducts. From this, it can be observed that the production energies and byproducts associated with high-recycled content materials can yield a negative effect on the total production/construction energies required for a project. Therefore, the selection of one material over another, and the subsequent reward by the LEED 2009 rating system, may not increase the overall sustainability of a project in relation to total energy expenditures and byproduct generation for production and construction. Current research into the material properties of high-recycled content cements has illustrated that while strength can be increased through their use, ductility and durability may decrease at high contents. Research also indicates that this material may have limited application. While the decision for high-recycled material content concrete would need to be made on a project-by-project basis, the research indicates that it may best serve a structural system not to employ this material MR Credit 5: Regional Materials The 2009 LEED rating system awards up to 2 points under MR Credit 5: Regional Materials. These points are awarded based on the percentage of Regional Materials included in building materials as documented during planning and construction. The intention of this credit according to the 2009 LEED document is, to increase demand for building materials and products that are extracted and manufactured within the region, thereby supporting the use of indigenous resources and reducing the environmental 27

46 impacts resulting from transportation. The document outlines that 1 point can be obtained with a minimum of 10% of the total project materials cost being regional materials and increasing to 2 points at 20% with no further reward in increased percentages. LEED 2009 suggests that a project should establish locally sourced materials goals and consider a range of materials attributes with selecting products and materials Benefits of MR Credit 5: Regional Materials The Regional Materials credit encourages a project to consider use of building materials and suppliers within a 500 miles radius of the project site. This credit can have several positive effects on the sustainability of a project. First, encouraging the use materials located within the radius can help to minimize the both transportation costs and environmental impact. Most notably, if the shipping route that a building material must take to a site can be minimized, the environmental impact of that material can be mitigated. As a result, a project can increase its sustainable environmental effects while contributing to the project s financial bottom line. Second, the use of regional materials can have positive effects on the regional economy and encourage growth both economically and technologically. By rewarding projects that aim to maximize regional materials use, LEED can affect an increase in material production in that area. If a project employs regional materials, it can work with local producers to ensure that any other attainable LEED credits can be achieved through their use. Thus, a project can encourage a local producer to investigate technologies that reduce their byproduct emissions or utilize designs including higher recycled materials contents or any other applicable LEED credit. This can serve to make the producer more attractive as a supplier for future projects, leading to increases in both current and future projects sustainability. Finally, regional materials can also contribute to sustainability by allowing and encouraging a project to be similar in form and design to the surrounding built environment. This can encourage designs that both architecturally and structurally mimic similar projects already in use. This LEED credit can therefore encourage a project to pursue designs that can incorporate the intended use with those of the surrounding built 28

47 environment and thus contribute to that environment in a more sustainable fashion Disadvantages of MR Credit 5: Regional Materials Inherent in the selection of any design or building material is the limitation that specific design or material choice comes with. These limitations can have an effect on the overall sustainability of a structure. For example, if a project were to select cast-inplace concrete as its primary structural frame building material, that project s design could thus be limited by whatever layouts or configurations that building materials would allow. This limitation could mean that an alternative design that chose steel for its primary structural frame may have more (or less) sustainable qualities for the selected design. While this can be said about all projects, the use of regional materials and the reward that LEED gives for it can be limiting to decisions made for design and may not result in the most sustainable overall project. If a project were to pursue this credit for its structural frame and select an applicable building material that was within the 500 mile radius and obtain this LEED credit, this does not mean that the lowest possible material production byproducts would be generated by that choice. If an alternative material were selected from a producer outside that radius did not award this credit, it is possible that lower production energies and environmental impact could be achieved. Therefore, the choice by a project to pursue this credit may have negative effects on the overall project sustainability contrary to the positives that it might gain for its LEED rating. From the perspective of a project structural system and its relation to all the other building materials included nn a project, this credit can be obtained without its consideration. If the selected materials for a project s interior or exterior construction were regional materials, this LEED credit may still be obtained with no consideration of regional material use for structural load carrying system. This would seem to be at odds with this credit s intention as the necessary percentages for the credit points could be achieved without consideration of a structural frame and could limit the effect that a structural engineer can have on project sustainability MR Credit 7: Certified Wood The 2009 LEED rating system awards 1 point under MR Credit 7: Certified 29

48 Wood. This point is awarded based on meeting the requirement that 50% (based on cost) of a project s wood based materials are certified according to the Forest Stewardship Council s criteria for wood components. The intention of this credit according to the 2009 LEED document is, to encourage environmentally responsible forest management. LEED suggests that project should establish a project goal for certified wood use and ensure proper installation and that all materials are quantified Benefits of MR Credit 7: Certified Wood Through this credit, LEED is encouraging project designers to pursue and ensure the use of specific wood products, that are renewable compared to other building materials due to their natural growth, in design. By employing of certified wood in design, designers can look to increase overall project sustainability and decrease the effect on the use of raw materials associated with other building materials. This credit also has the byproduct of promoting certified wood production and encouraging expansion in that field. As projects seek to obtain this credit, supply of sufficient material must be made available and can encourage the increased production in a region as building demand increases. Thus, this credit can help to bolster local and/or regional economies and encourage innovation and expansion in the area of certified wood production Disadvantages of MR Credit 7: Certified Wood In consideration of a project s structural system, this credit may play little role in increasing its sustainability as the economical use of wood as a primary structural system material decrease with increase project height and the subsequent increase in design loads. Also, the use of wood as a structural load carrying system can be limited by its durability and service life. From the perspective of a structural engineer and a project structural system material choice, this credit does little for large projects. While projects with generally lower structural loads can achieve the use of wood as a primary structural system element, the increase in height of a structure and loads can limit the ability of wood to be utilized in an economical manner. Due to this, building materials such as steel and concrete are typically chosen for structural system for their ability meet required 30

49 structural performance at these higher loads. Therefore, this credit may have little effect on projects that must meet structural design requirements for medium to high-rise and long-span structures. Similar to other LEED credits, the certified wood credit requirements can be met through the use of building materials other than the primary structural system. If a project that did not employ wood as the primary structural system element was to designate that all partitions must be constructed of certified wood, this credit may still be obtained. While this may be viewed as a positive for the project and its LEED rating, this does not mean nor encourages that the overall project is the most sustainable choice or layout possible. Structural engineers are limited in being able to meet the requirements of this credit for two reasons. First, the use of wood as a primary structural element may not be available as an economical choice or from a durability, maintenance and service life. And second, this credit can be achieved elsewhere devoid of the structural engineer s input. 31

50 Chapter 5: Sustainability and Construction Type 5.1 Introduction type can greatly affect the sustainability of structural systems. As discussed in Chapter 4, the 2009 LEED rating system can limit the ability of a project to achieve the most sustainable design possible while still reaching a high LEED rating. Also introduced was the concept that project size (the total height of structure) can affect the overall sustainability through the increased design and analysis period that larger structures can require. However, overall project sustainability may not be directly related to project size and/or height. As a project s size increases, structural system complexity can also increase due to factors including, but not limited to, design loads increase. Due to this, larger projects often encounter limitations in the form of structural system material strength requirements. As a result, primary load bearing systems in these projects require materials with higher strength properties (such as steel, cast-in-place concrete and prestressed/precast concrete). This limitation can have significant effects on the design and performance of a structure. 5.2 Construction Type This chapter classifies the sustainability of projects under two construction types: wood construction (allowing for the use of wood as the primary load carrying material) and steel and concrete construction (employing steel and/or concrete as the primary load carrying materials). For this discussion, these references will be employed throughout. Both construction types offer opportunities to achieve a sustainable design and have qualities that illustrate the structural system s role in a sustainable design. 5.3 Wood Construction As defined earlier, wood construction allows wood to be used as the primary 32

51 load bearing material. This type of construction has various effects on the design of a project and its ability to achieve and implement sustainable measures. In this section, some of the aspects affecting project sustainability and the structural system design are discussed Design and Analysis Phase Inherent in any project involving new and/or rehabilitative construction is the design and analysis phase. This phase includes, but is not limited to, design and analysis of the proposed structure. Design and analysis for any new construction can have varied lengths for completion and is closely related to building layout and architectural design. In wood construction, values for design loads are often lower than their steel and concrete construction counterparts. This is mostly due to the intended use and smaller size of the structure. As a result of this, the amount of time required for the design and analysis phase to be completed on wood projects is usually shorter than steel and concrete construction projects. With a shorter design and analysis phase, more energy, effort and project budget can be allotted to research into sustainable technologies and systems that can be employed during the projects construction and operational phases Investments in Sustainable Technologies As mentioned in the previous section, wood construction has the advantage of a shorter design and analysis phase. Similarly, wood construction can also have a shorter period between initial planning and building operation, namely, a shorter construction phase. This means that the time between initial owner investment and revenue generation is shorter than its steel and concrete companion. Thus, the shorter construction phase that wood construction has a shorter payback period and can result in a sustainable technology providing a more economical investment. This shorter payback period also has the advantage of providing engineers and architects with a financial incentive that can be attached to a proposed sustainable design. By being able to link financial and sustainable properties in a design, the designers of low-rise construction projects can have a greater effect on project sustainability Use of Wood as Primary Load Bearing Material Another sustainability benefit of wood construction is in its use of wood as a 33

52 primary load bearing material. A project that employs wood frame construction has the sustainable advantage of using a rapidly renewable building material. Typical steel and concrete construction materials, such as steel and concrete, require more raw materials than wood. Also, the production energies required for steel and concrete construction materials are greater than those for wood. Along with this, current sustainability rating systmes (such as LEED), provide an incentive for the use of wood as a building material. From these three aspects, wood can be viewed as a more sustainable alternative to other construction materials Other Wood Sustainability Issues Contrary to the positive sustainable qualities of wood as a building material is the lack of attention that a wood construction projects structural system can receive. Through the selection of wood as the primary building material, a wood construction project can meet design code requirements. However, the selected wood design may not be the most sustainable alternative for the project. If an alternate design involving steel or concrete as the primary frame was to be selected it may result in a longer project service life and greater durability. These are just two of several sustainable advantages that and alternate design may provide. This illustrates the fact that while wood construction often achieves high sustainable ratings and provide opportunities to the project team to suggest sustainable technologies, the final product may not be the most sustainable alternative. Along with this, another sustainability issue that can be unique to wood construction is energy use. In any construction project, the service core (the operational and maintenance energy required for the project) and its function must be taken into account. Inherently, the service core of a project is dependent on the project s size. For example, the amount of energy and power required for a wood construction residential structure compared to a steel and concrete construction residence (assuming the same project site) can be very different. This difference drives the design of interior layouts in both high- and wood construction and the manner with which operational and maintenance efficiency issues are addressed. With a smaller service core relative to a steel and concrete alternative, a wood construction project can be afforded the 34

53 opportunity to achieve a lower total embodied energy. The relationship between embodied energy and service core in the wood project alternative can allow engineers and architects to employ technologies that may work only for smaller scale projects. Thus, a wood construction project may be able to achieve greater energy efficiency than a steel and concrete alternative, assuming both are on the same site and with the same intended use, due to the difference in building size and service core energy use requirements. This can also be related to project structural system design as the use of wood as a construction material can afford a project with advantageous thermal qualities and opportunities that may not be achievable in a steel and concrete construction project. 5.4 Steel and Concrete Construction As defined earlier, steel and concrete construction employs steel and/or concrete as the primary load bearing material. This type of construction has various effects on the design of a project and its ability to achieve and implement sustainable measures. In this section, some of the aspects affecting project sustainability and the structural system design will be discussed Design and Analysis Phase Similar to wood construction, the design and analysis phase can play a major part in a steel and concrete construction project. As steel and concrete construction projects often have higher design load values, they must rely on stronger materials such as steel and concrete. Also, analysis of a steel and concrete construction alternative often produces governing loads that vary between members throughout the structural system. For example, while the overall design of a steel and concrete project can determine that it is controlled by its seismic response loads, this does not mean that the design of certain elements are not controlled by other loading scenarios. The increased number of design controlling load combinations on elements can require greater engineering effort and a longer period required for design relative to a wood construction alternative. This can have both positive and negative effects on project sustainability. With more complex structural systems comes the opportunity for design innovation that may achieve higher overall project sustainability. However, this 35

54 increased effort required for design may draw project funds away from other sustainable efforts resulting in a lower overall sustainable rating. From this, it becomes clear that complexity of a project s structural system can lead to difficulties in its ability to achieve a higher sustainable rating Land Use Inherent in a steel and concrete construction project is a sustainable quality that cannot be achieved in wood construction. With stronger structural materials, steel and concrete construction projects can be built taller than a wood alternative. Thus the design of any steel and concrete construction makes efficient use of project site (especially in areas where land is expensive, i.e., downtown of major cities) that cannot be achieved by a wood construction alternative. By increasing the overall height of a project, the useable space increases. Efficient use of allowable project space is a sustainable quality that looks to meet and/or exceed the requirements of the current project. By doing this, the overall sustainability of the project can be higher as it can serve or house more occupants. For example, construction of a five-story hospital instead of a two-story one would make more efficient use of the limited resource of space Investments in Sustainable Technologies Opposing the positive sustainable qualities of steel and concrete construction can be the financial limitations it imposes on sustainable technologies. With more complex building designs and larger structures, additional monetary limitations can occur. Due to this, investments into sustainable technologies can prove to be financially unsound as their payback period can be much longer than in wood construction. Combating this is the idea that economy of scale can take over and that numerous efficient technologies can result in greater overall system efficiency. Each of these points illustrates that sustainable technologies can affect steel and concrete construction projects sustainability in significant ways. However, sustainable technologies in steel and concrete construction can also limit overall project sustainability. One limitation can be due to project budget constraints that limit what technologies might be implemented. A second limitation 36

55 comes from involving numerous technologies (such as roof gardens or reflective façade surfaces) that may interact negatively. If a project cannot install more sustainable systems due to cost restrictions, it can result in an overall less sustainable structure than its wood construction counterpart. Likewise, investing in numerous technologies can result in a system not interacting efficiently or leading to higher future maintenance costs. Both of these reasons illustrate that sustainable technologies play a different role in steel and concrete construction Building Materials Steel and concrete construction projects are those that employ steel and/or concrete as the primary construction material. This means that either steel, cast-in-place concrete or precast/prestressed concrete sections serve as primary load carrying members. Each of these building materials have unique qualities that can help a project to achieve a high sustainable rating and will be discussed in a later chapter. However, some general observations can be made about the role that these building materials play in a project s overall sustainability relative to their wood alternatives. The above materials have advantageous strength qualities that lead to their selection as construction materials. From a sustainability perspective, each of these material choices makes efficient use of space as their design intention is to resist the required load with as little cross-sectional area required. This can allow for greater usable space. These materials are also well established within the construction industry for use. This has led to both past and current research into the sustainable properties of these materials and methods by which they can be employed in a project layout and interact with project facades in sustainably advantageous ways. Similarly, in an effort to increase sustainable properties, research into and the implementation of new production methods and technologies have been included to increase material use by their respective industries and reduce required production energies and byproducts. Along with this, research into the use of industrial byproducts (fly-ash, slag, etc.) and recycled materials contents on the strength properties of these materials have also and are currently being conducted. 37

56 While the ability of steel, cast-in-place concrete or precast/prestressed concrete to achieve higher sustainable properties as construction materials through the means listed above varies, it can be concluded that their use in high-rise construction can have advantageous sustainable impact on a project. However, other limitations and issues can affect this Other Steel and Concrete Construction Sustainability Issues Another sustainable advantage that steel and concrete construction projects can achieve is the ability of larger projects to include multi-use or future-use functions into their layouts and to reuse structural elements or partial structural systems. In the design of these systems, designers look to achieve various goals. In a multi-use project, design layouts that foster, promote and provide the means by which a project can successfully achieved multiple uses are presented. For example, a structure that provides an underground parking area, street level business layouts and residences above looks to capitalize on the ability to provide shopping, covered car parking and housing in one location. The above example can increase a project s sustainability as the inclusion of these essentials would require less environmental impact than housing that was further from shopping areas requiring residents to transport both themselves and their purchases. By reducing the need for these additional trips, a project can increase its sustainability. Similarly, a future-use project looks to provide designs and layout that allow for various occupancies. For example, if in the initial project design, care is taken to ensure that the provided layout achieves both the original intention of an office layout as well as allowing for minimal to no remodeling requirements for conversion to a residence, building service life can be extended. This can increase project sustainability and marketability as the additional future use can provide a longer revenue stream to recoup sustainable investments as well as mitigate or remove demolition costs for future construction. Both of these designs types also provide sustainable advantages through the efficient use of sections (by extending their service life) and by reducing raw materials requirements for future use. Also afforded to steel and concrete construction design is 38

57 the opportunity for section or partial structural system reuse. Steel and concrete construction projects require materials with greater strength properties than wood and thus employ more raw materials for their production. Structural elements made of these materials (steel and concrete) involved in steel and concrete construction can come at a premium cost due to world markets. Due to this, investigation into the reuse of either single structural elements or partial structural systems can be a viable alternative in modern construction projects. This is a sustainable quality that can only be achieved in steel and concrete construction and thus plays a role in overall project sustainability and initial project planning and design phases. 5.5 The Built Environment The surrounding built environment is an issue in steel and concrete construction projects looking to maximize building height. Local municipalities can impede a project from achieving the most sustainable design by imposing restrictions on heights, distance from roads, façade design, etc. While a project can apply for a variance, there is no guarantee that it will be approved. For example, if a project s surrounding architecture were limited to heights of 40 feet, a new structure that might serve its occupants more efficiently with a design height of 60 feet cannot be pursued, possibly affecting overall structural sustainability. Similarly, if a project looks to decrease its operating energy through the use of glass in an area where codes limit buildings to only masonry facades, overall project sustainability can be negatively affected. Both of these examples illustrate that factors other than construction type can affect a project. As displayed above, a steel or concrete structure can provide a more sustainable alternative in areas where land-use is paramount by allowing for greater structural height. Combating this sustainable property is the surrounding built environment and the effect that that it can have on design. In areas with predominantly steel and concrete construction with greater height, other building design effects, for example unique wind loading due to a tunneling effect, must be taken into account leading to additional design and analysis time. In areas with predominantly wood construction with lower heights, proposed steel and construction steel and concrete construction projects that are higher may be able to take advantage of thermal energy but, 39

58 in the process, may impede the ability of surrounding projects to do the same. Each of these areas can affect total building sustainability and point to the role that the surrounding built environment can play in a project s design. 5.6 Conclusions This chapter displays that both construction type and structural design play a role in various aspects of a project. Table 5.1 provides an outline of the advantages offered by steel and concrete and wood construction types as defined in this chapter. 40

59 Design Aspect Wood construction Steel and Concrete Construction Design and Analysis Phase Less design complexity Shorter period required for design Shorter period between design and construction Lower total project energy requirements Availability of additional investment into sustainable technologies More experience within industry Greater design complexity Longer period required for design Longer construction period Greater total project energy requirements Less funds for investment in sustainable technologies Less experience within industry Land Use Less efficient land use Use of land more efficiently Investments in Sustainable Technologies Use of Wood as a Primary Load Bearing Material Shorter payback period for sustainable investments Greater economical incentive for designers and owners Great ability for efficient interaction between multiple sustainable technologies Wood is a renewable resource Advantage in structural system cost LEED incentives for use of wood May not be most sustainable design alternative Building life issues Longer payback period for sustainable investments Possibility for "economies of scale" in sustainable technology use More issues in efficient interaction between multiple sustainable technologies Use of wood not an option Require less sustainable construction materials No explicit LEED incentives Greater ability to meet multi- or future-use needs Less project life issues Other Sustainable Issues Lower operating energy use requirements Ability to use small scale technologies to advantage Possible advantageous thermal qualities relative to other construction materials Longer revenue stream possibilities Greater material reuse after demolition possibility Section or partial structural system reuse Table 5.1. Sustainable design aspect qualities by construction type 41

60 Chapter 6: Sustainability of Construction Materials 6.1 Introduction The materials selected by a project can greatly affect overall project sustainability. The primary construction materials discussed in this chapter are steel, cast-in-place concrete and prestressed/precast concrete. These materials have various individual sustainable qualities and their use in a structural load carrying system can have unique effects of project sustainability. Presented herein is a review of each of these primary construction materials for their individual sustainable qualities, byproducts associated with their production, production energies required for member fabrication/construction and issues surrounding their use and application as sustainable materials along with a summary of positive and negative sustainable aspects of each. Along with this, issues included in the construction methods and limitations imposed by each are presented. 6.2 Structural Steel The use of structural steel as a primary structural system material has been widely employed in various construction projects in United States and around the world. This is due to the advantageous material properties that steel possesses and its ability to be employed in varying design layouts. Research has been conducted to investigate its applicability as a sustainable building material, the energy, methods and byproducts associated with its production and the effect of recycled materials contents. The design and construction of steel has been and continues to be outlined by the American Institute of Steel Construction (AISC 13 th Ed.). This section discusses sustainable properties of steel and provides examples LEED 2009 and Structural Steel While many of the sustainable properties of steel are associated with the technological advances made in industry and in its production methods, qualities other 42

61 production energy requirements can contribute to the sustainability of steel relative to cast-in-place and prestressed/precast concrete sections. Steel sections have the ability to be reused as construction materials as one project reaches its end-of-life. This ability for section reuse means that it is also possible for the reuse of partial structural systems between projects. These qualities can contribute to a higher LEED sustainability rating, possible advantageous financial outcomes for a project and a lower environmental impact. As described in Chapter 4, the 2009 LEED sustainable rating system rewards projects that reuse existing sections or existing structural systems under MR Credit 3: Materials Reuse. This credits aims to encourage the reuse of these structural sections or partial systems between projects for two reasons. First is the goal of reducing transportation costs for construction materials to a project site. Second is the goal of reducing the depletion of natural resources. Both of these goals can be achieved through the use and reuse of steel as a construction material and can contribute to overall project sustainability. Along with the 2009 LEED rating system credits rewarded for the reuse of sections that steel can offer a project, reuse of sections can offer significant financial gains. Be reducing transportation and new sections costs, additional funds can be employed to pursue other sustainable technologies and increase total project sustainability. Likewise, the additional saving can make the choice of steel as the primary structural system material more attractive to project owners, which can have a positive effect within the construction industry. It should be noted that construction costs for steel can vary between regions with varying labor costs. However, the section reusability may be able to offset this aspect for a given design and encourage steel use outside of typically non-steel-use regions. Similarly, partial structural system reuse can have the positive financial aspect of prolonging building service life and reducing construction costs. For example, if and existing steel frame consisting of six floors were to be partially demolished preserving the lower three floors for an alternate use, a project could greatly decrease their construction and labor costs as well as possibly contribute to new construction from the 43

62 out-of-service elements of the original project. Also, partial structural system reuse can be achieved through the use of steel as a building material through addition or removal of members to existing frames. This can be illustrated in two ways. First, if a project were to convert a braced steel frame to a moment resisting frame, façade improvements, such as additional storefront window space, may now be possible allowing for a new structural system use. Also, if a project explored a design alternative that called for the construction of a new frame that would be connected to an existing frame, minimal changes may be required to the existing frame that would only be possible in steel construction. Both of these examples can contribute to the overall sustainability of a project as well as provide financial incentive by reducing the required amount of new materials and construction costs relative to new construction. As referenced earlier, the reuse of steel sections between local projects and the reuse of partial structural systems can provide environmental advantages to a project. Two key aspects of new steel section production are the energies required and the emissions that occur during production. New steel generation can be an intensive process requiring various types of thermal and electrical energy. Associated with this energy are any byproducts involved in its generation, most specifically green-house-gasses (GHGs). With various inputs involved in energy generation for mining of raw materials, conversion of existing materials into usable materials for new sections and transportation of materials to production facilities, quantifying the total energy and byproducts associated with production can be difficult. In addition, the mixing of necessary materials and the resulting chemical reaction to achieve useable grade steel also has its own GHGs emissions. These points illustrate that reuse of sections and partial systems within structures can contribute greatly to reducing the environmental impact of steel as a construction material. Reuse of steel between projects requires qualification of existing steel sections for further use. While the 2009 LEED document rewards the reuse of sections or partial systems, analysis and testing must be conducted on sections to ensure that there has been no degradation or compromise of their strength and deformation properties. For example, if the section or part of the section buckled or yielded, it may not be reusable. Also, the 44

63 same section or system, while possibly designed following earlier building standards or codes, must be ensured to perform as required by the current code. For this reason, a project must take into account that while section reuse may be an option, investment may be made into requalification of these sections and system. The additional cost associated with this testing and analysis can hurt a project financially and use of new steel materials may be advantageous from both financial and sustainable points of view. Therefore, a project may decrease its overall sustainability if it were to investigate the reuse of sections or a system to find that new materials were required. Also, a project that investigated reuse options unsuccessfully would invest time, financial assets and energy into section testing and analysis that could result in an increase in overall project environmental impact Structural Steel Section Production Production energy requirements for steel can be difficult to fully quantify as numerous variables and units of measure exist across the inputs required for new section production. According to data published by the United States Department of Energy (USDOE 2009) an estimated 16.3 MBtu/ton were employed in the production of steel. This publication references data provided to the USDOE from industry and includes only values associated with electricity, natural gas and coal use relative to the various steel production methods. The data provided by industry for this publication does not address the environmental impact from power generation nor the impact of the chemical reactions associated with the production of steel. Illustrated by the non-inclusion of other energy requirements, such as those involved in raw material mining, environmental data provided from industry doe not provide a full definition of the energies and emissions in steel section production. This lack of a full definition can limit the use of steel as a construction material as its advantageous for section reuse over new section production cannot be fully described. In essence, the sustainable advantages that steel can provide to construction are directly tied to its ability to be easily reused as well as the financial and environmental cost associated with its production Recycled Materials Content and Structural Steel 45

64 As outlined in Chapter 4, the 2009 LEED rating system rewards project that incorporate building materials containing recycled materials into their construction. Steel provides a project with this option as the percentages of recycled materials included in new steel production have been increasing over recent decades. Research by both industry and academia has displayed that recycled materials content has little effect on strength properties associated with steel sections as well. Also, recycled content has no significant effect on steel section durability (Horvath 1998). This recycled material content is an advantage to both projects and producers as it can minimize the need for additional raw materials for section production. As indicated by the United States Department of Energy publications, recycled materials content can increase required production energies relative to the various steel production methods (USDOE 2009, Eruchan 2002). As noted above though, there exists a lack of fully defined energies required for recycled materials contents including all energy and environmental costs associated with section or material recycling. This limits the ability to fully define the effects recycled materials contents can have on material sustainability Other Sustainable Issues of Structural Steel The use of steel as structural load carrying system choice can provide a project with advantages that may not be possible with other materials. Its strength and ductility properties have made it a preferred material choice for many current and past projects. It also offers other possible sustainable advantages such as streamlined construction schedules and lower construction waste production. For example, unlike other construction material types, steel construction does not require formwork, which can reduce the overall waste produced and energy required for construction. Also, with planning, construction speed of a project can increase, as steel structural elements do not require any time between placement and function in steel construction. In essence, in a steel construction project, as members are placed they can carry load. This means that a project does not have to wait a period of time for sections to reach their required strength properties. It should also be noted that each of these advantages might have positive financial benefits that would encourage owners and project managers to pursue steel construction and contribute to available funds for other sustainable technologies. 46

65 Each of the positive sustainable qualities provided above may depend on accurate predictions of production energy requirements and byproducts. To achieve a clear understanding of the use of steel as a construction material relative to others, care must be taken by a project team and industry to assess the impact the steel has. While sustainable advantages can be achieved through its use, these advantages rely on accurate life-cycleanalysis (LCA) and life-cycle-cost modeling (LCC). Included in these models should be accurate forecasts of production energy requirements, byproduct emissions and operational and maintenance costs. 6.3 Cast-in-Place Concrete Cast-in-place concrete construction has been employed for a wide range of construction projects. As a construction material, it offers the opportunity for projects to achieve complex designs and provides engineers with and opportunity for variations within structural layouts that other construction materials may not. Regional financial restrictions and labor costs have driven the use of cast-in-place concrete construction throughout the United States and the world. Cast-in-place concrete construction and the concrete production industry are both highly skilled and developed professions with vast project experience and knowledge. The design and construction of cast-in-place concrete has been and continues to be governed by the American Concrete Institute with input from the Portland Cement Institute. This section addresses the LEED 2009 sustainable qualities, production, recycled materials content and other sustainable issues associated with cast-in-place concrete construction. Where applicable, examples for these topics will be provided as well as an outline of the positive and negative sustainable properties that cast-in-place concrete can provide to a project if selected as the primary building material LEED 2009 and Cast-in-Place Concrete The LEED 2009 credit applicability to the aforementioned construction materials often overlaps between points that can be obtained. While this is most often applicable to MR Credit 4: Recycled Content, MR Credit 3: Materials Reuse becomes more difficult in cast-in-place concrete construction. The intention of the LEED credit as applied to a project s structural system, as provided in Chapter 4, is to encourage the reuse of existing 47

66 structural elements or systems. For cast-in-place concrete construction, this task can be very complex. The removal and testing of an element may be possible with cast-in-place elements provided care is taken during deconstruction. For example, the removal of a cast-in-place concrete beam would require that beam-column joints be severed between all adjacent beams and the supporting columns. This would mean that any reinforcing steel placed through a connection would require either cutting or demolition that would leave the connection reinforcing intact. If the reinforcing bars were cut, the existing section would require further design for permanent connections in a frame, which could lead to either more waste or construction difficulty. If the joint reinforcement were maintained, a project would be required to ensure that sufficient strength was developed between the connection of existing member and new construction. This would again require further design and possible construction issue. Therefore, reuse of cast-in-place concrete members, as described here, is very unlikely and difficult. As illustrated in the above example, although difficult, it may be possible to reuse cast-in-place concrete components. However, to assess the sustainability of this construction, a project must consider the construction energy required and design time necessary for the member s reuse as well as any other sustainable issues related to it. Also, similar to the reuse of steel sections, design professionals would need to address the strength and other material properties of the existing member. It is possible that a member may be tested and determined to no longer be functional for reuse in a new structural system. This shows that reuse of a cast-in-place concrete component between two projects may require greater financial assets, construction, demolition and preparation time and analysis relative to entirely new construction. Unlike MR Credit 3: Materials Reuse, MR Credit 4: Recycled Content can benefit the overall sustainability of a cast-in-place concrete project as well as its LEED 2009 ranking. Concrete construction, in general, has similar qualities to that of steel construction in that new member production can be achieved including recycled materials. Also, similar to steel, concrete section offers the opportunity for a project at its end-of-life (demolition phase) to reuse materials from demolished structure to be employed as recycled content for new elements. This means that a project could increase 48

67 its overall sustainability by employing members that include recycled materials contents as well as planning for the reuse of their demolished sections as raw materials for new construction. While pursuing this opportunity in new construction is possible, the only reward currently provided to projects in the LEED 2009 rating system is for their use of recycled materials. With concrete reuse may be viewed as a materials reuse issues and fall under MR Credit 3 of the LEED 2009 rating system, the current document intention does not encourage this. Other recycled materials content effects will be discussed in a later section Cast-in-Place Concrete Member Production The sustainable properties associated with the production of a cast-in-place concrete member are centered on the production of the concrete, and specifically cement. Reinforcing steel may also be an important factor contributing to sustainability of the member. Also, construction methods associated with concrete placement can contribute to its sustainable properties and are discussed in a later section. Driving the sustainability of cast-in-place concrete sections are the energy intensive aspects of cement and concrete production including raw material gathering and byproduct emissions that are associated with both. While three of the four raw materials in concrete (water, sand and gravel) are abundant and renewable resources, the fourth (cement) is the single most critical material affecting the byproduct emissions, environmental impact and sustainable properties of concrete. The mining and gathering of raw materials for the production of cement requires various forms of energy. In addition to this initial energy, additional energy is required to generate usable cement mixes from these raw materials. Illustrating the energy and raw material requirements of cement production, it has been shown an average of 1.6 tons of raw materials are required to produce 1.0 ton of cement (Naik 2008). This high amount of input energy and raw materials are combined with byproduct outputs that include CO 2, NO x and other green house gasses. Along with this, additional energy input is required for mixing of cement and other raw materials for concrete production also producing CO 2. Upon review of the production requirements of concrete elements, it becomes clear that its production requires various energy inputs during its various stages of 49

68 production. Consequently, production energy associated with concrete members can vary and are related to their production facilities and raw material availability. The measures of these focus on cement or concrete production facilities themselves and do not include the various other energy requirements associated with concrete production (e.g. raw material mining, transportation and carbon emissions associated with it, etc.). Due to this, an accurate and normalized required energy value for concrete production per volume is difficult to obtain. The concrete industry tries to reduce the energy and environmental impact of concrete and cement production through the use of pozzolanic and recycled industrial materials. Materials, including but not limited to, silica fume, slag and fly ash are often used to replace cement in concrete design mixes in an effort to increase the sustainable and material properties of concrete. The addition of these pozzolanic materials can reduce the total amount of raw materials required for cement production and typically increase the strength of concrete. However, in both cement and concrete, these materials can affect the required production energies and may lead to higher energy input requirements Recycled Materials Content and Cast-in-Place Concrete Concrete construction can provide several opportunities for recycled materials content. Similar to steel, the concrete industry and research institutions have investigated the use of industrial byproducts, such as fly-ash and slag, in construction and production (Pentalla 1997). Along with these industrial byproducts, research has been conducted into the use of demolished concrete sections as aggregates and raw materials for new production (Petalla 1997). This research has displayed various material properties such as the possibility to make gains in the mix design strength and construction functionality. However, this same research has indicated that at higher recycled material concentrations, concrete mixes can have increased brittleness (Pentalla 1997). As mentioned earlier, an increase in the recycled materials content of a concrete mix can yield and increase in the required production energy. While this increase can play a role is analyzing design alternatives, the use of recycled materials can increase the overall sustainability of a project. 50

69 6.3.4 Other Sustainable Issues of Cast-in-Place Concrete Cast-in-place concrete construction can offer projects unique opportunities in terms of scheduling. While cast-in-place concrete construction requires time after placement for initial member strength to be achieved, streamlining of construction schedules can be achieved. With proper planning, a project may be able to increase its construction speed and decrease financial costs. While a streamlined construction schedule can aid a project, the time required between concrete placement and hardening of cast-in-place concrete elements can be limiting. Unlike its steel and prestressed/precast counterparts, cast-in-place concrete sections do not possess the ability to be loaded upon initial placement. This limitation can have impact throughout all phases of a project. By limiting the load that can be placed on a section during construction, the design and analysis phase may not be able to pursue designs that employed these members in temporary use. For example, a project that employs a partially completed portion of the structural frame as a support for loads associated with temporary storage on an upper floor may not be able to carry that load until the cast-in-place section met the required strength. The volume of construction wastes generated also affect the sustainability of construction. The required formwork and associated materials necessary for a cast-inplace concrete frame must also be taken into account during whole project sustainability assessment. While a project may be able to achieve high sustainable ratings through the intelligent use of thermal energy in its design, these ratings may not offset the wastes produced during construction. 6.4 Prestressed/Precast Concrete Prestressed/precast concrete construction offers projects unique sustainability opportunities in both design and construction. Among these is the ability to achieve better material quality control not available in cast-in-place concrete construction due to greater control during the casting process. This allows for project designers to consider layouts not possible with other construction materials. As with the other construction materials discussed in this chapter, research has been conducted by both industry and academia into the sustainable qualities that prestressed/precast concrete possesses as well 51

70 as investigations into newer production methods and materials (Deane 2008 and Laefer 2008). As an alternative to cast-in-place and steel construction, prestressed/precast concrete construction can allow a project to increase its overall sustainability in terms of both environmental and financial aspects. The design of a prestressed/precast concrete structure is typically governed by the American Concrete Institute (ACI) and Precast Concrete Institute with additional information provided by the Portland Cement Institute. This section addresses the LEED 2009 sustainable qualities, production, recycled materials content and other sustainable issues associated with prestressed/precast concrete construction. Where applicable, examples for these topics are provided as well as an outline of the positive and negative sustainable properties that prestressed/precast concrete can provide to a project if selected as the primary building material LEED 2009 Sustainable Qualities and Prestressed/Precast Concrete Prestressed/precast concrete construction offers projects the opportunity to address two of the sections of the LEED 2009 rating system. These two sections are MR Credit 3: Section Reuse and MR. Credit 4: Recycled Materials Content. Prestressed/precast concrete construction provides a project with the opportunity to investigate the reuse of existing members from a previous project under MR Credit 3. Similar to steel construction, precast/prestressed concrete construction allows for the possibility of existing section removal during demolition of one project and reuse in a new project. This is achieved in similar manner to that of steel construction as members can require little modification before reuse. However, a similar issue as that which occurs in cast-in-place concrete construction can hinder this because care must be taken to ensure that an existing section possesses adequate strength properties through testing. Also, analysis must be conducted on the existing component for its applicability within a new structural design. These issues also rely heavily on the initial use of the prestressed/precast member. For example, a project must initially allow for removal of a component from the structural system with impact or demolition that could affect that member (a factor for systems that employ spandrel beams with a poured concrete deck) in its reuse. Similarly, for projects that do allow for the above, the existing member must be of both usable geometry and strength for the new project. While these hurdles may be 52

71 difficult for a project to overcome, it is possible for prestressed/precast concrete construction to achieve the goal intended by MR Credit 3: Section Reuse in the LEED 2009 rating system. Also, similar to the discussion on cast-in-place concrete sections, prestressed/precast concrete construction allows for the use of recycled materials in concrete mix design. The materials involved in prestressed/precast concrete construction can also be employed as recycled materials after demolition. Prestressed/precast concrete construction also offers the additional ability to employ higher recycled materials contents as both concrete design mixtures and the curing process can be controlled in way not possible in cast-in-place concrete construction. This allows designers to achieve strengths and material properties not possible in cast-in-place construction while still meeting and intentions of MR Credit 4: Materials Reuse with the possibility of even higher recycled materials contents Prestressed/Precast Concrete Member Production The production energies and raw material required for prestressed/precast concrete are very similar to cast-in-place concrete with the addition of a key element. While production of cement and concrete for both cast-in-place and prestressed/precast construction is similar, additional energy can be required for prestressed/precast members that require specific curing methods. To increase the curing speed and strength gain time for prestressed/precast concrete section, producers can employ steam curing and other methods. The addition of these methods increases the energy required during production and can affect the total required production energy and materials. For accurate sustainability calculations, the issues discussed above affecting the material production of cement and concrete are needed to be included with the additional curing energies. The increased control over section production involved in prestressed/precast construction can provide a project with the ability to increase section durability and stiffness. As a result, prestressed/precast concrete construction attempts to include measures that can decrease the maintenance costs associated with project operation. However, both of these measures can affect sustainability in negative ways. While maintenance costs are attempted to be driven down, practice has displayed 53

72 that project maintenance costs associated with operation can often be higher for prestressed/precast construction (Naik 2008). Along with this, the addition of durability and strength increase materials and admixtures can adversely affect section brittleness, which can account for the additional maintenance costs mentioned previously. However, prestressed/precast concrete construction offers the opportunity for reinforcement placement and control. Similarly, prestressed/precast concrete construction has, in general, much better quality control that traditional reinforced concrete. All of these issues affect project sustainability and production sustainability by the increase energy and materials costs associated with section production as well as maintenance. The increased energy involved in improving concrete strength properties can thus adversely affect whole project sustainability. Again, as with cast-in-place concrete, the measures required for determination of production energy requirements can be difficult to fully quantify and have significant effects on production design alternative selection Recycled Materials Content and Prestressed/Precast Concrete Similar to cast-in-place concrete and steel construction, prestressed/precast concrete construction allows for the use of recycled materials in its design. These recycled materials often include fly-ash, silica fume, slag or recycled aggregate as with cast-in-place concrete mix design. However, due to the control possible in production of prestressed/precast members, percentages for recycled materials contents can be increased due to different potentially better curing methods than cast-in-place concrete members. The recycled materials content included in members vary relative to application in a project. Prestressed/precast concrete sections can also offer an end-oflife recycling option, just as cast-in-place construction, of the reuse of demolished sections as aggregate or fill Other Sustainable Qualities of Prestressed/Precast Concrete As with steel construction, prestressed/precast construction provides a project with the ability for members to be loaded immediately upon placement. This advantage can allow for streamlined construction schedules similar to those possible with steel construction. Additionally, prestressed/precast construction allows for more complex designs that involve structural system members playing several roles in a project s 54

73 systems. For example, available to prestressed/precast construction can be the option for piping, HVAC or other systems to be included in section design. This inclusion allows for these additional systems (electrical, plumbing, HVAC, etc.) to be put into place while structural construction is proceeding. This means that a project can complete multiple systems during the same time and drive construction time and costs down. In essence, prestressed/precast concrete sections do not limit additional systems designs as strictly as steel construction can, and does not require on-site curing time as with cast-in-place concrete. All of these reasons can add to a project s overall sustainability. Similar to transportation of structural steel members and materials for cast-inplace concrete construction, transportation of elements to project sites can create limitations. Whereas a project and designer may call for a larger component/member, site access limitations can reduce the overall project sustainability by requiring that member to be a single element. This can mean that while the opportunity to be sustainable is provided in prestressed/precast construction, limitations can also exist. 6.5 Conclusions Below are the conclusions that have been drawn from this study relative to each of the material types discussed. Table 6.1 provides a summary of these conclusions Sustainable Qualities and Issues for Steel Many issues surround the use of steel as a construction material and its relationship to sustainability. However, it can be seen that steel construction offers the positive attributes to project sustainability of individual or frame section reuse, recycled materials content possibility, durability, opportunity for streamlined construction schedules and a short period between placement and ability to resist load. The negative sustainable attributes associated with structural steel of byproduct emission from production (most specifically carbon dioxide), operational and maintenance requirements including fire and corrosion protection, required testing for section or system reuse and significant (and not fully defined) production energy requirements Sustainable Qualities and Issues for Cast-in-Place Concrete As illustrated, numerous issues surround the use of cast-in-place concrete as a construction material and its relationship to sustainability. However, it can be seen that 55

74 cast-in-place construction offers the positive attributes to project sustainability of abundant raw materials, possibility of recycled materials contents, ability to be recycled for future construction and unique construction and scheduling opportunities relative to the other materials discussed herein. The negative sustainable attributes associated with cast-in-place concrete of byproduct emissions including several GHGs, significant energy requirements for cement production, additional energy requirements for concrete production, higher energy requirements for incorporation of pozzolanic or recycled materials, materials placement limitations and wastes generated during construction Sustainable Qualities and Issues for Prestressed/Precast Concrete Prestressed/precast concrete has many issues surrounding its use as a construction material and its relationship to sustainability. However, it can be seen that prestressed/precast construction offers the positive attributes to project sustainability of abundant raw materials, possibility of recycled materials contents, ability to be recycled for future construction, possibility for streamlined and multi-system construction, short period between placement and service and the possibly for more durable and complex design configurations. Combating these are the negative attributes of byproduct emissions including several GHGs, significant energy requirements for cement production, additional energy requirements for concrete production, higher energy requirements for incorporation of pozzolanic or recycled materials, limitations imposed by site access and relatively high maintenance costs. 56

75 Material Benefits Shortcomings Ability for frame and section reuse CO 2 emissions Recycled materials content Operational and maintenance possibility requirements Durability Possibility for streamlined Required testing for construction schedules requalification Short period from placement to Significant energy requirements service for production Abundant raw materials Byproduct emissions (Various Structural Steel C.I.P. Reinforced Concrete Prestressed Precast Concrete Ability for use as a recycled material Recycled materials content possibility Unique construction/scheduling properties Abundant raw materials Possibility of recycled materials content Ability to be employed as a recycled material Possibility for streamlined/multisystem construction Short period from placement to service Possibility for high durability and complex designs GHGS) Significant energy requirements for raw material (cement) production and recycled materials contents Construction constraints/material placement limitations Construction Wastes Byproduct emissions (Various GHGS) Significant energy requirements for raw material (cement) production and recycled materials contents Construction constraints/material placement limitations Relatively high maintenance costs. Table 6.1. Structurally applicable sustainable properties of steel, cast-in-place concrete and prestressed/precast concrete as construction materials 57

76 Chapter 7: Review of Life Cycle Analysis Computer Programs 7.1 Introduction Successful sustainable design of any structure relies on the ability of designers to provide input to a client on design alternatives. Accurate design alternative prediction requires various measures of energy and environmental impact analysis involving a range of issues. The issues include but are not limited to the production energies associated with construction materials as well as an analysis of the environmental impact materials can have over their lifetime. While the producers of façade and non-structural building construction materials present designers and engineers with the sustainable properties of their products, all construction materials involved must be accounted for. This means that a project must account for the sustainable impact that all materials included in construction have during all planning and construction phases. Accurate prediction of energy and environmental measures are what contribute to the total life-cycle analysis (LCA) of a project. The sustainability of individual materials contributes to total project sustainability and accurate prediction of sustainable qualities are required during design alternative analysis. To achieve more accurate predictions and allow for direct side-by-side comparison of designs sustainable properties, the energy requirements for production/use, environmental impact, and end-of-life options must be better determined. The construction materials industries and research institutions actively must actively pursue these material sustainable properties in an effort to achieve increased accuracy. Private companies and government entities have created tools, in the form of lifecycle analysis computer programs, to assist designers in these predictions. These lifecycle analysis programs vary in capability and address different issues, such as focusing solely on energy use, environmental impact or other LEED rating point applicable sustainable properties (e.g., air quality, use of natural light, waste management, etc.), 58

77 associated with project planning and construction. These programs make calculations based on data from a variety of industries and attempt to unify the results between alternative designs. In this study, three programs (Building for Environmental and Economic Sustainability (BEES) v4.0, SimaPRO v7.1 and Athena Impact Estimator v4.0) have been evaluated for their applicability to the life-cycle analysis of buildings alternatives. These programs employ databases created from information provided by various sectors of the construction materials production and construction industries and rely on the reported energy values, environmental impacts, and other sustainable properties of construction materials and construction processes. Both positive and negative aspects relating to measurement of sustainable qualities of design alternative of these programs use will be presented. Also, figures displaying program input requirements and output values where relevant. 7.2 Building for Environmental and Economic Sustainability (BEES) v4.0 The Building for Environmental and Economic Sustainability (BEES) computer program is a life-cycle analysis tool that performs side-by-side comparison of a single construction material type involved in project design at a time. The program interface allows its user to set weighting ratios for various aspects of both environmental and economic impact resulting from a product s use and compare it to another product in the same major group element. Figures 7.1 and 7.2 show the initial program screen and the option for applying rating ratios: 59

78 Figure 7.1. Screenshot of initial program screen for BEES v4.0 Figure 7.2. Screenshot of ratio weighting option offered by BEES v4.0 60

79 An example of the program s materials comparison options would include comparison of two concrete beams, made with 100% Portland cement mix and 15% flyash cement mix concrete respectively, from either the same or different locations (input as distance from manufacturing plant to project site). As described earlier, construction discount rates for each of these beams can be weighted for user economic and environmental importance and compared against their performance in both categories. The ratios calculated for the environmental impact and economic performance of a product over its life cycle are generated from a database contained within the program of applicable product properties and uses. The values in these databases are provided by the program for user review and contain the associated raw material inputs, byproducts of production, wastes due to installation and maintenance, type of energy employed in production and land use associated with life-cycle stage of a construction material. The program s creators, the United States National Institute of Standards and Technology, periodically update the values in these tables BEES v4.0 employs these databases to provide the user with both tabular and graphic representations of the products being compared BEES v4.0 Program Outputs Outputs from the BEES v4.0 program provide users with comparisons of single construction material type on both economic and environmental scales. The program inputs require users to provide distance to project site from supplier, indicating that the tables employed in generating these outputs consider transportation costs and environmental impacts. Using the weighting option provided, a user can indicate which byproduct emissions or energy use issues are most important for comparison as well as designate the importance of economic or environmental data to a project s design. Each of these inputs are applied the material selections made by a user from the provided program database. The program then assesses each of the materials selected and provides the user with both graphical and tabular outputs as well as an overall performance combining economic and environmental outputs relative to user weighting. Provided below are examples of program graphical output of both economic, environmental and overall performance for an unweighted material comparison of the three façade materials 61

80 stucco, aluminum siding and trespa meteon with the same distance to project site values. The economic performance output provides the user with both the first and future costs as well as the sum. As displayed in Figure 7.3, the future cost values can be both positive and negative and are related to a materials ability to provide a project with a financially advantageous use. The vertical axis of Figure 7.3 is the present value costs associated with the previously discussed example while the horizontal axis is the three design alternatives. It should also be noted that values provided from these outputs are at present value costs. Figure 7.3. Economic performance graphical output for stucco, aluminum siding and trespa meteon comparison The environmental performance output, Figure 7.4, provides the user with measures of several environmental factors including the following; acidification, critical air pollutants, ecological toxicity, eutrophication, fossil fuel depletion, global warming, habitat alteration, human health, indoor air quality, ozone depletion, smog and water 62

81 intake. The measures in this output are gathered from industry data that are provided to the program in the aforementioned performance tables. Figure 7.4. Environmental performance graphical output for stucco, aluminum siding and trespa meteon comparison The program assess the tabular data as well as the user input weights and distance from producer data. These values are converted within the program to percentages of performance that are then converted to a points system. Each of the above mentioned categories contribute to this point system and the program provides the user with and overall (with user defined weights where applicable) environmental score for the materials being compared. The vertical axis of Figure 7.4 is the scores associated with the previously discussed example while the horizontal axis is the three design alternatives. As illustrated by Figures 7.3 and 7.4 from the provided example, stucco has a relatively low economic cost with a high environmental performance (lower scores in environmental performance as desired). The BEES v4.0 computer program also provides the user with and overall performance output, displayed in Figure

82 Figure 7.5. Overall Performance Graphical Output for Stucco, Aluminum Siding and Trespa Meteon comparison This output combines the economic and environmental performance outputs considering any weighting ratios that are defined by the user. In the above example, the program default weighting ratios (a 50%/50% consideration for both economic and environmental performance) were employed. As displayed in the vertical axis of Figure 7.5, the score values associated with both economic and environmental performance are combined and presented in a similar manner to Figures 7.3 and The program notes that lower values are desired in the overall performance measurement. Figure 7.5 displays that, in the example provided above, aluminum siding is the project s best overall choice, unlike what was identified in the economic or environmental performance graphs separately (i.e. Figure 7.3 and 7.4) BEES v4.0 Sustainable Measurement Advantages The BEES v4.0 computer program offers users the ability to compare construction materials of the same category side-by-side. side. As illustrated in the example above, the 64

83 BEES v4.0 program provides users with insight into a specific building material choice and its relevance to their project s design. The program also allows users to weight the importance of these outputs to their overall project goals. These options can have positive impacts on total project sustainability by allowing its users to consider the economic and environmental impact of material choice. By comparing different façade material options (as done in the provided example), a project can determine the effect that a product with a lower environmental impact located further from the project site can have over other alternatives. This insight allows a project to determine which material can best serve their sustainability goals most effectively. The program output provides its users with both tabular and graphical representations of material comparisons. The combination of the environmental and economic performances of a material for the overall performance provides a project with the ability to consider multiple weighted alternatives. The BEES v4.0 program also allows for several iterations to be run on the same material type allowing for consideration of several product suppliers of the same material (although each investigation requires that a new model be constructed for the same material from different locations). Similarly, a user can run several iterations considering building materials in different categories for comparison. While these comparisons across categories cannot be on the same model, the BEES v4.0 program can provide output on each individually for visual evaluation. Again, this provides more insight into material sustainability allowing for a project to better assess design alternatives BEES v4.0 Sustainable Measurement Disadvantages The BEES v4.0 computer program outputs are computed from internal tables. These tables are generated from industry data as well as other research. While updates to these tables are made periodically, the BEES v4.0 program does not allow user to change table values. Also, the data from which these values are obtained are also not provided to users. Due to this, the results offered from the program analysis may not serve a particular project, as the values provided from the program may not meet actual values of a producer or material being considered. Therefore, the program may provide its user with an incorrect solution for their design alternative considerations. 65

84 Along with this, the program can only provide a user with comparisons of one building material type at a time. While multiple alternatives within the building type can be compared, alternative interactions cannot without running several models. For example, a user might want to compare façade alternatives considering multiple window alternatives. Each analysis would need to be run separately and cannot be combined. This means that output would only provide a project insight about one material on its own and not data on consideration of alternative materials that may be possible from multiple suppliers. This can be a major hindrance to total project sustainability as building materials may be selected that do not produce the most sustainable design. Included in these limitations is the lack of ability to define material quantities within the program. While comparisons are made between material types, the BEES v4.0 program cannot consider the effect that larger or smaller quantities of one material relative to another in a design alternative can have. It can thus be concluded that the BEES v4.0 program cannot consider if economy of scale or construction advantages were available between different design alternatives. These negatives can outweigh the positive program aspects if accurate, and indepth comparison is required for a project. It can also limit the ability of project designers to effectively contribute to project sustainability and effect a project s overall sustainable qualities. 7.3 SimaPRO v7.1 The SimaPRO v7.1 computer program is a life cycle analysis tool employed in the general calculation of a product s environmental and economic impact. SimaPRO v7.1 bases its calculations off of databases that include inputs from various sectors of the production industry including, but not limited to, raw materials and energy requirements for production. The program offers its user the ability to create and change the values in its databases to better suit a designer s needs. The SimaPRO v7.1 computer program also allows the user to select datum input for a life cycle and environmental impact analysis for a user-defined product generated from a program-defined list of raw materials. However, detailed investigation into all aspects of production must be conducted prior to the combination of raw materials for a new, non-program defined product. Figure 7.6 is 66

85 an example of a program-defined product, 1.0 kilogram of cattle feed, and the raw materials product tree provided by the SimaPRO v7.1 program. Figure 7.6. SimaPRO v7.1 product tree for 1.0 kilogram of cattle feed With both the database and user-defined products, the program can produce side- by-side comparison of the raw material inputs involved in alternative product designs. SimaPRO v7.1 also offers its users the ability to select various types of analysis methods from different regions of the world. Most notable to this study, the program allows for the use of the BEES analysis method (Section 7.2) and the Tool for the Reduction and Assessment of Chemical and other environmental Impacts (TRACI) produced by the United States Environmental Protection Agency. Using these analysis tools, the program is able to generate both tables and figures that display the distribution of energy, environmental impact and life-cycle cost associated with a product s production following the guidelines explained by the applicable ASTM standards for life cycle analysis calculation (ASTM E917-05, ASTM E ) SimaPRO v7.1 Program Outputs 67

86 SimaPRO v7.1 provides users with both tabular and graphical outputs of total environmental outputs for a product. Several raw material input measures are considered in the program analysis. These input measures are combined to determine the contribution that each can have on several program defined environmental factors including, but not limited to; global warming, acidification, human health-cancer, human health-non-cancer, human health criteria-air air pollutants, eutrophication, smog, natural resource depletion and ozone depletion. The applicable raw material impact measures for a product are considered and employed by the program to illustrate the effect that each has on the environment. Figure 7.7 illustrates a graphical output from the SimaPRO v7.1 program for the example of 1.0 kilogram of cattle feed mentioned in Section 7.3. Figure 7.7. SimaPRO v7.1 Graphical Output for One (1) Kilogram of Cattle Feed SimaPRO v7.1 Sustainable Measurement Advantages Many of the features included in the SimaPRO v7.1 program package can be advantageous to a user in considering design alternatives. The program provides users 68

87 with numerous defined products that have been compiled and are based off of industry data. This can allow a user and project to assess the sustainability of a product without product production investigation. Along with this, the SimaPRO v7.1 program allows its users to define their own products from the provided list of input raw materials. Thus, a project can tailor a product to its specific use and consider its sustainability from that. Similarly, the program also allows a user to access and change database values. This may require more detailed investigation into a product, but can allow a project to determine the sustainability of an option in a more effective manner. The SimaPRO v7.1 output provides its user with side-by-side comparison of products based on environmental measures considering their raw materials. This allows design professionals to assess the sustainability of several design alternatives while considering each alternative s raw material inputs effect and availability. The program also allows for this to be done under multiple comparison measures (the BEES comparison and TRACI) allowing for a product analysis on two scales providing designers with more data. The program can provide its user with multiple outputs for various important project aspects. Most specifically the environmental, energy and economic values associated with products. This is all done through a program-defined life cycle cost analysis SimaPRO v7.1 Sustainable Measurement Disadvantages The immediate and effective use of the SimaPRO v7.1 program is to provide a user with a life cycle cost (LCC) or life cycle analysis (LCA) for product alternatives. While this can serve comparison of products, the SimaPRO v7.1 program is not tailored for comparison of building or structural materials. The SimaPRO v7.1 program aims to compare products, not designs. Its ability for editing and creation of user-defined products can achieve the goals of a design alternative analysis, but detailed investigations are required for these product definitions as well as for accurate design alternative comparison. Due to this, significant time and energy may be required for this program s output to be of value to a project assessing its overall sustainability. Contributing to lack of value in program output are the limitations imposed by the 69

88 program-defined raw materials. Any user-defined products must be possible from configurations of program-defined materials and thus can limit the types of products that can be defined. As the program does not allow for definition of any product, it can greatly limit the effectiveness that its outputs can have on design alternative comparison. This relates directly to the limitations imposed by the program from its database. As with the BEES v4.0 program, SimaPRO v7.1 can only produce results relative to its database. If there exist errors in the manner in which data was collected or a product being considered is produced/consists of materials outside the program-defined database, the outputs may not be relevant to a project s intended comparisons. Similar to the BEES v4.0 program, SimaPRO v7.1 also cannot consider quantities in its calculations. As discussed in Section 7.2.3, this means that alternative designs could not accurately reflect advantages that one product can provide over another used in a project. Each of these limitations contribute to the overall effectiveness of the SimaPRO v7.1 computer program in comparing alternative design options for a project and affect the effectiveness that program outputs can have for project material choice. 7.4 Athena Impact Estimator v4.0 The Athena Impact Estimator v4.0 computer program is a building system environmental effect calculation tool designed to help engineers and designers determine the summary measures and/or absolute environmental effect of a design alternative by either life-cycle stage or assembly group embodied effects. The program allows users to create alternative building systems, based on both provided product details user-defined products, that are compared against total (as well as by life-cycle stage) environmental impact. The databases included in the program are generated from industry values considering various energy use aspects including, but not limited to; electricity, hydropower, coal, diesel, feedstock, gasoline, heavy fuel oil, natural gas and nuclear. A designer would generate a model based on a simple building layout (e.g., number of bays, length of bays, etc.) for each applicable level of the building. Interior and façade details can also be specified. The program employs the user-input design data to generate total quantities of raw materials, which are displayed by a Bill of Materials report (an 70

89 example is provided in Figure 7.8). Figure 7.8. Athena impact estimator v4.0 bill of materials report generic example The Athena Impact Estimator v4.0 then applies program-defined constants to display, in either table or graph form, the total environmental impact relative to a design over the building product s life cycle stages. These stages are program-defined and consist of manufacturing, construction, maintenance, end-of-life and operating energy. Along with these individual stages, the program provides an overall energy use assessment for each energy type combining the values of each life cycle stage. The Athena Impact Estimator produces these tables and graphs for each project but allows for multiple projects to be analyzed side-by-side on separate graphs Athena Impact Estimator v4.0 Program Outputs The Athena Impact Estimator v4.0 provides the user with both tabular and graphical representations resentations of energy use involved in a building design alternative for the entire project life cycle. The program allows for the selection of various project locations within North America, that alter the database employed by the program in calculating 71

90 project energy values. This is due to varying energy use by region North America and is encapsulated in the program-defined databases. The program interface and input requirements are most effectively employed for projects considering building design alternatives not project design alternatives. Provided in Figures 7.9 and 7.10 are equivalent tabular and graphical representations of output data from a generic building design alternative and illustrate the type of outputs (ex. electricity, coal, natural gas, etc.) associated with a building. Figure 7.9. Athena Impact Estimator v 4.0 tabular output-generic example 72

91 Figure Athena Impact Estimator v 4.0 graphical output-generic example The energies presented in the program outputs are determined from a database. As a user provides project details, the Athena Impact Estimator v4.0 calculates a bill of materials report for each input. The program then totals the materials included in the project s building design model and determines energy use along project life cycles from database entries. Both the tabular and graphical representations include the various units of measure associated with each energy type. The two areas under which energy use are calculated for each life cycle stage are materials and transportation. These values are directly related to the user-defined material choices and geometry and the program- defined databases. Multiple outputs can be generated for design alternatives and displayed on separate tables and graphs at the same time. However, these tables and graphs cannot be displayed on one graph or table at the same time. Values from tables can be exported to Microsoft Excel for further analysis Athena Impact Estimator v4.0 Sustainable Measurement Advantages The Athena Impact Estimator v4.0 offers many advantages for sustainable project 73

92 design. One of the most predominant advantages offered by the program is the ability to consider multiple design alternatives. This allows a project to present energy and environmental impact analysis for various layouts or designs and compare them simultaneously. The designers then can compare design alternatives and make more informed decisions. Similar to this, the program can provide users with analysis results from multiple viewpoints such as by life cycle stage or embodied energy. This means that designers can consider the impact of their material choices relative to project life cycles as well to total project energy requirements. Designers can thus make conclusions based on this data relative to aspects (construction issues, maintenance issues, etc.) important to their project. This also means that alternative design choices can display what areas of the project life cycle will require greater energy expenditures and allow a project to plan for this in their final design decisions. The databases included in the program are from industry data and other outside research efforts. It can be assumed that this data was gathered from various regions within North America and thus can provide a user with accurate input relevant to their project site. These database and regional considerations can be important to project design alternative choices as their accuracy can influence the decision of designers. The Athena Estimator v4.0 has the ability to include material quantities in its calculations. Inclusion of these quantities increases the accuracy with which design alternatives can be compared. This accuracy can aid users and project designers to determine what design alternatives meet, exceed or fall short of their sustainability goals. Another positive sustainable quality of the Athena Impact Estimator v4.0 is that its databases and user interface consist of both interior and exterior structural elements. This does not mean that the program can analyze a structure for its effectiveness to resist loads. Rather, it means that the program can consider elements of a projects design rather than simple architectural or structural aspects separately. The program can also assess a building design alternative over its life. This allows designers to consider aspects surrounding material/design choice including end-of-life options Athena Impact Estimator v4.0 Sustainable Measurement Disadvantages 74

93 One of the key issues in program use and output, as with the previously discussed programs, are the reliability of the program defined databases. While the program employs industry and research data, the applicability of this data to a specific project may be incorrect. It is difficult to verify the data because it is not clear to the user every input comes from. This means that a user may assess design alternatives that display energy values that are not accurate relative to their material choices and product availability within the project site s region. This can limit the ability of both the program and designers to accurately predict the energy expenditures associated with alternative project designs. The Athena Impact Estimator program shows that energy requirements increase as material quantity increase. However, the program does not provide the user with individual section or member sizes, just an increase in energy relative to span length. Parametric studies employing the Athena Impact Estimator v4.0 are provided in Chapter 8. These studies display program use and output more accurately, and depict that the increases in energy are general comparison of design alternative. The final negative sustainable quality associated with the Athena Impact Estimator v4.0 is that its use for design alternatives can require extensive input and data. Geometry, layout and initial design are required to achieve an accurate design alternative comparison from the program. This means that both design time and energy must be employed to first determine the various design alternatives as well as enter their required data for program analysis. While this may not be difficult on relatively small projects, as size and complexity increase, design time will increase. This can harm overall project sustainability, as program results may not be accurate. This can lead to modeling that detracts from design alternative decisions choices rather than adds to their effectiveness. 7.5 Conclusions and Program Highlights Review and analysis of the three computer programs presented (Building for Environmental and Economic Sustainability (BEES) v4.0, SimaPRO v7.1 and Athena Impact Estimator v4.0) led to the following program specific and general conclusions BEES v4.0 Program Conclusions The BEES v4.0 program allows for the side-by-side comparison of building 75

94 materials and can integrate location from supplier to site. Simultaneous economic and environmental analyses can be conducted including weighting ratios relative to their importance within a project decisions making process. The program also relies heavily on a product materials database. One shortcoming of the BEES v4.0 program is that it compares only materials and not project design alternatives directly. As a result only general product conclusions can be drawn. In addition, there is uncertainty about the products database and what information is employed to generate it. Thus, program outputs may not accurately reflect desired project design alternatives. Finally, the program does not allow for material quantity comparison SimaPRO v7.1 Program Conclusions The SimaPRO v7.1 program offers a user an extensive database of predefined materials as well as the ability to edit these materials to generate new product as required for design alternatives. It also provides a user with side-by-side product comparison as well as visual raw material inputs to the project under analysis. The program also allows the user to perform environmental, energy and life cycle analyses using various analysis methods including the BEES and TRACI methods. SimaPRO v7.1 falls short as it only allows for comparison of product alternatives and not design alternatives. As a result, limited raw material inputs can hinder the ability of a user to clearly define new products leading to limitations in the results and their effectiveness in project design alternative decision-making. Similar to the BEES v4.0 program, the program database can limit comparison effectiveness as well as its inability to consider material quantities Athena Impact Estimator v4.0 Program Conclusions The Athena Impact Estimator v4.0 program includes environmental and energy analysis measures. The program also allows for alternative design comparison by life cycle stage or embodied energy effect. The values for which are determined from an industry-generated database that includes both interior and exterior building components. It can provide insight into energy expenditures and environmental impact at each step along building life. Unlike the other programs discussed, the Athena Impact Estimator 76

95 considers material quantities in its analyses. The Athena Impact Estimator v4.0 falls short on its effectiveness as a sustainable design alternative comparison tool because of the trends it applies to its output data. Energy requirements are shown to increase relative to material quantity increase and measurements do not indicate changes in section size (this is depicted in more depth in the studies contained in Chapter 8). Also, the program has difficulty in accurately comparing varying structural design layouts and focuses on general architectural and quantity comparisons. Similar to the previous programs discussed, it also relies heavily on an industry-defined database that may not always be accurate General Life Cycle Analysis Computer Program Conclusions In general, the three life cycle analysis programs reviewed rely heavily on databases for analysis. These databases can distort outputs in a manner not helpful to design alternative decision-making. The reviewed programs also lack the ability to fully define a project s building envelope and/or structural system. This limits how a project can compare design alternatives. Care must also be taken in program use to address aspects of project sustainability in effective and meaningful ways. Each of the programs reviewed only provide general comparisons for design alternatives. This limits the accuracy with which conclusions about design alternative can be made. Also, none of the programs reviewed relate material strength, durability and other properties with their program-defined sustainable properties. This limits the type of comparisons that can be made as well as the effectiveness of any research based on these programs use. The programs reviewed are not effective for structural system or whole project modeling on their own. Use of multiple programs may lead to more effective design results, but this is unclear as their shortcomings are often overlapping and may not provide all the necessary solutions for accurate design alternative comparisons at this point in time. 77

96 Chapter 8: Modeling and Analysis with the Athena Impact Estimator v Introduction This chapter presents sustainability analysis of beams, columns and concrete slabs using the Athena Impact Software v4.0. It was concluded from the review of available computer programs that the Athena Impact Estimator v4.0 would best serve in parametric studies to assess the relationship between structural members and energy consumption. This modeling was conducted to evaluate the energy consumption values associated with the following structural elements and properties: Wide Flange (WF), Concrete and Glulam columns energy consumption relative to column height Wide Flange, Concrete and Glulam columns energy consumption relative to live load Wide Flange, Concrete and Glulam beams energy consumption relative to span length Wide Flange, Concrete and Glulam beams energy consumption relative to live load Concrete Suspended Slabs energy consumption relative to span length Concrete Suspended Slabs energy consumption relative to live load Concrete Suspended Slabs energy consumption relative to concrete strength The concrete strength of Concrete Suspended Slabs energy consumption relative to live load The fly-ash percentage of Concrete Suspend Slabs energy consumption relative to gross floor area The fly-ash percentage of Concrete Suspend Slabs energy consumption relative to live load This modeling assesses the output energy values associated with varying widths and lengths of the columns, beams and slabs displayed in Figure

97 Figure 8.1. Illustration of structure employed as generic model for Athena Impact Estimator v4.0 energy consumption assessment For each of the studies, the values for height, span, live load, concrete strength and concrete fly-ash percentage were varied individually holding other values constant to determine the effect that each had on energy consumption as predicted by the Athena Impact Estimator v4.0. The manner in which each value was varied is presented in the next section 8.2 Modeling Parameters Figure 8.2 displays the initial input screen when starting a new project in the Athena Impact Estimator v4.0 computer program. 79

98 Figure Screenshot of initial input interface for a New project in Athena Impact Estimator v4.0 In all modeling, the Location dropdown window was set to USA. Also, the Building Type was maintained as Commercial. Displayed on Figure 8.2 are two highlighted inputs. These inputs are Gross Floor Area and Building Life Expectancy. All studies were conducted in Imperial units. The Number and Description input fields were left blank. Figure 8.3 displays the input screen obtained after completing the initial input screen parameter inputs and clicking the Edit dropdown tab in the program interface and selecting Add Assembly, Floor and Concrete Suspended Slab. 80

99 Figure Screenshot of interface for Concrete Suspended Slab in Athena Impact Estimator v4.0 Displayed on Figure 8.3 are five highlighted inputs: Floor Width, Span, Concrete Flyash %, Concrete and Live Load. Figure 8.4 displays the input screen obtained by clicking on the Edit dropdown tab in the program interface and selecting Add Assembly and Mixed Columns and Beams. 81

100 Figure 8.4. Screenshot of interface for Mixed Columns and Beam in Athena Impact Estimator v4.0 In all modeling, the Number of Columns and Number of Beams were set to 4. Displayed on the figure are six highlighted inputs: Bay Size, Supported Span, Floor to Floor Height, Live Load, Column Type and Beam Type. Table 8.1 provides a list of all highlighted inputs for reference. Highlighted Input Label Input 1 Input 2 Input 3 Input 4 Input 5 Input 6 Input 7 Input 8 Input 9 Input 10 Input 11 Input 12 Input 13 Reference to Figure Name Reference Figure 14 Gross Floor Area Figure 14 Building Life Expectancy Figure 15 Floor Width Figure 15 Figure 15 Span Concrete Flyash % Figure 15 Concrete Figure 15 Live Load Figure 16 Bay Size Figure 16 Supported Span Figure 16 Floor to Floor Height Figure 16 Live Load Figure 16 Column Type Figure 16 Beam Type Table 8.1. List of highlighted input labels and references 82

101 For each study, individual models were built. After model construction, the project heading, displayed in Figure 8.5, was highlighted. Figure 8.5. Screenshot of project assembly tree with project heading highlighted With the project heading highlighted, the Reports tab was selected. Figure 8.6 displays the interface window associated with the Reports tab and highlights the four areas of importance. 83

102 Figure 8.6. Screenshot of Reports interface window with highlighted areas Figure 8.6 displays the Report Format as Table, the Format as Absolute Value, the Type as By Life Cycle Stages and that the Absolute Values box for Energy is checked. These same selections were made for all models. Once these e selections were made, the Show Reports button was pressed. Pressing this button produced the Athena Impact Estimator v4.0 output table of Energy Consumption Absolute Value By Life Cycle Stages for each model. This table includes the life cycle stages; Manufacturing, Construction, Maintenance, End Of Life, Operating Energy and Total. The measured energies provided in these tables include; Electricity (kwh), Hydro (MJ), Coal (MJ), Diesel (MJ), Feedstock (MJ), Gasoline (MJ), Heavy Fuel Oil (MJ), LPG (MJ), Natural Gas (MJ), Nuclear (MJ) and Wood (MJ). It should be noted that not all measured energy outputs, as listed in the previous sentence, are included in all model output tables. The measured values are dependent on the materials being assessed. However, measured energy outputs are generally included in all the models employed in this study with the exception of Wood 84

103 (MJ), which varies with the selection of Glulam for Inputs 12 and 13. The values from these tables were exported from the Athena Impact Estimator v4.0 to Microsoft Excel. From there, all units were converted to MJ (the conversion unit of 1 kwh = 3.6 MJ was employed in converting the Electricity output) and summed for a total energy consumption value for each model. These total energy consumption values were then compared via the parameters varied in each study. All exported tables are provided in Appendix A. 8.3 Athena Impact Estimator v4.0 Parametric Studies This section provides the information relevant to the parametric studies that were conducted Study 1: Column Energy Consumption The intention of this study was to assess the required energy consumption per length of three column types (Wide Flange, Concrete and Glulam) as predicted by the Athena Impact Estimator v4.0 computer program. In this study, all values associated with the slab and beams lengths and widths (as illustrated in Figure 8.1) were held constant while the floor-to-floor height, column type and live load were varied Study 1: Input Values Table 8.2 displays all input labels included in this study along with their constant or varied value, a reference to their name and a reference to their applicable figure. Table 8.2 also displays the values for the parameters that were varied as applicable. 85

104 Input Reference to Name Reference Value Unit Label Figure Input 1 Figure 14 Gross Floor Area 400 ft 2 Input 2 Figure 14 Building Life Expectancy 50 Years Input 3 Figure 15 Floor Width 20 ft Input 4 Figure 15 Span 20 ft Input 5 Figure 15 Concrete Flyash % average % Input 6 Figure 15 Concrete 4000 psi Input 7 Figure 15 Live Load 45 psf Input 8 Figure 16 Bay Size 20 ft Input 9 Figure 16 Supported Span 20 ft Input 10 Figure 16 Floor to Floor Height Varied (10-15) ft Input 11 Figure 16 Live Load Varied (45, 75, 100) psf Input 12 Figure 16 Column Type Varied (WF, Concrete, Glulam) -- Input 13 Figure 16 Beam Type WF -- Table 8.2. Values employed for inputs in study Study 1: Analysis The values provided in Table 8.2 were employed to generate models for each of the varied parameters. The Energy Consumption Absolute Value By Life Cycle Stages output tables for each model from the Athena Impact Estimator were generated and are provided in Appendix A1. Table 8.3 provides the total energy consumption values as tabulated from the values provided in Appendix A1 for each varied Column Type and Live Load by the applicable Floor to Floor Height. Table 8.3 was employed to generate Figures 8.7 through

105 Live 45 psf Live 75 psf Live 100 psf Column Type Column Height (ft) WF Energy (MJ) Column Type Column Height (ft) WF Energy (MJ) Column Type Column Height (ft) WF Energy (MJ) Column Type Column Height (ft) Concrete Energy (MJ) Column Type Column Height (ft) Concrete Energy (MJ) Column Type Column Height (ft) Concrete Energy (MJ) Column Type Glulam Column Type Glulam Column Type Glulam Column Height (ft) Energy (MJ) Column Height (ft) Energy (MJ) Column Height (ft) Energy (MJ) Table 8.3. Total energy consumption values for study 1 as provided by the Athena Impact Estimator v4.0 for the applicable input variations 87

106 195.0 y = x R² = Energy Consumption (MJ x 10 3 ) y = x R² = 1 y = x R² = Column Height (ft.) WF Concrete Glulam Figure 8.7. Column height vs. total energy consumption at a live load of 45 psf y = x R² = Energy Consumption (MJ x 10 3 ) y = x R² = y = x R² = Column Height (ft.) WF Concrete Glulam Figure 8.8. Column height vs. total energy consumption at a live load of 75 psf 88

107 225.0 y = x R² = Energy Consumption (MJ x 10 3 ) y = x R² = y = x R² = Column Height (ft.) WF Concrete Glulam Figure 8.9. Column height vs. total energy consumption at a live load of 100 psf Energy Consumption (MJ x 10 3 ) Live Load (psf) WF Concrete Glulam Figure Live load vs. total energy consumption for columns 89

108 Figures 8.7 through 8.9 display the relationship between Column Height and Total Energy Consumption that the Athena Impact Estimator v4.0 output tables provide for the three column types investigated (WF, Concrete and Glulam) at the live loads investigated (45 psf, 75 psf, and 100 psf). Figure 8.10 displays the relationship between Live Load and Total Energy Consumption for the three column types investigated. Along with this, trendlines have been calculated in Microsoft Excel to determine the bestfit linear equation where applicable Study 1: Conclusions The following conclusions have been drawn from the graphs generated in this study: Energy consumption is highest with concrete as the column type devoid of column height Energy consumption increases linearly as volume of material of a column increases Steel columns are approximately 3-5 times more energy conservative than Concrete columns depending on live load Glulam columns are approximately times more energy conservative than Concrete columns depending on live load Glulam columns are approximately times more energy conservative than steel columns depending on live load Energy consumption increases as live load on columns increases Energy consumption is highest with Concrete as the column type devoid of live load choice 8.4 Study 2: Beam Energy Consumption The intention of this study was to assess the required energy consumption per length of a beam as predicted by the Athena Impact Estimator v4.0 computer program. In this study, the values associated with the columns height, slab length, beam length and slab width (as illustrated in Figure 8.1) were held constant, while the values for beam span, beam type and live load were varied Study 2: Input Values 90

109 Table 8 displays all input labels included in this study along with their constant or varied value, a reference to their name and a reference to their applicable figure. Table 8 also displays which parameters were varied as applicable. Input Reference Name Reference Value Unit Label to Figure Input 1 Figure 14 Gross Floor Area 400 ft 2 Input 2 Figure 14 Building Life Expectancy 50 Years Input 3 Figure 15 Floor Width 20 ft Input 4 Figure 15 Span 20 ft Input 5 Figure 15 Concrete Flyash % average % Input 6 Figure 15 Concrete 4000 psi Input 7 Figure 15 Live Load 45 psf Input 8 Figure 16 Bay Size Varied (15, 20, 25, 30) ft Input 9 Figure 16 Supported Span 20 ft Input 10 Figure 16 Floor to Floor Height 12 ft Input 11 Figure 16 Live Load Varied (45, 75, 100) psf Input 12 Figure 16 Column Type WF -- Input 13 Figure 16 Beam Type Varied (WF, Concrete, Glulam) -- Table 8.4. Values employed for inputs in study Study 2: Analysis The values provided in Table 8.4 were employed to generate models for each of the varied parameters. The Energy Consumption Absolute Value By Life Cycle Stages output tables for each model from the Athena Impact Estimator are provided in Appendix A2. Table 8.5 provides the total energy consumption values as tabulated from the values provided in Appendix A2 for each varied Beam Type and Live Load by the applicable Bay Size. This table was employed to generate the graphs in Figures 8.11 through

110 Live Load 45 psf Live Load 75 psf Live Load 100 psf Beam Beam Beam WF WF Type Type Type WF Beam Beam Beam Energy Energy Energy Length Length Length (MJ) (MJ) (MJ) (ft) (ft) (ft) Beam Beam Type Concrete Concrete Type Type Beam Concrete Beam Beam Beam Energy Energy Energy Length Length Length (MJ) (MJ) (MJ) (ft) (ft) (ft) Beam Beam Beam Glulam Glulam Type Type Type Glulam Beam Beam Beam Energy Energy Energy Length Length Length (MJ) (MJ) (MJ) (ft) (ft) (ft) Table 8.5. Total energy consumption values for study 2 as provided by the Athena Impact Estimator v4.0 for the applicable input variations 92

111 Energy Consumption (MJ x 10 3 ) Live Load (psf) WF Concrete Glulam Figure Beam length vs. total energy consumption at a live load of 45 psf Energy Consumption (MJ x 10 3 ) Beam Length (ft.) WF Concrete Glulam Figure Beam length vs. total energy consumption at a live load of 75 psf 93

112 Energy Consumption (MJ x 10 3 ) Beam Length (ft.) WF Concrete Glulam Figure Beam length vs. total energy consumption at a live load of 100 psf Energy Consumption (MJ x 10 3 ) Live Load (psf) WF Concrete Glulam Figure Live load vs. total energy consumption for beams 94

113 Figures 8.11 through 8.13 display the relationship between Beam Length and Total Energy Consumption that the Athena Impact Estimator v4.0 output tables provide for the three beam types investigated (WF, Concrete and Glulam) at the live loads investigated (45 psf, 75 psf, and 100 psf). Figure 8.14 displays the relationship between Live Load and Total Energy Consumption for the three beam types investigated Study 2: Conclusions The following conclusions have been drawn from the graphs generated in this study: Energy consumption is highest with Wide Flange as the beam type devoid of beam length Energy consumption increase as volume of material of a beam increases Energy consumption for Wide Flange beams increase at a greater rate as span length increases as compared to Concrete and Glulam beams At beams lengths of ft, energy consumption is similar for Concrete and Glulam beams with live loads of 45 psf and 100 psf Energy consumption increases as live load on beams increases Energy consumption is highest with Wide Flange as the beam type devoid of live load choice Energy consumption for Wide Flange beams increase at a greater rate as live load increases as compared to Concrete and Glulam beams 8.5 Study 3: Concrete Suspended Slab Span Energy Consumption The intention of this study was to assess the required energy consumption associated with span length of a slab as predicted by the Athena Impact Estimator v4.0 computer program. In this study, the values associated with the columns height, slab width, beam length and beam width (as illustrated in Figure 8.1) were held constant, while the values for slab length and live load were varied Study 3: Input Values Table 8.6 displays all input labels included in this study along with their constant or varied value, a reference to their name and a reference to their applicable figure. Table 8.6 also displays which parameters were varied as applicable. 95

114 Input Reference Name Reference Value Unit Label to Figure Input 1 Figure 14 Gross Floor Area 400 ft 2 Input 2 Figure 14 Building Life Expectancy 50 Years Input 3 Figure 15 Floor Width 20 ft Input 4 Figure 15 Span Varied (15, 20, 25, 28, 30) ft Input 5 Figure 15 Concrete Flyash % Average % Input 6 Figure 15 Concrete 4000 psi Input 7 Figure 15 Live Load Varied (45, 75, 100) psf Input 8 Figure 16 Bay Size 20 ft Input 9 Figure 16 Supported Span 20 ft Input 10 Figure 16 Floor to Floor Height 12 ft Input 11 Figure 16 Live Load 45 psf Input 12 Figure 16 Column Type WF -- Input 13 Figure 16 Beam Type WF -- Table 8.6. Values employed for inputs in study Study 3: Analysis The values provided in Table 8.6 were employed to generate models for each of the varied parameters. The Energy Consumption Absolute Value By Life Cycle Stages output tables for each model from the Athena Impact Estimator are provided in Appendix A3. Table 8.7 provides the total energy consumption values as tabulated from the values provided in Appendix A3 for each varied Span and Live Load by the applicable Bay Size. This table was employed to generate the graphs in Figures 8.15 and

115 Live Live Live 45 psf 75 psf Load Load Load 100 psf Span Span Span Energy Energy Energy Length Length Length (MJ) (MJ) (MJ) (ft) (ft) (ft) Table 8.7. Total energy consumption values for study 3 as provided by the Athena Impact Estimator v4.0 for the applicable input variations Energy Consumption (MJ x 10 3 ) Span Length (ft.) 45 PSF 75 PSF 100 PSF Figure Concrete suspended slab span length vs. total energy consumption 97

116 160.0 Energy Consumption (MJ x 10 3 ) Live Load (psf) 15 ft. Span 20 ft. Span 25 ft. Span 28 ft. Span 30 ft. Span Figure Live load vs. total energy consumption for concrete suspended slab at span lengths of 15, 20, 25, 28 and 30-ft Figures 8.15 displays the relationship between Concrete Suspended Slab span length and Total Energy Consumption that the Athena Impact Estimator v4.0 output tables provide for the three live loads investigated (45 psf, 75 psf, and 100 psf). Figure 8.16 displays the relationship between Live Load and Total Energy Consumption at each the three live loads investigated (45 psf, 75 psf, and 100 psf) for five span lengths (15-ft., 20-ft., 25-ft., 28-ft. and 30-ft.) investigated Study 3: Conclusions The following conclusions have been drawn from the graphs generated in this study: Energy consumption is highest at a live load of 100 psf devoid of slab span length Energy consumption increase as volume of material of a slab increases Energy consumption for live loads of 45 and 75 psf are nearly identical for 98

117 increased span Energy consumption increases as slab span length increases Energy consumption increases as live load on slab increases 8.6 Study 4: Concrete Strength Energy Consumption The intention of this study was to assess the required energy consumption associated with the concrete strength of a slab as predicted by the Athena Impact Estimator v4.0 computer program. In this study, the values associated with the columns height, slab length, slab width, beam length and beam width (as illustrated in Figure 8.1) were held constant, while the values for concrete strength and live load were varied Study 4: Input Values Table 8.8 displays all input labels included in this study along with their constant or varied value, a reference to their name and a reference to their applicable figure Table 8.8 also displays which parameters were varied as applicable. Input Reference Name Reference Value Unit Label to Figure Input 1 Figure 14 Gross Floor Area 400 ft 2 Input 2 Figure 14 Building Life Expectancy 50 Years Input 3 Figure 15 Floor Width 20 ft Input 4 Figure 15 Span 15 ft Input 5 Figure 15 Concrete Flyash % Average % Input 6 Figure 15 Concrete Varied (3000, 4000, 9000) psi Input 7 Figure 15 Live Load Varied (45, 75, 100) psf Input 8 Figure 16 Bay Size 20 ft Input 9 Figure 16 Supported Span 20 ft Input 10 Figure 16 Floor to Floor Height 12 ft Input 11 Figure 16 Live Load 45 psf Input 12 Figure 16 Column Type WF -- Input 13 Figure 16 Beam Type WF -- Table 8.8. Values employed for inputs in study Study 4: Analysis The values provided in Table 8.8 were employed to generate models for each of the varied parameters. The Energy Consumption Absolute Value By Life Cycle Stages output tables for each model from the Athena Impact Estimator are provided in Appendix A4. 99

118 Table 8.9 provides the total energy consumption values as tabulated from the values provided in Appendix A4 for each varied Span and Live Load by the applicable Bay Size. This table was employed to generate the graphs in Figures 8.17 and Live Live Live 45 psf 75 psf Load Load Load 100 psf Concrete Concrete Concrete Energy Energy Energy Strength Strength Strength (MJ) (MJ) (MJ) (psi) (psi) (psi) Table 8.9. Total energy consumption values for study 4 as provided by the Athena Impact Estimator v4.0 for the applicable input variations Energy Consumption (MJ x 10 3 ) Concrete Strength (psi) 45 PSF 75 PSF 100 PSF Figure Concrete suspended slab concrete strength vs. total energy consumption 100

119 Energy Consumption (MJ x 10 3 ) Live Load (psf) 3000 psi 4000 psi 9000 psi Figure Live load vs. total energy consumption for concrete suspended slab at concrete strengths of 3000, 4000 and 9000 psi Figures 8.17 displays the relationship between Concrete Suspended Slab concrete strength and Total Energy Consumption that the Athena Impact Estimator v4.0 output tables provide for the three live loads investigated (45 psf, 75 psf, and 100 psf). Figure 8.18 displays the relationship between Live Load and Total Energy Consumption for each the three live loads investigated (45 psf, 75 psf, and 100 psf) at the three concrete strengths (3000 psi, 4000 psi and 9000 psi) investigated Study 4: Conclusions The following conclusions have been drawn from the graphs generated in this study: Energy consumption increase as concrete strength increases Energy consumption increases are similar for live loads of 45 and 75 psf Energy consumption increases as slab material increases 101

120 Energy consumption for 100 psf live load is the most energy intensive devoid of concrete strength Energy consumption is lower at lower live loads The range between energy consumption relative to concrete strength decreases with higher concrete strength. 8.7 Study 5: Concrete Fly-Ash Percentage Effect on Energy Consumption The intention of this study was to assess the required energy consumption for a slab area relative to concrete fly-ash percentage as predicted by the Athena Impact Estimator v4.0 computer program. In this study, the values associated with the column height, beam width and slab width (as illustrated in Figure 8.1) were held constant. The values for the slab length and beam length were varied to achieve the same floor area for the slab and between the beams. This floor area was also set equal in the initial project parameters interface (see Figure 8.2). The concrete fly-ash percentage was also varied. It should be noted that this is the only study in which beam and slab lengths were varied to match gross floor area Study 5: Input Values Table 8.10 displays the input labels that were held constant in this study as well as their value. Table 8.10 also displays which parameters were varied as applicable. Input Reference to Figure Reference Value Unit Label Input 1 Figure 14 Gross Floor Area Varied (300, 400, 500, 600) ft 2 Input 2 Figure 14 Building Life Expectancy 50 Years Input 3 Figure 15 Floor Width 20 ft Input 4 Figure 15 Span Varied (15, 20, 25, 30) ft Input 5 Figure 15 Concrete Flyash % Varied (average, 25%, 35%) % Input 6 Figure 15 Concrete 4000 psi Input 7 Figure 15 Live Load Varied (45, 75, 100) psf Input 8 Figure 16 Bay Size Varied (15, 20, 25, 30) ft Input 9 Figure 16 Supported Span 20 ft Input 10 Figure 16 Floor to Floor Height 12 ft Input 11 Figure 16 Live Load 45 psf Input 12 Figure 16 Column Type WF -- Input 13 Figure 16 Beam Type WF -- Table Values employed for inputs in study 3 102

121 8.7.2 Study 5: Analysis The values provided in Table 8.10 were employed to generate models for each of the varied parameters. The Energy Consumption Absolute Value By Life Cycle Stages output tables for each model from the Athena Impact Estimator are provided in Appendix A5. Table 8.11 provides the total energy consumption values as tabulated from the values provided in Appendix A5 for each varied Concrete Flyash % and Live Load by the applicable Gross Floor Area. This table was employed to generate the graphs in Figures 8.19 through

122 Live Load 45 psf Live Load 75 psf Live Load 100 psf Flyash % Average Flyash % Average Flyash % Average Floor Area (ft 2 ) Energy (MJ) Floor Area (ft 2 ) Energy (MJ) Floor Area (ft 2 ) Energy (MJ) Flyash % 25% Flyash % 25% Flyash % 25% Floor Area (ft 2 ) Energy (MJ) Floor Area (ft 2 ) Energy (MJ) Floor Area (ft 2 ) Energy (MJ) Flyash % 35% Flyash % 35% Flyash % 35% Floor Area (ft 2 ) Energy (MJ) Floor Area (ft 2 ) Energy (MJ) Floor Area (ft 2 ) Energy (MJ) Table Total energy consumption values for study 3 as provided by the Athena Impact Estimator v4.0 for the applicable input variations 104

123 Energy Consumption (MJ x 10 3 ) Gross Floor Area (ft 2 ) 25% 35% Figure Gross floor area vs. total energy consumption at a live load of 45 psf Energy Consumption (MJ x 10 3 ) Gross Floor Area (ft 2 ) 25% 35% Figure Gross floor area vs.total energy consumption at a live load of 75 psf 105

124 Energy Consumption (MJ x 10 3 ) Gross Floor Area (ft 2 ) 25% 35% Figure Gross floor area vs. total energy consumption at a live load of 100 psf Energy Consumption (MJ x 10 3 ) Live Load (psf) 25% 35% Figure Live load vs. total energy consumption for concrete suspended slab fly-ash percentages 106

125 Figures 8.19 through 8.21 display the relationship between gross floor area and total energy consumption that the Athena Impact Estimator v4.0 output tables provide for the three concrete fly-ash percentages investigated (average, 25%, 35%) at the live loads investigated (45 psf, 75 psf, and 100 psf) for a Concrete Suspended Slab. Figure 8.22 displays the relationship between live load and total energy consumption for a Concrete Suspended Slab Study 5: Conclusions The following conclusions have been drawn from the graphs generated in this study: Energy consumption decreases as fly-ash percentage increases devoid of live load amount The energy consumption decrease relative to fly-ash percentage is greater at larger floor areas Energy consumption decreases for all fly-ash percentages as when live load is increased Energy consumption for 100 psf live load is the most energy intensive devoid of fly-ash percentage 8.8 Concluding Remarks All studies conducted in this chapter employed output data from The Athena Impact Estimator. Microsoft excel was employed for data manipulation. No other computer program was employed in this analysis. Due to this, all finding and conclusions made in these studies are subject to any inherent limitations included in The Athena Impact Estimator. Conclusions about beams, columns, slabs, spans, concrete strengths, live loads, fly-ash percentages lengths and heights all refer to The Athena Impact Estimator inputs and any and all definitions associated with them. 107

126 Chapter 9: Conclusions, Limitations and Recommendations 9.1 Summary and Concluding Remarks Sustainability, as defined by the World Commission on Environment and Development of the United Nations (1987), is achieved by meeting the needs of the present without compromising the ability of the future generations to meet their own needs. In response to this, the engineering community has been working to develop accurate methods for determining and comparing the sustainability of design alternatives. This study investigated the issues involved in achieving sustainable designs for projects structural systems and assessed some of the measurement methods currently in use. Five potential sustainable structural design methodologies are presented: Minimizing Material Use, Minimizing Material Production Energy, Minimizing Embodied Energy, Life-Cycle Analysis/Inventory/Assessment and Maximizing Structural Reuse. Each design methodology reviewed in Chapter 3 defines sustainability in structural design in a unique way and looks to employ that unique definition in assessing and achieving the most sustainable design. However, use of any single design methodology can limit project sustainability, as outline in Table 3.1. Review of these five potential solutions for the problem of achieving a sustainable structural design, and their positive and negative sustainable qualities, displays that no one methodology can guarantee the most sustainable design. It is suggested that the use of two or more design methodologies is more advantageous to sustainable design as the positive qualities of one methodology can offset the negative qualities of another. The categories of the 2009 Leadership in Energy and Environmental Design (LEED) rating system are reviewed to see which points could be awarded to a project to improve sustainability of its structural frame. Chapter 4 describes the aspects of design related to its structural system for which a project can receive up to 10 rating points. These points account for ten percent of the total possible points that can be awarded in 108

127 the LEED rating system. Illustrated by the low percentage of points that can be earned by a structural system in LEED is the lack of weight that this rating systems give to this aspect of design. It can be inferred from this that were more importance to be placed on the sustainable design of structural frames in the LEED rating system, more efficient designs and thus overall higher project sustainability would result. Thus, the LEED rating system has little effect on structural system sustainability and can negatively affect overall project sustainability. Also, demolition, maintenance and durability requirements are not considered in LEED. The role that project size and structural system-type play on aspects of sustainable design are presented. Design and analysis phase, land use, investments in sustainable technologies, use of wood as a primary load bearing material are some of the critical issues discussed in Chapter 5. Reviews of the effect that project size and structural system-type can have on these aspects of design displays that they are closely tied to overall project sustainability. During initial project design, attention to the impact that increased project size has on structural system material requirements as well as overall project sustainable is important. Designers and owners should consider the implications that selection of one design alternative over another can have relative to its ability to achieve a successful sustainable design. Structurally applicable sustainable properties associated with structural steel, castin-place and prestessed/precast concrete are reviewed. Each material presents unique sustainable qualities that can be advantageous to sustainable design. However, each material also presents unique construction requirements, by-product emissions and impact of project operation and maintenance. It was concluded that no single construction material discussed in Chapter 6 guarantees that the most sustainable design will be achieved. Use of different materials for a structural system can contribute to overall project sustainability but the combination can prove to be less sustainable. It is suggested that designers consider multiple design alternatives paying close attention to project location and material availability. A review of life-cycle analysis computer programs (e.g. Building for Environmental and Economic Sustainability (BEES) v4.0, SimaPRO v7.1 and Athena 109

128 Impact Estimator v4.0) was conducted to assess the sustainability of design alternatives. This review displays that the reviewed life-cycle analysis programs do not provide users with definite conclusions about design alternative sustainability. Potential inaccuracy included in internal program tables, limiting raw material input choices and analysis methods that do not accurately changes in design alternatives all contribute to this. It can thus be concluded that current design alternative comparison programs do not meet the basic needs of engineers in determining structural sustainability. Structural system sustainability has many issues that can be affected by all aspects of project design. Accurate prediction of the sustainability of design alternatives relies heavily on accuracy of the data provided by industry. Thus the current analysis tools and methodologies may be inaccurate. To increase overall project and structural system sustainability, consideration to the role that structural systems play and the impact that they can on overall project sustainable properties must be given. More accurate and encompassing industry data is required to assess design alternative s sustainability. Current sustainable rating systems should also include the role that a project s structural system plays in sustainability as well as how raw material requirements and material production energies contribute to the overall sustainable properties of a project. Parametric studies using the Athena Impact Estimator v4.0 can be employed to investigate relationships between energy consumption and structural systems. Energy consumption of structural members varies depending on their material type and length. The energy consumption associated with columns, beams, slabs, concrete strength and fly-ash percentage are unique in their response to changes in live load and system geometry. The program s internal analysis tools limit any conclusions drawn from use of the Athena Impact Estimator. 9.2 Conclusions This study has concluded the following: No single current sustainable design methodology can address all project sustainability issues at this time. The LEED 2009 rating system does not reward projects for sustainable design of their structural systems in the same manner it does other aspects of design. 110

129 Construction type and project size can have significant impact on sustainable opportunities for a project. No single construction material is the most sustainable compared to others for all design types at this time. Existing sustainability analysis software does not meet the current needs of its users in assessing design alternative sustainable properties. Use of the Athena Impact Estimator can provide insights into the relationship between energy consumption and structural system member types but is limited by the internal program analysis methods and definitions. 9.3 Limitations This study has been limited by the following: Lack of previous research involving the application of each of the aforementioned design methodologies simultaneously. Lack and difficultly of the development of equations and methods for completing each of the proposed methodologies within a structural design. Lack of research providing quantitative values on the effect that project size and 3 Inaccurate or limiting data on total production inputs and energy requirements for construction materials. The limited number and accuracy of tools and computer programs to assess sustainable design alternative. 9.4 Recommendations The following suggestions were outside the scope of this thesis and suggested as recommendations for future research: The analysis of various structures of different size and material choice to determine the overall production energies inputs and values associated with each. Investigation of use of each of the design methodologies suggested for comparative structures separately as well as in combination. Careful review of the LEED rating system s importance and impact on sustainable designs from a structural perspective be conducted including investigation into what LEED ratings can be achieved following the any (or any 111

130 combination of the mentioned design methodologies. The development of a more accurate sustainable design alternative assessment computer program or other tools that can be used by engineers. 112

131 References ASTM International. ASTM E : Standard Practice for Measuring Life Cycle of Building and Building Systems. Book of ASTM Standards, ASTM International. ASTM E : Internal Rate of Return and Adjusted Internal Rate of Return for Investments. Book of ASTM Standards, ASTM International. ASTM E : Net Benefits and Net Savings for Investments. Book of ASTM Standards, ASTM International. ASTM E : Measuring Payback. Book of ASTM Standards, ASTM International. ASTM E : Economic Methods for Evaluating Investments. Book of ASTM Standards, ASTM International. ASTM E : Standard Guide for Summarizing the Economic Impacts of Building-Related. Book of ASTM Standards, Beheiry, S. M. A., Chong, W. K., and Haas, C. T. Examining the Business Impact of Owner Commitment to Sustainability. Journal of Construction Engineering and Management, Vol. 132, No. 4, 2006, pp Deane, M. The Builder s Role in Delivering Sustainable Tall Buildings. The Structural Design of Tall and Special Buildings, Vol. 17, No. 5, 2008, pp Elnimeri, M. and Gupta, P. Sustainable Structure of Tall Buildings. The Structural Design of Tall and Special Buildings, Vol. 17, No. 5, 2008, pp Fruehan, R.J., Fortinti, O., Paxton, H.W. and Brindle, R. Theoretical Minimum Energies to Produce Steel for Selected Conditions. U.S. Department of Energy Horvath, A. and Hendrickson, C. Steel versus Steel-Reinforced Concrete Bridges: Environmental Assessment. Journal of Infrastructure Systems, Vol. 4, No. 3, 1998, pp Kestner, D. M. Sustainable Design. Structure Magazine, 2007, pp. 7 Laefer, D. and Manke, J. Building Reuse Assessment for Sustainable Urban Reconstruction. Journal of Construction Engineering and Management, Vol. 134, No. 3, 2008, pp

132 Moon, K. Material-Saving Design Strategies for Tall Building Structures. Proceedings: Tall & Green: Typology for a Sustainable Urban Future: CTBUH 8th World Congress, Dubai, March Moon, K. S. Sustainable Structural Engineering Strategies for Tall Buildings. The Structural Design of Tall and Special Buildings, Vol. 17, No. 5, 2008, pp Naik, T. Sustainability of Concrete Construction. Practice Periodical on Structural Design and Construction, Vol. 13, No. 2, 2008, pp National Institute of Standards and Technology. Building for Environmental and Economic Sustainability Technical Manual and User Guide, Penttala, V. Concrete and Sustainable Development. ACI Materials Journal, Vol. 94, No. 5, 1997, pp Price, L., Sinton, J., Worrell, E., Phylipsen, D., Xiulian, H. and Ji, L. Energy Use and Carbon Dioxide Emissions from Steel Production in China. Lawrence Berkley National Laboratory, 2001, pp Shi, J. and Han, T. Conceiving Methods and Innovative Approaches for Tall Building Structure Systems. The Structural Design of Tall and Special Buildings, 2009, Early View. Szekely, J. Steelmaking and Industrial Ecology-Is Steel a Green Material. ISIJ International, V. 36, No. 1, 1996, pp Trabucco, D. An Analysis of the Relationship between Service Cores and the Embodied/Running Energy of Tall Buildings. The Structural Design of Tall and Special Buildings, Vol. 17, No. 5, 2008, pp The United States Department of Energy. Building Energy Software Tools Directory, Building Technologies Program, < ubjects/pagename_menu=materials_components/pagename_submenu=hvac_syste ms>, September The United State Department of Energy. Energy Use in Manufacturing. Energy Information Administration, October The United State Green Building Council, < March The United States Green Building Council, LEED 2009 for New Construction and Major Renovations

133 VanGeem, M. Designer s Notebook: Sustainable Design. Ascent Magazine, 2006, pp Wood, A. Sustainability: A New High-Rise Vernacular? The Structural Design of Tall and Special Buildings, Vol. 16, No. 4, 2007, pp Worrell, E., Price, L. and Martin, N. Energy Efficiency and Carbon Dioxide Emissions Reduction Opportunities in the US Iron and Steel Sector. Lawrence Berkley National Laboratory,

134 Appendix A1: Athena Impact Estimator Output Tables for Study 1 116

135 Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = Concrete, PSF = 45, Column Height = 10 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total 117 Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = Concrete, PSF = 45, Column Height = 11 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

136 Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = Concrete, PSF = 45, Column Height = 12 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = Concrete, PSF = 45, Column Height = 13 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

137 Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = Concrete, PSF = 45, Column Height = 14 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = Concrete, PSF = 45, Column Height = 15 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

138 Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = WF, PSF = 45, Column Height = 10 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = WF, PSF = 45, Column Height = 11 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

139 Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = WF, PSF = 45, Column Height = 12 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = WF, PSF = 45, Column Height = 13 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

140 Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = WF, PSF = 45, Column Height = 14 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = WF, PSF = 45, Column Height = 15 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

141 Energy Consumption Absolute Value Table By Life Cycle Stages Wood MJ Column Type = Glulam, PSF = 45, Column Height = 10 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Wood MJ Column Type = Glulam, PSF = 45, Column Height = 11 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

142 Energy Consumption Absolute Value Table By Life Cycle Stages Wood MJ Column Type = Glulam, PSF = 45, Column Height = 12 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Wood MJ Column Type = Glulam, PSF = 45, Column Height = 13 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

143 Energy Consumption Absolute Value Table By Life Cycle Stages Wood MJ Column Type = Glulam, PSF = 45, Column Height = 14 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Wood MJ Column Type = Glulam, PSF = 45, Column Height = 15 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

144 Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = Concrete, PSF = 75, Column Height = 10 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = Concrete, PSF = 75, Column Height = 11 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

145 Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = Concrete, PSF = 75, Column Height = 12 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = Concrete, PSF = 75, Column Height = 13 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

146 Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = Concrete, PSF = 75, Column Height = 14 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = Concrete, PSF = 75, Column Height = 15 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

147 Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = WF, PSF = 75, Column Height = 10 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = WF, PSF = 75, Column Height = 11 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

148 Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = WF, PSF = 75, Column Height = 12 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = WF, PSF = 75, Column Height = 13 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

149 Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = WF, PSF = 75, Column Height = 14 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = WF, PSF = 75, Column Height = 15 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

150 Energy Consumption Absolute Value Table By Life Cycle Stages Wood MJ Column Type = Glulam, PSF = 75, Column Height = 10 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Wood MJ Column Type = Glulam, PSF = 75, Column Height = 11 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

151 Energy Consumption Absolute Value Table By Life Cycle Stages Wood MJ Column Type = Glulam, PSF = 75, Column Height = 12 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Wood MJ Column Type = Glulam, PSF = 75, Column Height = 13 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

152 Energy Consumption Absolute Value Table By Life Cycle Stages Wood MJ Column Type = Glulam, PSF = 75, Column Height = 14 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Wood MJ Column Type = Glulam, PSF = 75, Column Height = 15 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

153 Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = Concrete, PSF = 100, Column Height = 10 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = Concrete, PSF = 100, Column Height = 11 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

154 Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = Concrete, PSF = 100, Column Height = 12 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = Concrete, PSF = 100, Column Height = 13 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

155 Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = Concrete, PSF = 100, Column Height = 14 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = Concrete, PSF = 100, Column Height = 15 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

156 Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = WF, PSF = 100, Column Height = 10 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = WF, PSF = 100, Column Height = 11 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

157 Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = WF, PSF = 100, Column Height = 12 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = WF, PSF = 100, Column Height = 13 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

158 Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = WF, PSF = 100, Column Height = 14 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Column Type = WF, PSF = 100, Column Height = 15 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

159 Energy Consumption Absolute Value Table By Life Cycle Stages Wood MJ Column Type = Glulam, PSF = 100, Column Height = 10 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Wood MJ Column Type = Glulam, PSF = 100, Column Height = 11 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

160 Energy Consumption Absolute Value Table By Life Cycle Stages Wood MJ Column Type = Glulam, PSF = 100, Column Height = 12 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total 142 Energy Consumption Absolute Value Table By Life Cycle Stages Wood MJ Column Type = Glulam, PSF = 100, Column Height = 13 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

161 Energy Consumption Absolute Value Table By Life Cycle Stages Wood MJ Column Type = Glulam, PSF = 100, Column Height = 14 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Wood MJ Column Type = Glulam, PSF = 100, Column Height = 15 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

162 Appendix A2: Athena Impact Estimator Output Tables for Study 2 144

163 Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = WF, Live Load = 45 PSF, Beam Length = 15 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = WF, Live Load = 45 PSF, Beam Length = 20 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

164 Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = WF, Live Load = 45 PSF, Beam Length = 25 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total 146 Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = WF, Live Load = 45 PSF, Beam Length = 30 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

165 Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = WF, Live Load = 45 PSF, Beam Length = 40 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total 147 Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = Concrete, Live Load = 45 PSF, Beam Length = 15 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

166 Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = Concrete, Live Load = 45 PSF, Beam Length = 20 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = Concrete, Live Load = 45 PSF, Beam Length = 25 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

167 Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = Concrete, Live Load = 45 PSF, Beam Length = 30 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = Concrete, Live Load = 45 PSF, Beam Length = 40 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

168 Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = Glulam, Live Load = 45 PSF, Beam Length = 15 Wood MJ Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = Glulam, Live Load = 45 PSF, Beam Length = 20 Wood MJ Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

169 Energy Consumption Absolute Value Table By Life Cycle Stages Wood MJ Beam Type = Glulam, Live Load = 45 PSF, Beam Length = 25 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total 151 Energy Consumption Absolute Value Table By Life Cycle Stages Wood MJ Beam Type = Glulam, Live Load = 45 PSF, Beam Length = 30 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

170 Energy Consumption Absolute Value Table By Life Cycle Stages Wood MJ Beam Type = Glulam, Live Load = 45 PSF, Beam Length = 40 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = WF, Live Load = 75 PSF, Beam Length = 15 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

171 Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = WF, Live Load = 75 PSF, Beam Length = 20 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = WF, Live Load = 75 PSF, Beam Length = 25 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

172 Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = WF, Live Load = 75 PSF, Beam Length = 30 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total 154 Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = WF, Live Load = 75 PSF, Beam Length = 40 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

173 Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = Concrete, Live Load = 75 PSF, Beam Length = 15 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = Concrete, Live Load = 75 PSF, Beam Length = 20 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

174 Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = Concrete, Live Load = 75 PSF, Beam Length = 25 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = Concrete, Live Load = 75 PSF, Beam Length = 30 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

175 Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = Concrete, Live Load = 75 PSF, Beam Length = 40 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total 157 Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = Glulam, Live Load = 75 PSF, Beam Length = 15 Wood MJ Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

176 Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = Glulam, Live Load = 75 PSF, Beam Length = 20 Wood MJ Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Wood MJ Beam Type = Glulam, Live Load = 75 PSF, Beam Length = 25 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

177 Energy Consumption Absolute Value Table By Life Cycle Stages Wood MJ Beam Type = Glulam, Live Load = 75 PSF, Beam Length = 30 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Wood MJ Beam Type = Glulam, Live Load = 75 PSF, Beam Length = 40 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

178 Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = WF, Live Load = 100 PSF, Beam Length = 15 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = WF, Live Load = 100 PSF, Beam Length = 20 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total

179 Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = WF, Live Load = 100 PSF, Beam Length = 25 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = WF, Live Load = 100 PSF, Beam Length = 30 Manufacturing Construction Maintenance End - Of - Life Operating Energy Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total Total

180 Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = WF, Live Load = 100 PSF, Beam Length = 40 Manufacturing Construction Maintenance End - Of - Life Operating Energy Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total Total 162 Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = Concrete, Live Load = 100 PSF, Beam Length = 15 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total

181 Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = Concrete, Live Load = 100 PSF, Beam Length = 20 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = Concrete, Live Load = 100 PSF, Beam Length = 25 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total

182 Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = Concrete, Live Load = 100 PSF, Beam Length = 30 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = Concrete, Live Load = 100 PSF, Beam Length = 40 Manufacturing Construction Maintenance End - Of - Life Operating Energy Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total Total

183 Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = Glulam, Live Load = 100 PSF, Beam Length = 15 Wood MJ Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total Energy Consumption Absolute Value Table By Life Cycle Stages Beam Type = Glulam, Live Load = 100 PSF, Beam Length = 20 Wood MJ Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total

184 Energy Consumption Absolute Value Table By Life Cycle Stages Wood MJ Beam Type = Glulam, Live Load = 100 PSF, Beam Length = 25 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total Energy Consumption Absolute Value Table By Life Cycle Stages Wood MJ Beam Type = Glulam, Live Load = 100 PSF, Beam Length = 30 Manufacturing Construction Maintenance End - Of - Life Operating Energy Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total Total

185 Energy Consumption Absolute Value Table By Life Cycle Stages Wood MJ Beam Type = Glulam, Live Load = 100 PSF, Beam Length = 40 Manufacturing Construction Maintenance End - Of - Life Operating Energy Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total Total 167

186 Appendix A3: Athena Impact Estimator Output Tables for Study 3 168

187 Energy Consumption Absolute Value Table By Life Cycle Stages Floor Type = Concrete Suspended Slab, Live Load = 45 PSF, Span Length = 15 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Floor Type = Concrete Suspended Slab, Live Load = 45 PSF, Span Length = 20 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

188 Energy Consumption Absolute Value Table By Life Cycle Stages Floor Type = Concrete Suspended Slab, Live Load = 45 PSF, Span Length = 25 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Floor Type = Concrete Suspended Slab, Live Load = 45 PSF, Span Length = 28 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

189 Energy Consumption Absolute Value Table By Life Cycle Stages Floor Type = Concrete Suspended Slab, Live Load = 45 PSF, Span Length = 30 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total 171 Energy Consumption Absolute Value Table By Life Cycle Stages Floor Type = Concrete Suspended Slab, Live Load = 75 PSF, Span Length = 15 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

190 Energy Consumption Absolute Value Table By Life Cycle Stages Floor Type = Concrete Suspended Slab, Live Load = 75 PSF, Span Length = 20 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Floor Type = Concrete Suspended Slab, Live Load = 75 PSF, Span Length = 25 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

191 Energy Consumption Absolute Value Table By Life Cycle Stages Floor Type = Concrete Suspended Slab, Live Load = 75 PSF, Span Length = 28 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Floor Type = Concrete Suspended Slab, Live Load = 75 PSF, Span Length = 30 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

192 Appendix A4: Athena Impact Estimator Output Tables for Study 4 174

193 Energy Consumption Absolute Value Table By Life Cycle Stages Floor Type = Concrete Suspended Slab, Live Load = 45 PSF, Concrete Strength = 3000 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total 175 Energy Consumption Absolute Value Table By Life Cycle Stages Floor Type = Concrete Suspended Slab, Live Load = 45 PSF, Concrete Strength = 4000 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

194 Energy Consumption Absolute Value Table By Life Cycle Stages Floor Type = Concrete Suspended Slab, Live Load = 45 PSF, Concrete Strength = 9000 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total 176 Energy Consumption Absolute Value Table By Life Cycle Stages Floor Type = Concrete Suspended Slab, Live Load = 75 PSF, Concrete Strength = 3000 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

195 Energy Consumption Absolute Value Table By Life Cycle Stages Floor Type = Concrete Suspended Slab, Live Load = 75 PSF, Concrete Strength = 4000 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total 177 Energy Consumption Absolute Value Table By Life Cycle Stages Floor Type = Concrete Suspended Slab, Live Load = 75 PSF, Concrete Strength = 9000 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

196 Energy Consumption Absolute Value Table By Life Cycle Stages Floor Type = Concrete Suspended Slab, Live Load = 100 PSF, Concrete Strength = 3000 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Floor Type = Concrete Suspended Slab, Live Load = 100 PSF, Concrete Strength = 4000 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

197 Energy Consumption Absolute Value Table By Life Cycle Stages Floor Type = Concrete Suspended Slab, Live Load = 100 PSF, Concrete Strength = 9000 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total 179

198 Appendix A5: Athena Impact Estimator Output Tables for Study 5 180

199 Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = Average, PSF = 45, Gross Floor Area = 300 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = Average, PSF = 45, Gross Floor Area = 400 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total

200 Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = Average, PSF = 45, Gross Floor Area = 500 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = Average, PSF = 45, Gross Floor Area = 600 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

201 Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = 25%, PSF = 45, Gross Floor Area = 300 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = 25%, PSF = 45, Gross Floor Area = 400 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

202 Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = 25%, PSF = 45, Gross Floor Area = 500 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = 25%, PSF = 45, Gross Floor Area = 600 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

203 Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = 35%, PSF = 45, Gross Floor Area = 300 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total 185 Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = 35%, PSF = 45, Gross Floor Area = 400 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

204 Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = 35%, PSF = 45, Gross Floor Area = 500 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = 35%, PSF = 45, Gross Floor Area = 600 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total

205 Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = Average, PSF = 75, Gross Floor Area = 300 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = Average, PSF = 75, Gross Floor Area = 400 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total

206 Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = Average, PSF = 75, Gross Floor Area = 500 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = Average, PSF = 75, Gross Floor Area = 600 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total

207 Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = 25%, PSF = 75, Gross Floor Area = 300 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = 25%, PSF = 75, Gross Floor Area = 400 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total

208 Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = 25%, PSF = 75, Gross Floor Area = 500 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = 25%, PSF = 75, Gross Floor Area = 600 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total

209 Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = 35%, PSF = 75, Gross Floor Area = 300 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = 35%, PSF = 75, Gross Floor Area = 400 Manufacturing Construction Maintenance End - Of - Life Operating Energy Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total Total

210 Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = 35%, PSF = 75, Gross Floor Area = 500 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = 35%, PSF = 75, Gross Floor Area = 600 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total

211 Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = Average, PSF = 100, Gross Floor Area = 300 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = Average, PSF = 100, Gross Floor Area = 400 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total

212 Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = Average, PSF = 100, Gross Floor Area = 500 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = Average, PSF = 100, Gross Floor Area = 600 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total

213 Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = 25%, PSF = 100, Gross Floor Area = 300 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = 25%, PSF = 100, Gross Floor Area = 400 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total

214 Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = 25%, PSF = 100, Gross Floor Area = 500 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = 35%, PSF = 100, Gross Floor Area = 300 Manufacturing Construction Maintenance End - Of - Life Operating Energy Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total Total

215 Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = 35%, PSF = 100, Gross Floor Area = 400 Manufacturing Construction Maintenance End - Of - Life Operating Energy Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total Total 197 Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = 35%, PSF = 100, Gross Floor Area = 500 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total

216 Energy Consumption Absolute Value Table By Life Cycle Stages Concrete Flyash % = 35%, PSF = 100, Gross Floor Area = 600 Manufacturing Construction Maintenance End - Of - Life Operating Energy Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Material Transport-ation Total Annual Total Material Transport-ation Total