Construction Alternatives: What Life Cycle Assessment Reveals

Transcription

1 National Sponsors Environmental Impacts of Construction Alternatives: What Life Cycle Assessment Reveals Jim Bowyer Dovetail Partners, Inc. Minneapolis, MN The Wood Products Council is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES). Credit(s) earned on completion of this program will be reported to AIA/CES for AIA members. Certificates of Completion for both AIA members and non-aia members are available upon request. This program is registered with AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product. Copyright Materials This presentation is protected by US and International Copyright laws. Reproduction, distribution, display and use of the presentation without written permission of the speaker is prohibited. The Wood Products Council 2012

2 Learning Objectives Understand d the nature of systematic ti assessment using life cycle analysis and its increasing use in green building programs and model codes. Learn outcomes of multiple life cycle comparisons of various construction alternatives. Recognize the elements that are needed for valid life cycle comparisons. Become knowledgeable about Environmental Product Declarations (EPDs) and how they can be used in materials selection decisions. Life Cycle Analysis Life Cycle Analysis Life Cycle Analysis A systematic accounting of environmental impacts linked to a product or process. Define Scope Measure (Inventory) Evaluate (Impact Assessment) Consider Improvements (Improvement Assessment)

3 2 Life Cycle Inventory (LCI) Examination of all measurable: Raw material inputs Products and by-products Emissions i Effluents Wastes 2 Life Cycle Inventory (LCI) Typically involves all stages in production, use, anddisposal, including: Extraction Transportation Primary processing Conversion to semi-finished products Incorporation into finished products Maintenance Disposal/reuse Acetaldehyde Acetone Acrolein Benzene Carbon dioxide (fossil) Carbon dioxide (non-fossil) Carbon monoxide Methane SO 2, SO 3 NO x VOCs Inventory Organic substances Arsenic Cyanide Phenols Sulfides Ammonia Oil and grease Particulates Suspended solids Non-ferrous metals Dust (PM10) And hundreds to thousands of other compounds. Impact Assessment Embodied energy (GJ) GWP (CO 2 kg) Air emission index Acidification potential Human toxicity Photochemical oxidation Ozone layer depletion Depletion of non-renewable resources Water consumption Eutrophication Solid waste (total kg)

4 Improvement Assessment Reduce energy consumption? Reduce fossil fuel consumption? Use substitute materials? Source raw materials locally? Improve processes? Redesign product? Enhance product life, durability? Reduce maintenance requirements? Reduce packaging? Improve waste management? Improvement Assessment Increase energy efficiency of bldg? Reduce embodied energy? Use substitute building materials? Source building materials locally? Improve construction processes? Redesign building? Enhance building life, durability? Reduce building maintenance needs? Reduce packaging of mat ls delivered to building site? Improve construction waste mgmt? Innovative options: Use a life-cycle assessment (LCA) tool to compare the environmental burden of building materials and, based on the analysis, use the most environmentally preferable product for that building component. Voluntary Tier I, Tier II A Materials and system assemblies. Select materials assemblies based on life cycle assessment of their embodied energy and/or green house gas emission potentials.

5 ASHRAE Use of Reduced Impact Materials Either the prescriptive path for reduced impact materials or the performance path for a life cycle assessment (LCA) must be followed. The intent of both is to reduce the impact of construction materials used in the building on natural resources and minimize their environmental impact. ASHRAE The performance path requires that an LCA be performed on a base building and the proposed project building. The LCA must be performed in accordance ISO Standard Whole building life cycle assessment project elective. A whole building life cycle assessment shall be a project elective. IGCC The assessment shall demonstrate that the building project achieves not less than a 20 percent improvement in environmental performance for each of at least three of the following impact measures, one of which shall be global warming potential Primary energy use 1.2 Global warming potential 1.3 Acidification potential 1.4 Eutrophication potential 1.5 Ozone depletion potential 1.6 Smog potential

6 Life Cycle Comparisons of Construction Alternatives Wälludden Project, Växjo, Sweden Department e t of Ecotechnology, o ogy, Mid-Sweden University, Östersund, Sweden (2000) Wälludden Project, Växjo, Sweden Wälludden Project, Växjo, Sweden Designed and built in wood. Life cycle analysis (LCA) of environmental impacts LCA of identical building built of concrete. Four-story apartment buildings, each containing 16 apartments. Total usable floor area in each building of 12,809 ft 2.

7 Wälludden Project, Växjo, Sweden Materials Use in the Buildings (mt) Material Wood Concrete Lumber Particleboard 18 9 Plywood 21 0 Concrete Plasterboard Wälludden Project, Växjo, Sweden Wood Concrete Difference Energy Consumption in Building Materials Production Total energy consumed in producing construction materials (GJ) % CO2 Emissions Over Building Life Cycle (mt CO2e) Fossil fuel use in mat l production % Emission from cement reactions 1/ % 1/ It was assumed that 8% of CO2 emissions from calcination reactions would be reabsorbed by the concrete over a 100-year building life. Wälludden Project, Växjo, Sweden Wood Concrete Difference Energy Consumption in Building Materials Production Total energy consumed in producing construction materials (GJ) % CO2 Emissions Over Building Life Cycle (mt CO2e) Fossil fuel use in mat l production % Emission from cement reactions 1/ % Long-Term Carbon Storage in Building Materials (mt) Carbon stock in building materials % Avoided Carbon Emissions Due to Displacement of Fossil Fuels Includes biofuel use in building materials production and biofuel recovery at end of life % 1/ It was assumed that 8% of CO2 emissions from calcination reactions would be reabsorbed by the concrete over a 100-year building life. Key Findings: The average greenhouse gas (GHG) mitigation over a 100-year perspective is 2 to 3 times better for the wood building than the concrete building. It is also better over 50-year and 300-year building life cycles. The use of wood building materials in place of concrete, coupled with the greater integration of wood by-products into energy production would be an effective means of reducing fossil fuel use and net CO2 emissions to the atmosphere.

8 Växjo Wooden City Part of an effort initiated in 1996 to become a fossil fuel free city and the greenest city in Europe. Results from the Wälludden Project were the basis for focus on wood construction. Carbon Dioxide Emissions of Various Components in a Typical New Zealand House Carbon Dioxide Emissions of Various Components in a Typical New Zealand House Department of Civil Engineering University of Canterbury Christchurch, New Zealand (1994) Evaluated were energy consumption and carbon emissions associated with production of three single-story single family houses, each built in a different way.

9 Carbon Dioxide Emissions of Various Components in a Typical New Zealand House Timber Steel Concrete Slab New Zealand Also evaluated were single story industrial buildings built of wood and steel, a five- story office building built of wood, steel, or reinforced concrete, a six-story hotel built of either wood or reinforced concrete House Frame Floor Wall Honey and Buchanan, Department of Civil Engineering, University of Canterbury, Christchurch, NZ, Key Finding: The production of wood buildings was found to consistently use less energy and have lower CO 2 emissions than construction of steel and reinforced concrete. Energy Consumption and CO 2 Emissions in Constructing a Large Office Building Athena Sustainable Materials Institute t Ottawa, Canada (1992)

10 Energy Consumption and CO 2 Emissions in Constructing ti a Large Office Building Analysis of a Large Office Building Wood Steel Concrete Life cycle comparison of three designs. Total Energy Above Grade CO 2 Construction Use* Energy Use* Emissions** Wood Steel Concrete * GJ x 10 3 ** kg x 10 3 CaCo 3 CaO + CO 2 Key Findings: Wood building on concrete foundation had embodied energy only 67% of that of concrete and 53% of that of the steel building. Wood building had above grade embodied energy only 59% that of concrete and 42% that of steel building. Carbon emissions associated with wood structure only 60% and 70% of those of concrete and steel structure respectively. FP Innovations Laboratory, Vancouver, B.C.

11 LCA of Residential Homes in Minneapolis and Atlanta Minneapolis House Front Elevation Consortium for Research on Renewable Industrial Materials University of Washington, Seattle (2004) Atlanta House Elevations Design Differences - Minneapolis Wood Frame 2,062 ft 2 two story Steel Frame Exterior Walls with 2x6 16 plywood sheathing 20 ga. 16 2x4 16 Interior Walls - no 25 ga. 16 sheathing Roof all wood Floor - plywood decking 2x ga. 12 Extraction (primary materials) 14,371 kg of Wood 7,737 kg of Wood 1,570 kg of Iron 8,605 kg of Iron

12 Design Differences - Atlanta Wood Frame 2,153 ft 2 one story on slab Concrete 2x4 16 Exterior Walls concrete blocks plywood sheathing Interior Walls 2x4 16 no sheathing 2x4 16 Roof all wood Floor - slab Extraction (primary materials) 11,498 kg of Wood 8,397 kg of Wood 8,388 kg of Limestone 14,487 kg of Limestone Performance Indices Minneapolis Home Total Structure Wood Frame Steel Frame Difference Steel vs. Wood (% Change) Embodied energy (GJ) % GWP (CO 2 kg) 37,047 46,826 9, % Air (index scale) 8,566 9,729 1, % Water (index scale) % Solid Waste (kg) 13,766 13, % Above Grade Walls Wood Frame Steel Frame Difference Steel vs. Wood (% Change) Embodied energy (GJ) % GWP (CO 2 kg) 13,009 17,262 4, % Air (index scale) 3,820 4, % Water (index scale) % Solid Waste (kg) 3,496 3, % Fossil Fuel Consumption Minneapolis Home Exterior Walls (MJ/ft. 2 ) Steel vs. Wood Wood Wall Steel Wall Difference (% Change) Structural % Insulation % Cladding % Total % Performance Indices Atlanta Home Total Structure Wood Frame Concrete Frame Difference Conc. vs. Wood (% Change) Embodied energy (GJ) % GWP (CO 2 kg) 21,367 28,004 6, % Air (index scale) 4,893 6,007 1, % Water (index scale) % Solid Waste (kg) 7,442 11,269 3, % Above Grade Walls Wood Frame Concrete Frame Difference Conc. vs. Wood (% Change) Embodied d energy (GJ) % GWP (CO 2 kg) 8,345 14,982 6, % Air (index scale) 2,313 3,373 1, % Water (index scale) % Solid Waste (kg) 2,325 6, %

13 Fossil Fuel Consumption Atlanta Home Exterior Walls (MJ/ft. 2 ) Concrete Steel vs. Wood Wood Wall Wall Difference (% Change) Structural ,015% Insulation % Cladding % Total % Fossil Fuel Consumption Atlanta Home Alternative Floor Designs (MJ fossil fuels/ft. 2 ) Dimension wood joist floor Concrete slab floor Steel joist floor Total Key Findings: Wood substitution for steel and concrete in home building consistently reduces energy consumption, fossil energy depletion, emissions of greenhouse gases and other emissions to air and water. Wood construction leads to greater quantities of construction waste than steel construction, but far lower solid waste generation than concrete construction. Energy Consumption and CO 2 Emissions in Constructing the Roof of Oslo International Airport Terminal Agricultural l University it of Norway Oslo, Norway (2002)

14 Energy Consumption and CO 2 Emissions in Constructing the Roof of Oslo International Airport Terminal Compared energy consumption and GHG emissions associated with two options for construction of the roof structure: steel beams and glue-laminated spruce wood beams. Key Findings: Manufacturing steel beams uses 2 to 3 times more energy and 6 to 12 times more fossil fuels than manufacturing glulam beams. If virgin, rather than recycled, steel is used, the differences as indicated above become substantially greater. In the most likely scenario, steel beam manufacture results in 5 times greater GHG emissions than does the manufacture of glulam beams. Energy Consumption in Construction of Warehouses Made of Wood, Steel, and Concrete Energy Consumption and GWP Associated with Construction of Alternative Warehouse Designs Wood Steel Concrete Energy (incl. operational energy) - GJ 5,330 6,580 8,000 GWP (mt CO 2 e) 1,030* 1,320 1,600 Federal Research Centre for Forestry and Forest Products Hamburg, Germany (2003) * If wood is recovered for energy generation at the end of building life, the GWP for the wood design drops to 829 mt.

15 Key Findings: In a series of life cycle assessments of buildings and building components made of wood and non-wood materials, production of wood alternatives consistently used less energy and emitted less GHG than non-wood materials. Caution Advised When Considering LCA Results When selecting an LCA tool for use in evaluation of construction alternatives, ti or when interpreting ti an article in the media about LCA findings, it is important to consider three essential elements. e e 1. A Life Cycle Analysis should be done in compliance with ISO 14040, and involve independent third party oversight and review.

16 Scope (System Boundary) 2. When comparing products using LCA, the scope of the life cycle considered is important. All critical elements Same scope for all included products compared RECOVERED STEEL OTHER MATERIALS ENERGY WATER Mining Crushing/Separation Refining Smelting Forming Steel Products Mfg Building Construction Use/Maintenance Recycling/Waste Mgmt EMISSIONS EFFLUENTS SOLID WASTES OTHER RELEASES PRODUCTS COPRODUCTS Scope (System Boundary) Mining RECOVERED STEEL OTHER MATERIALS ENERGY WATER Crushing/Separation Refining Smelting Forming Steel Products Mfg Building Construction EMISSIONS EFFLUENTS SOLID WASTES OTHER RELEASES PRODUCTS COPRODUCTS 3. When comparing products, the comparison must be of functionally equivalent products. Use/Maintenance Recycling/Waste Mgmt

17 The Role of Environmental Product Declarations Environmental Product Declaration (EPD) An EPD provides consistent and comparable information to industrial customers end-use consumers regarding environmental impacts. Product category rules define how information is to be collected and how measurements are to be made. Environmental Product Declarations Backed up by LCAs. Disclose quantified life cycle data for the product. Must clearly state the life cycle stages and product components covered. Commissioning i i Organization for Implementation Product Category Data Collection Rules Life Cycle Analysis EPD Verification Publication

18 Environmental Performance Base Case (No stain) Product Description Typical board size: ¾ x 6 (31.75mm x 152.4mm) Grade: Average Product composition (on the basis of m 2 of installed decking with a 25-year service life): - Western red cedar lumber: 8.14kg (od basis)/(0.0247m 3 ) - Optional coating stain 1.25 litres - Fasteners (2 ½ galvanized nails, No. 8 or 10): 1kg/m 2 installed decking. Installed and used according to Western Red Cedar Lumber Association specifications (see Base case is an untreated deck. An alternative scenario has regular applications of a stain coating. Impact Category Unit Per m 2 of decking Per 100 ft 2 of decking Total primary energy: Mj Non-renewable, fossil Mj Non-renewable nuclear Mj Renewable (SWHG)* Mj Renewable, biomass Mj Feedstock, non-renewable fossil Mj Feedstock, renewable biomass Mj Renewable material consumption (wood) kg Non-renewable material consumpt. (nails) kg Fresh water use L Total waste Kg Hazardous Kg Non-hazardous kg Global warmingp potential (GWP) Kg CO 2 eq Acidification potential H+ moles eq Eutrophication potential Kg N eq 2.62E E-02 Smog potential Kg NO x eq 5.91E E-01 Ozone depletion potential Kg CFC-11eq 2.55E E-08 * WWHG: Solar, wind, hydroelectric, and geothermal. Environmental Performance, Decking with Regular Applications of Stain Impact Category Unit Per m 2 of decking Per 100 ft 2 of decking Total primary energy: Mj Non-renewable, fossil Mj Non-renewable nuclear Mj Renewable (SWHG)* Mj Renewable, biomass Mj Feedstock, non-renewable fossil Mj Feedstock, renewable biomass Mj Renewable material consumption (wood) kg Non-renewable material consumpt. (nails) kg Fresh water use L Total waste Kg Hazardous Kg Non-hazardous kg Global warming potential (GWP) Kg CO 2 eq Acidification potential H+ moles eq Eutrophication potential Kg N eq 2.62E E-02 Smog potential Kg NO x eq 5.91E E-01 Ozone depletion potential Kg CFC-11eq 2.55E E-08 * WWHG: Solar, wind, hydroelectric, and geothermal. Carbon Balance per 100 ft 2 of Cedar Decking Kg CO 2 eq Alternative Scenario Base Case No Stain Regular Applications of Stain Forest carbon uptake GWP* harvesting and manufacturing Net carbon balance cradle-to-gate GWP transportation to consumer Net carbon balance cradle-to-site GWP installation and use Net carbon balance cradle to end-of-use GWP end-of-life processes Net carbon balance cradle-to-grave * GWP Global warming potential; includes all biogenic carbon sinks and sources throughout the product system boundary.

19 Summary Summary LCA is the only way to determine environmental preferability. LCA is increasingly moving into the mainstream and into code. Systematic assessment consistently shows that production and use of wood products results in lower energy consumption and CO 2 emissions, and lower overall environmental impacts than functionally equivalent non-wood products. Care is needed when selecting an LCA tool or interpreting ti articles about LCA in the media. Summary Environmental product declarations provide valuable, standardized, verified LCA-based information about environmental attributes of products.

20 Questions? This concludes The American Institute of Architects Continuing Education Systems Course Wood Products Council Dovetail Partners