Embodied Carbon Research Project

Transcription

1 Embodied Carbon Research Project Charles Sturt University Gregory Keppie 2013

2 Introduction The goal of this report is to quantify the amount of embodied carbon in two recently completed buildings located on the grounds of Charles Sturt University (CSU) Albury and CSU Wagga Wagga (Figures 1 & 2), and a yet to be constructed building located at CSU Wagga Wagga. The embodied carbon results relate to the carbon emissions created by the material from cradle to gate, the processes involved in the extraction, manufacture and delivery of building materials (Figure 3) to the construction site (Hammond & Jones, 2008). The three buildings have been designed for different purposes, one building is used for lectures and administration, another building provides accommodation for students whilst the third building will be used as an early learning centre. Figure 1 Academic office accommodation, CSU Albury Figure 2 Student accommodation, CSU Wagga Wagga. 2

3 Diesel Aggregate production Limestone/clay production Explosives Rock quarrying Limestone mining Electricity Crushing Crushing Water Screening Blending Coal, gas other thermal fuels Fine aggregate Course aggregate Cement production Raw mill Transport Preheater/ recalciner Rotary kiln Cooler Cement mill Concrete production Silos/ dispatching Weighing hoppers Transport Mixing Transport Concrete Mortar Render Figure 3. An example of the processes involved in the creation of the cement and aggregate used for concrete, render and mortar from cradle to gate (Building Products Innovation Council, 2010) 3

4 For the purpose of this report, only the materials which contribute to the finished building shell have been calculated for their embodied carbon rate. The building shell includes materials such as internal floor and wall finishes, ceiling linings, insulation as well as materials such as steel and concrete. Each construction material has a different embodied carbon rate (Appendix A). Available embodied carbon rates for the materials used in the construction of the three buildings allowed the calculation of the total emission produced for each material (Appendix B, C & D). Many of the materials used for construction are the same in all three buildings. There are however, several areas where different materials have been used for a similar function on each of the buildings. The academic office accommodation has been built with the intention of using materials with a lower embodied carbon rate as a substitute for similar materials which have a higher embodied carbon rate. The concrete which has been used on this building has had the cement input of the concrete reduced to 80% of what is the standard ratio of cement input (Cement & Concrete Aggregates Australia, 2004) and 20% of the aggregate will be recycled material. The 20% gap caused by the removal of cement has been replaced with fly-ash a byproduct of coal fired power stations (French & Smitham, 2007). The fly-ash has been sourced from a coal fired power station located in South East Queensland. As this product is a waste product which has had its embodied carbon released during processing, it is not considered to possess any embodied carbon however there is an embodied carbon rate applicable to the removal from the power station and transportation to the concrete batching plant. The steel which has been used for reinforcement in all in-situ concrete for the academic office accommodation will be made from 100% recycled material. There were no available rates of carbon dioxide (CO₂), for steel which is entirely made from recycled material so the rate for steel containing a recycled material content of 42% was used. The concrete and steel reinforcement for the academic accommodation are the two materials which have a significantly lower embodied carbon rate than the similar materials used in the other two buildings. 4

5 Method A desktop search for embodied carbon rates was conducted for relevant building materials used in the construction of the new academic office accommodation building (stage 3), the CSU residential accommodation and a yet to be constructed early learning centre. Where possible, embodied carbon rates based on Australian materials and processes has been used. In instances where no Australian data relevant to the material was available, rates of embodied carbon from sources based in the UK was used. The predominant source of rates of embodied carbon in materials is the UK based program SimaPro. Other sources for embodied carbon rates have been Forest and Wood Products Australia, greenspec, Inventory of Carbon & Energy (ICE). Quantities of construction materials were taken from the available plans and specifications for the buildings selected. There were no complete plans or specifications for the buildings selected for the research however tender documents provided much of the data needed for the academic accommodation building and the early learning centre. The student accommodation building required several days of measuring plans to scale and matching sections of the elevations to details contained in the available plans. A field trip was undertaken to take measurements off the completed building where there was not enough detail contained in the available plans. Where data available to calculate quantities of a material was limited the quantity was assumed based on material quantity rates contained in Australian Standards. The embodied carbon rate relevant to each construction material was applied and a total embodied carbon rate was calculated. The data was then used to create a table in excel (Appendix B). The total embodied carbon for each of the buildings was divided by the floor area to give a rate of kilograms of embodied carbon per square metre of floor area. The embodied carbon rate for each building was then able to be compared against each other. 5

6 The final calculations of the three buildings have shown a significant difference in the Results amount of embodied carbon per square metre of floor (Table 1). The academic office accommodation building has the lowest amount of embodied carbon per square metre of floor area out of the three buildings (Table 1). The area where the biggest difference of CO₂ per square metre between all three buildings was in the floor structure. The floor structure used similar materials in all three buildings. The use of recycled materials for both steel reinforcement and concrete has resulted in a significant reduction of CO ₂ for the academic office accommodation with both the early learning centre and the student accommodation having an embodied carbon rate of 481 kilograms of embodied carbon per square metre (kgco₂/m²) and the academic accommodation having a rate of 271 (kgco₂/m²), (Appendix B & C). Table 1. Kilograms of embodied carbon per square metre of floor area Building Total floor area Total embodied Kg Co₂/m² (m²) carbon (kg) Student accommodation building Academic office accommodation Early Learning Centre The materials used in the wall structure differ between the three structures. The wall structure of the academic and student accommodation is predominately pre-cast concrete paneling whilst the early learning centre is a lined steel frame. The volume of materials (figure 5), shows the early learning centre to have a significantly smaller volume of materials despite being much larger than the student accommodation building. The total volume of embodied CO₂ (figure 6), 6

7 is lower in the early learning centre whilst both the student and academic accommodation have a similar volume of CO₂. The amount of CO₂ per metre square of wall structure (table 2) is lowest in the early learning centre whilst there is a significant reduction in embodied carbon in the academic accommodation when compared to the student accommodation. Figure 5. Total volume of materials used in each building (Appendix B). Figure 6. Total quantity of embodied carbon in the combined wall structure materials of each building (Appendix B). 7

8 Table 2 Kilograms of embodied carbon per square metre of the wall structure. Building Student accommodation Academic accommodation Early learning centre Kg Co₂/m² Discussion As can be seen from the results in table 1, the academic office accommodation has the lowest rate of embodied carbon per square metre of all three buildings. It has been built with the aim to reduce the embodied carbon of the building materials used in its structure whilst the other two structures have not. Of these two structures, the residential accommodation has a similar structure to the academic accommodation whilst the early learning centre is a more lightweight structure. The early learning centre does not have any pre-cast concrete paneling for its walls which is not the case for the academic office accommodation or the residential accommodation. 80% of the walls in the early learning centre have been constructed with a steel frame which is lined externally with zincalume and internally with plasterboard. The remaining wall area is covered by glazing or timber doors. The lightweight nature of this method of construction has a much lower rate of embodied carbon. The volume of materials used in the early learning centre is significantly lower than either the residential or the academic accommodation which both have large areas of concrete panels. Concrete has a much lower embodied carbon rate (333.6kg/m³) than steel (12207kg/m³) but the volume of concrete per square metre of precast paneling is much greater than that of the volume of materials used in the lined steel frame (figure 5). Despite the lightweight structure of the childcare centre, it still has a total embodied carbon per square metre greater than that of the academic accommodation. 8

9 Further research into operational energy use for cooling and heating needs of each building and temperature variation will allow for comparison between the thermal performance of the construction materials used. 9

10 References Building Products Innovation Council. (2010). Life-Cycle Industry Database. Retrieved from Cement & Concrete Aggregates Australia. (2006). Concrete Basics- A guide to concrete practice. Retrieved from French. D., & Smithham. J. (2007). Fly Ash Characteristics and Feed Coal Properties. Cooperative research centre for coal in sustainable development. Retrieved from Forest & Wood Products Australia. (2010). Development of an Embodied CO₂ Emissions Module for Accurate. Market Access & Development PNA Retrieved from Hammond. G., & Jones. C. (2008). Inventory of Carbon & Energy (ICE). Version 1.6a. University of Bath, UK. Retrieved from 10

11 Appendix A. Rates of embodied carbon for materials used in the construction of the academic office accommodation and the residential accommodation at the CSU Campus, Albury (FWPA, 2010; BPIC, 2010; Hammond & Jones, 2008). Material Unit kgco2/unit Comments Aluminum m³ Cement m³ 307 Cement render (6:1:1) m³ Compressed fibre cement sheet m³ (Villaboard, 9mm sheet) Concrete m³ General concrete 25MPa Concrete m³ less 20% cement, replaced with fly ash Plasterboard m³ Plywood m³ Softwood with carbon sequestration Polyester insulation R3 m³ Polycarbonate m³ Rigid polystyrene m³ 58.7 Zincalume* m³ Aluminum 55%, Zinc 43.5%, Silicon 1.5% Steel (General) m³ Steel (reinforcement) m³ Steel (reinforcement)* m³ % recycled content Steel (Galvanized) m³ Doors m³ Solid hardwood interior, ply veneer. 19kg Windows m² Double glazed anodized aluminium 11

12 frame Windows m² Toughened anodized aluminium fame Carpet + rubber underlay m³ Zinc m³ *The profile of each sheet of colourbond (zincalume) was unavailable so the true length could not be calculated; the area covered in m² was used instead. Appendix B. Quantities and embodied carbon rates for materials used in the academic accommodation. Material Quantity Unit Count EC (Embodied Carbon) kg CO₂/unit Floor structure CO₂-e (kg) Steel reinforcement (mesh and bars) 3.82 m Concrete (floor) m Concrete (footing) m³ Concrete (pre-cast, hollow core panels, 50MPa) m Cement topping to slab m³ Floor structure subtotal Soffit Linning Perforated plywood 2.26 m³ Plasterboard m³ Fibre-cement sheeting m³ Frame structure subtotal

13 Roof structure Roof frame members m Colourbond roofing m Box gutter m Eave gutter m Roof structure subtotal Wall structure Fibre-cement sheeting m Stud wall partition m Awning frame 0.03 m Glazed partition 117 m² Glazed sliding door 77 m² Wall structure subtotal Internal finishes Plasterboard m Aluminium ducted skirting m Interface modular carpet 9.56 m Internal finishes subtotal Misc materials Cement Render (6:1:1) m³ Zincalume flashing m³ Zincalume downpipe m³

14 Zincalume chimney m³ Polyester insulation R m³ Doors(solid core) m³ Aluminium windows 186 m² Internal finishes subtotal Building total Appendix C. Quantities and embodied carbon rates for materials used in the early learning and childcare centre. Material Quantity Unit Count EC (Embodied CO₂-e (kg) Carbon) kg CO₂/unit Floor structure Steel reinforcement (mesh and bars) m Concrete (floor) 149 m Concrete (footing) 47 m³ Floor structure subtotal Soffit Linning Colourbond m³ Plasterboard m³ Fibre-cement sheeting m³ Frame structure subtotal Roof structure Roof frame members 2.1 m Colourbond roofing m Box gutter m

15 Eave gutter m Ridge capping m Colourbond fascia m Roof structure subtotal Wall structure Fibre-cement sheeting 1.71 m Stud wall partition m Colourbond sheeting m Wall structure subtotal Internal finishes Plasterboard m Fibre cement sheeting m Interface modular carpet 4.96 m Vinyl flooring m MDF skirting m Internal finishes subtotal Misc materials Polyester insulation 24.7 m³ Glass fibre insulation m³ Aluminium windows 180 m² Doors(solid core) m³ PVC downpipe 0.06 m³ Internal finishes subtotal Building total

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