Life cycle assessment of construction materials: the influence of assumptions in end-of-life modelling
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The nature of end-of-life (EoL) processes is highly uncertain for constructions built today. This uncertainty is often neglected in life cycle assessments (LCAs) of construction materials. This paper tests how EoL assumptions influence LCA comparisons of two alternative roof construction elements: glue-laminated wooden beams and steel frames. The assumptions tested include the type of technology and the use of attributional or consequential modelling approaches.
The study covers impact categories often considered in the construction industry: total and non-renewable primary energy demand, water depletion, global warming, eutrophication and photo-chemical oxidant creation. The following elements of the EoL processes are tested: energy source used in demolition, fuel type used for transportation to the disposal site, means of disposal and method for handling allocation problems of the EoL modelling. Two assumptions regarding technology development are tested: no development from today’s technologies and that today’s low-impact technologies have become representative for the average future technologies. For allocating environmental impacts of the waste handling to by-products (heat or recycled material), an attributional cut-off approach is compared with a consequential substitution approach. A scenario excluding all EoL processes is also considered.
Results and discussion
In all comparable scenarios, glulam beams have clear environmental benefits compared to steel frames, except for in a scenario in which steel frames are recycled and today’s average steel production is substituted, in which impacts are similar. The choice of methodological approach (attributional, consequential or fully disregarding EoL processes) does not seem to influence the relative performance of the compared construction elements. In absolute terms, four factors are shown to be critical for the results: whether EoL phases are considered at all, whether recycling or incineration is assumed in the disposal of glulam beams, whether a consequential or attributional approach is used in modelling the disposal processes and whether today’s average technology or a low-impact technology is assumed for the substituted technology.
The results suggest that EoL assumptions can be highly important for LCA comparisons of construction materials, particularly in absolute terms. Therefore, we recommend that EoL uncertainties are taken into consideration in any LCA of long-lived products. For the studied product type, LCA practitioners should particularly consider EoL assumptions regarding the means of disposal, the expected technology development of disposal processes and any substituted technology and the choice between attributional and consequential approaches.
KeywordsAttributional Consequential Construction product Disposal LCA Long-lived product Infrastructure Waste management
This research was funded by the EU FP7 grant 246434, WoodLife.
- Björklund T, Tillman A-M (1997) LCA of Building Frame Structures: Environmental Impact over the Life Cycle of Wooden and Concrete Frames. Technical Environmental Planning Report 1997:2, Chalmers University of Technology, Gothenburg, SwedenGoogle Scholar
- Björklund T, Jönsson Å, Tillman A-M (1996) LCA of Building Frame Structures: Environmental Impact over the Life Cycle of Concrete and Steel Frames. Technical Environmental Planning Report 1996:8, Chalmers University of Technology, Gothenburg, SwedenGoogle Scholar
- Börjesson L, Höjer M, Dreborg K-H, Ekvall T, Finnveden G (2005) Towards a user’s guide to scenarios—a report on scenario types and scenario techniques. Environmental Strategies Research, Department of Urban Studies, Royal Institute of Technology, StockholmGoogle Scholar
- BSI (2011) PAS 2050:11, Specification for the Assessment of the Life Cycle Greenhouse Gas Emissions of Goods and Services. http://shop.bsigroup.com/en/forms/PASs/PAS-2050. Accessed 18 February 2013
- Carling O (2008) Limträ: handbok (English: “Glulam: handbook”). Print and Media Center i Sundsvall AB, Sundsvall, Sweden. http://www.svensktlimtra.se/Upload/File/publikationer/2009/Limtrahandbok_200812.pdf. Accessed 7 March 2012
- Erlandsson M (2007) Miljödeklaration: limträ (English: “Environmental product declaration: glulam”). http://www.svensktlimtra.se/Upload/File/publikationer/Limtra_miljovarudeklaration%20.pdf. Accessed 6 February 2013
- European Commission (2010) International Reference Life Cycle Data System (ILCD) Handbook—general guide for life cycle assessment—detailed guidance, 1st edn. Publications Office of the European Union, LuxembourgGoogle Scholar
- Goedkoop M, Heijungs R, Huijbregts M, De Schryver A, Struijs J, Van Zelm R (2012) ReCiPe 2008 (first edition) – report I: characterisation (updated 13 July 2012). http://www.lcia-recipe.net. Accessed January 21 2013
- Guinée JB, Gorrée M, Heijungs R, Huppes G, Kleijn R, Koning A et al (2002) Handbook on life cycle assessment. Kluwer, DordrechtGoogle Scholar
- Jungbluth N, Emmenegger MF, Dinkel F, Stettler C, Gabor D, Chudacoff M et al (2007) Life Cycle Inventories of Bioenergy. Ecoinvent report no. 17. Swiss Centre for Life Cycle Inventories, DübendorfGoogle Scholar
- Lippke B, Wilson J, Meil J, Taylor A (2010) Characterising the impact of carbon stored in wood products. Wood Fiber Sci 42:5–14Google Scholar
- PE International (2013) GaBi software. http://www.gabi-software.com
- Puettmann M, Olein E, Johnson L (2013) Cradle to gate life cycle assessment of glue-laminated timbers production from the Pacific Northwest. http://www.corrim.org/pubs/reports/2013/phase1_updates/PNW%20Glulam%20LCA%20report%201_7_13%20final.pdf. Accessed 6 February 2013
- Schmidt J H, Merciai S, Thrane M, Dalgaard R (2011) Inventory of country specific electricity in LCA – Consequential and attributional scenarios, Methodology report. 2.−0 LCA consultants. www.lca-net.com/projects/electricity_in_lca. Accessed 5 October 2012
- SIS (2012) SS-EN 15804:2012 Sustainability of construction works—environmental product declarations—core roles for the product category of construction products. Swedish Standards Institute, StockholmGoogle Scholar
- WBCSD/WRI (2011) Product Accounting & Reporting Standard. www.ghgprotocol.org/files/ghgp/Product%20Life%20Cycle%20Accounting%20and%20Reporting%20Standard.pdf. Accessed 18 February 2013