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Life cycle assessment of buildings

Author(s): N. Kohler
Paper category: symposium
Book title: International Symposium on Life Cycle Assessment and Construction – Civil engineering and buildings
Editor(s): A. Ventura and C. de la Roche
Print ISBN: 978-2-35158-127-8
e-ISBN: 978-2-35158-128-5
Publisher: RILEM Publications SARL
Pages: 14 - 16
Total Pages: 3
Language: English

Abstract: The origins of the Life Cycle Assessment (LCA) methodology are in the 1970-ies and LCA became an ISO standard in 1997. First applications to buildings were made in the 1980-ties and in 1995 a first EU program defined LCA for buildings. The parallel discussion on sustainability and climate change has confirmed the explicit needs for building LCA. In the last decade basic inventory data became publically available and commercial LCA software appeared. A success story then? Except that 30 years later there are still no large-scale applications, no systematic comparative analysis based on a significant number of buildings, no common benchmarks, no uncertainty consideration. There seems to be a curious gap between dynamic research and the development of new methods and a lack of application.
The basic conditions for the application, i.e. objectives, system limits, functional units indicators were rapidly defined and no more questioned until recently. The reasons for the lacking application are probably not due to methodological problems of LCA but to an insufficient awareness of the complexity of buildings and their use: buildings cannot be separated from their economic, social and cultural context. LCA generally considers buildings as objects neglecting the fact that buildings can also be considered as a service. In this case functional units change profoundly, the time of occupation, the number of persons per surface, the interior climate etc. change. System limits, use assumptions, functional units influence LCA results much more than the generally considered construction materials, insulation thickness or boiler efficiency. The long lifetime of buildings distinguishes them from manufactured objects. Survival curves of existing buildings show half-life times of centuries and not decades (at least in European cities). But if buildings remain with the same volume and at the same geographic location, their interior and exterior changes several times during their life span. In fact one should maybe consider buildings not as one building but as several consecutive buildings. “Buildings learn” (Steward Brand) or change identity. LCA results can only be validated for the very beginning of the building life span (in most cases the time of the design and construction). The largest part of the building life is highly uncertain and the detailed rules of the life cycle scenarios, necessary to obtain comparable results, hide the fact that we don’t know what will happen to a changing building under changing circumstances.

Online publication: 2012
Publication Type: full_text
Public price (Euros): 0.00

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