Impact of building service life models on life cycle assessment

Life cycle assessments (LCAs) of buildings often use an operational lifetime of approximately 50 years, and have simplified descriptions of building operations and maintenance. The typical service life period is inappropriate for some materials given their exposure and use, and the simplified descriptions do not fully represent maintenance, repair and replacement cycles. Building service life prediction modelling is examined to improve the representation of service life in LCA and the evaluation of environmental impacts. A process is developed that incorporates service life, operational energy and LCA modelling which provides a means of examining the effects of materials and systems in building operation, maintenance, repair and replacement. This process advances the field of building LCA by representing a more complete and accurate building life cycle, and by highlighting the impact of building service life models on the LCA methodological assumptions. Nine building envelope combinations are modelled. Cumulative life cycle impact and life cycle impact per year are shown to be primarily dependent on predicted material longevity (i.e. the frequency of major replacement of the envelope systems, as well as the differences in the frequency and intensity of prescribed maintenance) and the environmental indicators analysed.