Limit values in LCA-based regulations for buildings – System boundaries and implications on practice
Zoé Barjot, Tove Malmqvist
Abstract
Rapidly reducing the climate impacts of the construction and use of buildings is acknowledged as a key lever to meet European and national climate goals. Life cycle-based regulations, in the form of mandatory declaration of the climate impact of new-build, are being introduced, often planned to be or already complemented with performance-based limit values. This development has increasingly raised questions on how different system boundaries for similar limit values applied in various countries might lead to diverging implications in practice. A sample of 50 real-life case buildings of different typologies, representative of contemporary Swedish construction, is used to compare implications of two different system boundaries for embodied GHGe assessment: SB1) life cycle modules A1-A5 i.e. initial, that is upfront GHGe and SB2) life cycle modules A1-A5 + B2-B4, i.e. adding recurring GHGe, according to the European EN 15978 standard. The results show that for the two system boundaries applied, no difference is seen concerning the sample buildings´ ability to perform below a limit value as defined in current Swedish regulatory plans, nor would it lead to different design choices to ensure that a building performs below the limit value. The results of sensitivity analyses along with the relative nature of the results, suggest these conclusions are also relevant for other regulatory contexts. As a conclusion, this study shows that implementing LCA-based regulations focusing on initial embodied GHGe is an important step to rapidly and effectively address GHGe associated with new-build.