Towards life cycle assessment of technical building services in early design phases using building information modelling

Abstract

In order to reach the goal of a net-zero carbon society, the construction industry plays a significant role. Optimising the performance of new buildings in early design phases requires the analysis and evaluation of environmental impacts by life cycle assessment (LCA). The semantic building model can be employed to automatically derive necessary information for LCA to reduce the manual calculation effort. Existing approaches using Building Information Modelling (BIM) for LCA mainly take the operational and the embodied impacts of the building construction materials into account. Still, they do not consider technical building services (TBS), especially in early design phases. However, the embodied carbon of TBS has a significant impact (up to 30% for office buildings) on the whole building LCA and is generally underestimated. Usually, it is considered as a factor of the total LCA but rarely calculated in detail. To identify the research gap, this paper first presents a literature review on existing approaches of the research field of BIM-based LCA of building services. There are just a few approaches in this field, and none of the BIM-based ones are applied in early design phases. The literature review classifies publications in different aspects, such as design phase, TBS Scope, LCA scope, and BIM integration. In a second step, a new methodology focusing on early design phases is presented. As in early design phases, we assume not to have a TBS model yet, an energy demand analysis and pre-dimensioning of TBS components are included in the methodology. Afterwards, LCA is calculated for the main TBS components based on the quantity take-off of the pre-dimensioned components.