The relevance of the building system boundary to conduct an LCA of a passive house: A comparison of two frameworks for assessing building sustainable performance DGNB and Level(s)

Session
WE.1.A || Life Cycle Sustainability in Construction and Renovation of Buildings

Authors
Soust-Verdaguer, Bernardette; Palumbo, Elisabetta; Llatas, Carmen; Traverso, Marzia

Abstract
Current decarbonization and climate change mitigation scenarios are moving us towards defining strategies to reduce the environmental impacts produced by the built environment. Various authors have shown that the different strategies focused on the reduction of operational impacts can increase the embodied impacts related to the building materials, so resulting in no overall improvement in its environmental performance. Thus, the balance between operational and embodied impacts is attracting increased attention in research. The literature demonstrates a greater use of Life Cycle Assessment (LCA) to give guarantees regarding the embodied impacts assessment. Hence, it becomes essential to evaluate building performance from a broader LCA perspective, namely from as full a system boundary as possible. To support architects and engineers in to use of LCA and to overcome the complexity of calculations in design stage practice, different building sustainability performance assessments propose to include a simplified LCA method. Nevertheless, the implementation of LCA in these sustainability assessment frameworks is not completely harmonised, causing problems of inaccuracy and incomplete assessments that generate incomparability among case studies and even possible deviations to achieve carbon- neutral scenarios. Thus, a system boundary definition is a key step. The present paper aims to analyse LCA implementation in a building envelope of a certified Passive house located in Italy. Two building sustainability frameworks (DGNB and Level(s)) are used to identify how the system boundary definition influences the impact assessment results. The study keeps the LCA methodological assumptions (data sources, impact categories, characterisation methods and indicators) constant to allow a comparison focused on the system boundary implications (such as the modularity principle of LCA). Results show the margins and reduction percentages that can be achieved by the two different assessment frameworks. Finally, the limitations and challenges related to the methodological aspects in the use of simplified LCA to calculate the impacts of a Passive House building are addressed.