Abstract
In the face of the unfolding climate crisis, the role and importance of reducing Greenhouse gas (GHG) emissions from the building sector is increasing. This study investigates the global trends of GHG emissions occurring across the life cycle of buildings by systematically compiling life cycle assessment (LCA) studies and analysing more than 650 building cases. Based on the data extracted from these LCA studies, the influence of features related to LCA methodology and building design is analysed. Results show that embodied GHG emissions, which mainly arise from manufacturing and processing of building materials, are dominating life cycle emissions of new, advanced buildings. Analysis of GHG emissions at the time of occurrence, shows the upfront ‘carbon spike’ and emphasises the need to address and reduce the GHG ‘investment’ for new buildings. Comparing the results with existing life cycle-related benchmarks, we find only a small number of cases meeting the benchmark. Critically reflecting on the benchmark comparison, an in-depth analysis reveals different reasons for cases achieving the benchmark. While one would expect that different building design strategies and material choices lead to high or low embodied GHG emissions, the results mainly correlate with decisions related to LCA methodology, i.e. the scope of the assessments. The results emphasize the strong need for transparency in the reporting of LCA studies as well as need for consistency when applying environmental benchmarks. Furthermore, the paper opens up the discussion on the potential of utilizing big data and machine learning for analysis and prediction of environmental performance of buildings.
Highlights
The paper builds on a recently published meta-analysis investigating more than 650 building life cycle assessment (LCA) studies by elaborating on the benchmark comparison using Swiss SIA 2040 life cycle-related benchmarks, as well as by conducting additional in-depth data extraction and analysis on the ‘best cases’
The results show that the reporting of relevant features of building LCA studies is a big problem and that there is a need for clear guidelines on transparency standards and minimum documentation requirements to ensure quality and reproducibility of building LCA studies
The analysis of the limited amount of cases showed that features related to methodological decisions, by example of building parts included and life cycle stages covered in the study, have more influence on the results than building’s structural system and main construction material
Summary
Climate change is real and the fight to limit global warming and avoid ecosystem collapse are considered the major challenges of our time [1]. The global efforts to limit climate change require strong contributions from all sectors, with a special role for buildings and construction. In the latter sectors, this leads to a new approach in setting benchmarks and specific design goals. There were various design goals and legal requirements for different types of buildings, in specific climatic zones, and adapted to political, cultural and other circumstances, the new target is a common one globally: to construct and operate buildings that no longer (or only to a necessary minimum) contribute to further GHG emissions
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