Investigation of load-bearing structures and other influencing factors within the framework of building LCA by example of German residential buildings

Abstract

The environmental assessment of buildings is becoming increasingly important in the context of decarbonisation of the construction sector. The aim of this study is to investigate the influence of the load-bearing structure on the total embodied environmental impacts of multi-family houses and the effects of different versions of the ÖKOBAUDAT database on life cycle assessment for the context of Germany. The analysis is based on three case study multi-family houses, each represented by three equivalent construction types (nine building variants in total), using the functional unit of 1 m2 gross floor area (GFA) over a 50-year reference study period. Given the case-study-based approach, the extent to which the findings can be transferred to other geographic contexts and building types remains to be investigated. The life cycle assessment includes the embodied life cycle modules A1–A3, B4, and C3–C4. The central environmental indicators Global Warming Potential (GWP), non-renewable primary energy (PENRE) and renewable primary energy (PERE) are examined. The results show that the load-bearing structure accounts for around two-thirds of the total environmental impact of a building and is therefore a key lever for decarbonisation strategies. Wooden buildings emit significantly less greenhouse gases and consume less non-renewable primary energy than their mineral pendants. Non-load-bearing building elements, which account for around one-third of the environmental impact, also offer further potential for reduction. Furthermore, a comparison of LCA results from three versions of the ÖKOBAUDAT database shows that the environmental indicators examined tend to increase with newer database versions, while national primary energy consumption decreases overall. About two thirds of embodied whole building environmental impacts are induced by the load-bearing structure. Load-bearing structure’s influence on whole building embodied environmental impacts is about equal for wood and mineral buildings. Environmental impacts of mineral buildings are higher than their wood pendants. Embodied whole building environmental impacts increase with more recent LCA database version. Energy intensity of buildings is increasing, while national energy consumption decreases.