Widening understanding of low embodied impact buildings: Results and recommendations from 80 multi-national quantitative and qualitative case studies

This paper publishes the results from a major five year International Energy Agency research project which investigated the reduction of embodied energy and greenhouse gas emissions over the whole life (‘cradle to grave’) of buildings. Annex 57 collated and analysed over 80 detailed quantitative and qualitative building case studies from the participating nations. For many years the multiple variations in methodological approach of case studies to assess the whole life embodied impacts of buildings have presented a major challenge for politicians and other decision makers. Any real change in design and construction practice has also proved elusive. This paper describes a modified research synthesis and meta analysis as a novel and valid method for drawing meaningful conclusions from large sets of significantly diverse studies. The quantitative analyses consider embodied impacts of the product stage, replacement, and end of life stages, of new and refurbished buildings, and of different building assemblies and construction materials. The product stage is shown to dominate in most cases, with the median value around two thirds of the whole life embodied impacts, with replacements the next highest with a median figure of around 25%; however replacements in five studies were over 50% of the whole life impacts. It should be noted that several life cycle stages are still missing from these studies. The case studies included eleven refurbishment projects, in which energy efficient measures and low carbon technologies were retrofitted to existing buildings; for these projects the median product stage impact was found to be just under half that for the new build projects. While further research is required to compare the operational energy use in the new and refurbished buildings, this suggests that such energy refurbishments have a significantly lower impact than new buildings. Several other studies considered the impacts from technical equipment and internal fixtures and fittings, both frequently excluded, and demonstrated that they can be responsible for up to 45% of the whole life embodied greenhouse gases and up to 48% of the whole life embodied energy. Finally, the paper combines the analysis of the quantitative case studies with that of qualitative studies, to explore the impact of contextual factors at both policy and project level in significantly reducing the embodied environmental impacts of buildings. The case studies have shown that planning authorities, major clients, developers, and individual designers, can all play an important role in reducing embodied impacts through encouraging innovation. The paper concludes with recommendations for policy makers, designers and LCA modelers which will support and effect real reductions in the whole life embodied impacts of buildings.