Embodied carbon and building retrofit: A heritage example

There is a critical need to reduce energy and associated carbon emissions from the existing built environment to help mitigate climate change. This requires significant upscaling of energy retrofitting. However, at present, retrofit assessments commonly consider only the operational impacts, neglecting the embodied carbon of measures. If retrofits are to make the greatest lifecycle savings, this embodied carbon should clearly be included. This chapter assesses the embodied carbon of 40 retrofit measures, chosen as options to retrofit 13 residential heritage buildings in northern England. The assumptions and decisions made in the assessment process and the suitability of the international lifecycle assessment (LCA) standard EN 15978 – designed primarily for new construction – for heritage retrofit are discussed. The contribution of the different lifecycle stages is assessed, and the total embodied carbon of the different measures is identified. Embodied carbon costs varied significantly across the different measures and material options, while in many cases offering similar operational carbon savings. In some cases, lifecycle stages which are often deemed insignificant were found to have a substantial impact on total embodied carbon. The study also identified a lack of available LCA data for some measures and noted a number of areas where EN 15978 was challenging to apply for retrofit projects. These findings emphasise the importance of assessing embodied carbon for energy retrofitting, including as many lifecycle stages in the assessment as possible, and increasing the availability of LCA data for retrofit measures. Greater attention to this issue is needed to maximise lifecycle savings from the retrofit of existing buildings and thus help to mitigate climate change