A review of the limitations of Life Cycle Energy Analysis for the design of fabric First loW-energy domestic retrofits

Reduction of energy for space heating through retrofit interventions is imperative to meet carbon reduction targets in many temperate climates. A Life Cycle approach to retrofit design has the potential to reveal the balance between projected operational energy savings, and embodied energy invested in an intervention, and therefore optimise the extent of retrofit. However, life cycle energy analysis (LCEA) suffers from inconsistent methodologies across studies, and is rarely used for retrofit projects. A preliminary meta-analysis was conducted, drawing on LCEA data from domestic new builds and retrofits from the last twenty years. Whilst recent literature conversations indicate that embodied energy increases with decreasing operating energy, the meta-analysis is inconsistent with this. This review critiques the limitations and sources of variation in LCEA, focuses on how these compromise its value as part of the building design process and when comparing between projects, and recommends approaches which add value for building designers. This review has identified a need for research to elucidate a transferrable approach for determining the lowest life cycle energy for any retrofit, and also a need for a more robust data set of domestic retrofit LCEA.