Life-cycle cost analysis of retrofit scenarios for a UK residential dwelling

Abstract

The UK government is committed to reducing carbon dioxide emission levels by 80%, comparative to the 1990 baseline, by 2050. ‘Nearly-zero-energy buildings’ (nZEBs) were introduced by the Energy Performance Building Directive (recast) in 2010 as a realistic solution to the intrinsic environmental debt associated with most existing buildings. This paper aims to carry out a life-cycle cost (LCC) analysis to identify what is a cost-optimal level and how best to achieve this by examining and focusing on the exploration of realistically applicable energy-efficient measures and retrofit scenarios for a typical UK dwelling. A sensitivity analysis is used to identify uncertainty and provide the expected economic benefits and losses of the applied scenarios over their respective lifetimes. It was established that the total LCCs of all the retrofit scenarios were in fact lower than that of the baseline scenario (i.e. not retrofitting the property) over the 30-year study period. Furthermore, it was found that the cost-optimal level for the retrofit of a typical UK residential dwelling is 75 (kWh/m 2 )/year; meanwhile, the UK’s current nZEB target stands at 44 (kWh/m 2 )/year, meaning that there is a gap between the current nZEB target and the calculated cost-optimal level.