Abstract
Energy Performance Certificates (EPCs) are designed to provide consistent and comparable energy efficiency ratings. Since 2008, any building constructed, rented or sold is required to obtain an EPC in the UK. 4% of simple office buildings have renewed their EPC to date in England and Wales. In this paper, by comparing the original and renewed EPCs of these buildings, we examine the reliability of non-domestic EPC ratings and discover realistic energy efficiency improvement strategies reflected in the changes. We have found that buildings with their conditions remaining unchanged can be better rated by approximately 10 points on average when their initial rating is above the minimum requirement in the regulation. The ones initially rated below the minimum requirement are expected to have a greater scale of improvement on ratings while making no efforts which brings doubts on the effect of the “Minimum Energy Efficiency Standard” policy. Evidenced human factors are also jeopardising the fairness of EPC ratings. Based on the changes in the EPCs, we have found 4 clusters of improved buildings and 5 clusters of deteriorated buildings. We derived practical energy efficiency improvement strategies that people have already naturally adopted.
•Analysis of EPC renewal of the same buildings shows the unreliability of EPC ratings.•The Minimum Energy Efficiency Standards policy is cast in doubt.•Buildings with bad initial Asset Ratings are found easier to improve and vice versa.•Cluster analysis and Association Rule Mining found renewal patterns in EPCs.•Patterns of EPC recommendation changes show viable pragmatic retrofit options.