Review of Energy Benchmarks for Display Energy Certificates

CIBSE Technical Symposium, DeMontfort University, Leicester UK
6th and 7th September 2011

Display Energy Certificates (DECs) were introduced in summer 2008 under the Energy Performance of Buildings Directive Regulations. By mid February 2010 some 45,000 DECs had been lodged on the central Landmark database which offers a wealth of feedback on the performance of the non-domestic public sector building stock. It also provides a view on how well the DEC process is working and whether the energy benchmarks in CIBSE TM46 that underpin the process are sound. This paper reviews the TM46 benchmarks using analysis of the 45,000 DEC records lodged in the central register database by mid-February 2010.
The study found that 94% of buildings in the database are in benchmark categories for which the median rating is within one grade of the TM46 benchmark. The median for offices is almost exactly at the benchmark level and the median for schools is within 2% of the TM46 benchmark. However, there are some data quality and categorisation problems in the DEC database and it reveals evidence of widespread non-compliance. In many sectors there is a marked trend of higher electricity and lower heating consumption than the TM46 energy benchmarks anticipated, although this often cancels out for overall CO2 so that medians end up close to the benchmark.