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Certificate study

A CIBSE study has found that the benchmark figures used in Display Energy Certificates are fit-for-purpose, with 94% of buildings included in the study showing a good correlation between the benchmarks and the actual operational ratings.

CIBSE has published the results of a study of the first 45,000 DECs lodged on the Landmark register from October 2008 to mid-February 2010. The study focused on Operational Ratings, to assess the applicability of the CIBSE Benchmarks and to recommend to the Department of Communities and Local Government any immediate changes needed to the benchmarks or allowances.


UCL Energy Institute, worked with Robert Cohen of Camco and Bill Bordass of the Usable Buildings Trust to undertake a detailed review of the data contained in the DEC database. The results show that the benchmarking system works well for those building categories most commonly found in the database; 15,335 are schools, accounting for 52% of buildings with DECs, and the median school DEC Grade is within 2% of the benchmark. For offices with 3,230 buildings or 11% of the total, the median is almost exactly at the D/E boundary where it should be.

The benchmarks also work well for clinics, hospitals and emergency service buildings.

The benchmarks for entertainment halls and theatres, dry sports and leisure facilities appear to be too generous. Benchmarks for laboratories and operating theatres and for workshops need some further review, in particular of their special energy uses, where electrical equipment has high loads and may need to be added to the list of separable uses.

The evidence available from this analysis of DEC data and benchmarks allowed the CIBSE benchmarks group to make a valuable contribution to the UK-GBC report on the wider roll out of DECs to the private sector to promote energy efficiency in non-domestic buildings.

To see the CIBSE report click here