Since February 2009, site based Display Energy Certificates (DECs) and Recommendation Reports no longer meet the requirements of the legislation.  All qualifying buildings on a site must now have their own Display Energy Certificate and Recommendation Report.  Therefore site-based DECs no longer serve a useful purpose and are not issued.
Site owners should be in the process of upgrading metering provision to ensure that the energy consumption of multiple buildings can be separately measured.  Where this has not yet been completed, the government currently allow a DEC assessment to be completed using disaggregated site data.  This is a process where the energy assessor can split the total energy consumption of the whole site up between all the buildings on it.  However, this is often a complex process where it applies and involves significant additional work for the assessor.  For the client, it also means that the information they will receive from the assessment will be less useful and any smaller buildings that would not require their own DEC and Recommendation Report will still need to be surveyed.