ENERGY DO DECS ADD UP? E
xisting buildings in both the private and public sector consume significant amounts of energy. Although there are plenty of new build projects designed to be energy efficient, the UK’s existing stock of buildings are going to be occupied for many years to come. Even in a construction boom we only replace one per cent of our building stock every year, which means eighty seven per cent of buildings that will be around in 2050 have already been built. That means the pressure to reduce energy consumption in all buildings can only grow, particularly in refurbishment. In itself this will put pressure on building operators to improve their understanding of how they are using energy, and the scope for reducing waste. This is why the UK now has two forms of mandatory energy performance certification, courtesy of the Energy Performance of Buildings Directive: the Energy Performance Certificate (EPC) and the Display Energy Certificate (DEC).. In 2008 the department for Communities and Local Government (CLG) took the bold step of requiring mandatory DECs for all public buildings over 1000 m2
that were regularly visited
by members of the public. In recent months, Government has been sounding out extending DECs to cover public
Figure 1
Mandatory energy certification aims to give building owners a true picture of their energy consumption. How well is the system working? Andrew Geens and Richard Hillyard investigate.
buildings over 250 m2 that are also
regularly visited by the public. But what are we learning from the Display Energy Certificates issued to date? Is the assessment system working well? Can we tell if building energy efficiency is improving? What needs to be done next? BSRIA has been looking at the statistics behind 28 259 completed DEC assessments made up until November 2009. It is useful to look at this dataset now, as it represents the first year’s DEC assessments conducted and paints an interesting picture of the current situation in building energy management. The dataset was made available through Environmental Information Legislation upon request of the BBC. (Note that Landmark manages and maintains the database from EPC and DECs on behalf of the CLG, and this data is not made publicly available.)
A DEC is designed to give an
Operational Rating (OR) score of 0 (A) to over 150 (G). A default score has been set at 200 for buildings that have insufficient energy data to complete the assessment. A score of 100 is defined as typical for the building type.
The first thing that stands out is that the database represents 28,259 assessments, not 28,259 different buildings. Some properties have had multiple assessments. It is likely, in a process that is new to everyone, that errors have been discovered after lodgement, and having been corrected, the certificate has been re-lodged. Nevertheless, this large amount of data gives a good insight into the pattern of UK public sector building energy consumption. Figure 1 shows the distribution of the 28,259 assessments against the A to G scale. At the time the DEC system was introduced it was considered that the
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SUSTAINABLE FM | DECEMBER 2010/JANUARY 2011
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