Display Energy Certificates (DEC) measure energy efficiency and are mandatory for all public buildings over 1,000m² with A being the most efficient and G being the least.
DECC says when it occupied the building in 2008 it had a DEC rating of G which has been gradually improved over the last four years. The latest step up in energy efficiency has resulted from the introduction of more occupancy controls on lighting, the installation of boiler load optimisation control units and the installation of variable speed drives to supply fans.
Based on current energy prices, DECC estimates it will achieve energy savings of around £156,000 during 2011/12 and even higher savings in 2012/13.
Climate change minister, Greg Barker, said: “The new higher DEC rating of C represents a great achievement for the department over the last four years. Only 23 percent of commercial buildings are rated C or above.
“Since 2008, the department has cut its HQ building’s energy consumption by 60 percent and slashed carbon emissions in half. This is even more impressive when you consider that staff numbers in the building have risen since DECC took it on.
“With the right commitment, large organisations can make a big difference to their overheads and to their environmental impact, and DECC’s achievement is proof of that.”