The Department for Energy and Climate Change (DECC), which is responsible for promoting energy efficiency in the country, has the lowest possible energy efficiency rating for its headquarters in Whitehall Place in London. On the government's own seven-point scale from A-G, it comes in at G.
The energy efficiency ratings for 267 public buildings were published in May in response to a parliamentary question from the Conservatives. About 45% of the UK's carbon emissions come from energy use in buildings .
One in three government buildings have the lowest possible rating for energy efficiency. The Home Office, which moved into a newly built office only a few years ago, and the Department of Health were given the bottom rating, while, on average, government buildings scored an F.
In total, more than 70% were rated E or below, which means that they are less energy-efficient than the average buildings of their type. None scored the highest rating of A or even a B.
The highest for any public buildings were the Ministry of Justice and the Wales Office, both rated at C.
At the time, a spokesman for DECC pointed out the new department had only moved into its building in October, but was determined to make it more energy efficient: "This is not easy as our new home is a Grade II-listed heritage building and more than 100 years old - making it difficult to match the energy-efficiency standards of new buildings."