The building loses more heat than Buckingham Palace, the Reichstag, Scottish Parliament and the Welsh Assembly, costing the taxpayer £7,191 a year in wasted energy, new technology has exposed.
Scientists worked out the loss using infra red image study, which provides quantified C02 loss and heat loss through thermal image.
In contrast with Parliament, the Welsh Assembly leaks just £95.98 a year, researchers from IRT Energy said. Buckingham Palace loses £1,038, the Reichstag loses £599.25, while the Scottish Parliament leaks £463.40.
The least green landmark the technology recorded was Manchester Piccadilly, which loses £18,217.
The original software quantifies the data in a traditional infra red image to disclose just how "green" key landmark buildings really are.
Stewart Little, from IRT, said: "The technology behind IRT Energy is so accurate and the analysis so quick, for the first time it is now physically possible to survey and analyse every home in the country, with obvious implications for the Government's environmental targets.
"With thermal imaging technology being developed for use in everything from breast cancer detection to new car technology and IRT Energy's ability to handle millions of images, the possible for future applications is accurately boundless."