Now here's a public service which seems to have a very good record of improving the energy efficiency of its headquarters over the past two years.
You might think that they would want to boast about it, but in this case it's secret and you're not meant to know.
Since 2011 the Secret Intelligence Service, otherwise known as MI6, has cut its carbon dioxide emissions and shifted from being in the worst category for energy efficiency to rating better than would be typical for its kind of building.
This is disclosed in the organisation's official Display Energy Certificate, which I reveal here. Until recently this document was publicly available on the internet, despite this being contrary to the relevant regulations, but it has now been removed.
The certificate states the address for the MI6 headquarters at Vauxhall Cross in central London. It gives "GCB" as the occupier of the building. This stands for Government Communications Bureau, which is sometimes used as a cover name for MI6.
The document shows that since 2011 the building's energy rating has improved from 166, a very low score which would put it in the least efficient grouping, to a much better 88. Carbon dioxide emissions have fallen by around 10%, but it doesn't use any renewable sources of energy.
This change has been achieved in a building which must doubtless contain complex arrays of sophisticated electronic equipment.
Public buildings are required to display energy performance certificates with details of their energy efficiency, in line with a European Union directive. Generally the certificates should also be published on the website of the non-domestic energy performance register, to maximise transparency and enable public scrutiny.
However some buildings are meant to be excluded from this public register. This includes those belonging to the security agencies (as well as prisons, and those used by the armed forces and the royal family).
The GCB/MI6 certificate was however available on the register until recently to anyone who searched for it using the building's postcode. After I discovered this, saved a copy and sought a comment from the service on its impressive improvements in efficiency, the document was taken down. And no comment of any kind has been forthcoming.
If you now search the register using its reference number, you receive a message that the information for that number "has been cancelled".
The register also includes copies of reports from energy inspectors who advise building owners on how to improve efficiency.
The advisory report for MI6 also refers to the Government Communications Bureau. It specifies the building type as "Covered Car Park; Fitness And Health Centre; General Office; Restaurant".
Presumably this indicates that the building's facilities include a staff canteen, gym and car park, but the term "general office" is a suitably anonymous account of the top secret work that goes on inside.
The energy assessor's recommendations in 2011 included changes to the air conditioning system, lighting levels and power-saving settings on computers - as well as encouraging staff to make less use of the lifts.
This report has also now been removed from the register website and is described as "cancelled". But it's good to know the nation's spies are taking the stairs and switching off the lights before they go home.
This all raises the question as to whether security bodies should be entirely excluded from the system for scrutiny of the energy efficiency records of public authorities. Although intelligence agencies are not covered by the Freedom of Information Act, they are subject to the Environmental Information Regulations which can allow access to environmental information about them when this is considered to be in the public interest.
The BBC has been engaged in a separate long-running case seeking to persuade the government that the entire energy efficiency dataset should be made publicly available in one go, to make it easier to compare different buildings and carry out a national analysis of all the data. This has yet to be resolved.