BRUSSELS When all else fails, the British secret services are the perfect excuse - and London has rolled them out as an argument against one of the most complex pieces of legislation on the EU agenda.
In theory, energy saving should be obvious and simple, especially in times of economic crisis.
In practice, it has generated multiple amendments and mathematical formulae, Byzantine even by EU standards, as governments find ways to dodge targets on increased energy savings through more efficient buildings.
One of many heated debates has focused on how many public buildings should be overhauled to make them use less energy.
The current proposal is for a proportion of the total space to be renovated each year, but EU member states have been whittling away at how many buildings should be included.
To a growing list of exceptions, Britain has added barracks and offices for the armed forces and other staff employed by national defence authorities "capable of being shared with other central government authorities", in comments on the draft directive seen by Reuters.
"There are also serious security issues over disclosing the location of a significant number of buildings owned by public bodies," another comment said.
Green campaigners said that was code for property used by military intelligence and that there was no reason why it should not be well-insulated.
On the contrary, reducing reliance on imported oil from volatile regions, cited as a reason for Western military intervention, could help to reduce the need for counter-terrorism work and safe houses in the first place.
"It's an obvious attempt to protect the location of the MI6 and MI5 safe houses," said Brook Riley, a campaigner at Friends of the Earth.
"It's the classic British civil servant excuse - blame the spooks, raise security concerns."
"But the UK will have to come up with a better reason to oppose energy savings legislation than the risk of disclosing MI6 safe houses, even if it's doubtless easier to get suspects to confess in damp, badly insulated rooms."
A British diplomat in Brussels said Britain was opposed to target-setting.
"We don't think the directive has done the necessary cost-benefits analysis to set a target for public buildings," the diplomat said.
(Reporting by Barbara Lewis, editing by Paul Casciato)