Britain’s Prince Charles may be a climate change champion, but his mother’s house is an environmental nightmare according to a team of surveyors from renewable energy firm Navitron. Buckingham Palace came in dead last in the firm’s energy efficiency survey of 170 London buildings.

Thermal imaging of the palace showed heat pouring out of the building through every available opening, including the roof, walls, and curtained windows. One survey team member mused that Buckingham Palace “is better at heating the air outside than inside”. That’s not a surprising result considering that the palace was built in the 1820s–a time when energy efficiency wasn’t a major concern.

The royal family probably knows about the palace’s energy issues–last year, the building racked up £2.2 million in utility bills. Insulating all 600 rooms of the palace could prove to be a daunting task, but Navitron suggests that draught-proofing the windows and adding secondary glazing might be a start.

The full “Dirty Dozen” list is below:

1. Buckingham Palace

2. DECC (Defra)

3. Ministry of Defence

4. Horse Guards Barracks

5. Shell Building

6. Home Office

7. Houses of Parliament

8. Treasury

9. Portcullis House

10. MI6 HQ

11. Albert Hall

12. St James’ Palace

[Via UK Daily Mail]