By Charles Clover

Environment Editor

THE luxurious new Whitehall offices of Lord Falconer, the Lord Chancellor, are to use an air conditioning system that contains powerful global warming gases - against the Government's own procurement guidelines.

The system has been installed as part of the £99.5 million refurbishment of 50 Queen Anne's Gate, a 1970s building formerly occupied by the Home Office, into which the Department for Constitutional Affairs moves next year.

The disclosure, in a Commons written answer, that the air conditioning system will contain HFCs, a group of chemicals with 1,400 times the global warming potential, molecule for molecule, of carbon dioxide is likely to embarrass the Government at the start of the global climate change talks which begin in Nairobi, Kenya, this week.

The environmental group Greenpeace said the Church of England has installed an air conditioning system in Church House, an older building only a stone's throw away, which uses much more benign and energy-efficient alternatives.

Harriet Harman, a Constitutional Affairs Minister, told the Commons. "The Department's policy is for natural ventilation for buildings whenever possible and only to install cooling Systems where absolutely necessary.

"Where cooling cannot be avoided, designers are required to investigate systems which minimise environmental impact in terms of ozone depletion and global warming.