Yorkshire Water's new headquarters in Buttershaw have been kitted out with windows which open and close by themselves.

The new £6.9 million building, also has lights which switch off when no one is in the room.

Staff at the 17,500 sq ft, three-storey building, which has taken 60 weeks to build and has been named Midway, can also enjoy an in-house gym and fitness centre. More than 400 employees have moved to the open-plan offices which were developed by consultants EC Harris and engineers Ove Arup.

David Rigby, regional managing partner at EC Harris, said: "Yorkshire Water is unusual as a company in designing its new office with such a high regard to energy conservation.

"The Midway building incorporates intelligent convection heating - you can set the temperature and the ventilation will adjust using strategically placed censors. There's automatic lighting, which can detect people in any area and at any workstation. And to keep the office cool in the summer, solar shading has been created on the south side, with the exterior insulated by special tiles."

Tony Paul, YW's facilities manager, added: "This move completes a large part of Yorkshire Water's accommodation strategy, which was started in 1995. "The whole essence of the move is to create a better working environment. We can now close our Broadacre House office in the centre of Bradford and remove portable buildings from the Buttershaw site." Of the equipment, Mr Paul explained: "If we want to get the best people to work for the company and retain them, we have to provide things like this."