At Bowater House the windows will be made of a
new kind of glass which has been developed by Pilkington Glass
The Windows are very hi-tech. They are maybe the best windows
available because they can keep lots of heat in a room.
Once heat has entered through the windows, the windows will not
let it escape.
The diagram above shows just how Pilkington K glass works. The
Windows also reflect heat from fires and radiators back into the
room.
Ordinary double-glazing would allow this heat to escape.
The Pilkington K glass is proven to be up to 30% better
insulation then other double-glazed windows.

Here is a picture of an installed window.
Energy saving features index. Bowater House menu