It works by harnessing ultra-violet rays to break down dirt on the surface.The next shower washes the windows clean without the need for detergent.
The secret lies in a coating that causes water to slide down the glass without forming into separate droplets. Pilkington also insist the glass won't need optimum weather conditions to begin working. Its photo-catalytic properties ensure UV light reacts chemically with organic deposits even when it cloudy. However the company admits stubborn deposits such as bird droppings will take longer to be broken down.
And it might need a blast from a hose in periods of low rainfall to speed things along. The company says Activ will be available in the form of double-glazed units for replacements windows. These are expected to cost 15-20% more than the usual installed cost of PVC-U windows.