Intelligent windows self-clean and regulate temperature of buildings

Buildings consume 40 per cent of the energy used in the developed world, with heating and cooling accounting for around two-thirds of this.

The smart windows, which have been developed at University College London (UCL) with funding from EPSRC, could help reduce the cost of cleaning the large number of windows in modern office buildings, cut energy use and slash heating bills by up to 40 per cent.

The windows are engraved with a series of pencil-like conical nanostructures. These trap air and ensure only a tiny amount of water touches the surface of the glass.

As a result, any rain hitting the windows forms into spherical droplets that simply roll off the glass surface, picking up dust and dirt in their path as they do so.

In contrast, raindrops hitting conventional windows cling to the glass, causing them to slide down it and leave streaks and dirt behind.

The pattern of the nanostructures also gives the windows the same anti-reflective properties as the eyes of creatures such as moths, which allow them to hide from predators. This reduces glare by cutting the amount of light reflected internally within a room, to less than five per cent. This compares with 20-30 per cent for other prototype energy saving windows.