Researchers at University College London (UCL) claim that a “revolutionary” new type of window could cut cleaning costs especially in tall buildings and reduce heating bills by up to 40% thanks to a new combination of nano-scale engineering inspired by the eyes of moths, and thermochromic coating.

The prototype, revealed this week, has conical nanostructures engraved on its surface that trap air and prevent all but a tiny amount of water coming into actual contact with the glass. It means that rain hitting the glass turns into balls and roll right off, carrying dirt with them.

In normal glass raindrops cling and slide down more slowly, leaving a trail of residue.

The glass is also coated with a very thin (5-10 nanometre) film of vanadium dioxide which during cold periods keeps thermal radiation in and, during hot periods, keeps infrared radiation out. Vanadium dioxide is a cheap and abundant material, unlike silver- or gold-based coatings used by current energy-saving windows.

A third benefit, researchers say, is its ability to cut glare inside. The nano-scale “bumps” give the windows the same anti-reflective properties found in the eyes of moths and other creatures that have evolved to hide from predators.

Although the product is aimed at high rise buildings Home Extension Team hopes that the benefits will filter down to the domestic sector in the coming years.