A new 'smart' window system will turn dark when the sun comes out - and then instantly become crystal clear when it's colder, so that you can save on heating bills by soaking up heat from the sun.
The new material - unveiled by scientists - allows a cheap and automatic system to keep houses cool in summer, and warm in winter.
Other 'dimmer' glasses rely on manual control using expensive equipment such as Crestron home-automation panels.
Ho Sun Lim, Jeong Ho Cho, Jooyong Kim and Chang Hwan Lee, writing in the journal ACS Nano, point out there is a huge appetite for 'smart' glass for skylights, windows - and even in car windows.
Hitachi recently unveiled SPD 'smart glass' which will be used in homes - and future models of Mercedes-Benz.
The company can manufacture 4.3 million square feet of SPD-Smart film per year from its new production facility.
The researchers, however, claim their 'smart glass' is faster - and will save users more money than any rival.
Previous 'smart windows' tended to be costly, and deteriorate rapidly - as well as using various toxic products in their production. The researchers set out to develop a smart window that overcomes these drawbacks.
They discovered that using a polymer, a layer of ions, and a solvent such as methanol was an inexpensive and less harsh way to make a stable, robust smart window.
It has the added advantage of being extremely tunable — quickly and easily switching from 100% opaque to almost completely clear in seconds.
'To our knowledge, such extreme optical switching behavior is unprecedented among established smart windows,' the authors state.
'This type of light control system may provide a new option for saving on heating, cooling and lighting costs through managing the light transmitted into the interior of a house.'
