“Smart glass” currently available reduces the need for air conditioning system by blocking heat from the sun in some ways. However, this type of systems still require electricity to operate. Now, the scientists from Australia’s Royal Melbourne Institute of Technology University have developed a coating that allows existing glass to become smart without electricity.

Composed of relatively inexpensive vanadium dioxide, the self-regulating coating is just 50-150 nanometers thick which is approximately 1,000 times thinner than a human hair.

At a surface temperature below 67 degrees Celsius, vanadium dioxide acts as an insulator, helping to keep indoor heat from escaping through the window glass while allowing the full spectrum of sunlight to enter from the outside. However, when the temperature exceeds 67 degrees Celsius, vanadium dioxide transforms into a metal that blocks heat-causing infrared solar radiation from entering. It means that there will be less needs for HVAC systems since the room will retain heat inside when the weather cools and blocks heat during summer. In addition, a dimmer can be used to control the level of transparency on the window.