Engineers from California and Spain have created a new type of smart glass that selectively blocks light and heat under the control of an electrical switch. The discovery could help homeowners conserve energy and save money on their utility bills.

The U.S. Department of Energy estimates that windows account for 30 percent of total building energy costs. Some people have reported up to a 70 percent return on their investment after replacing old drafty windows with new energy-efficient models.

Read more: Glass Windows With A 'Cardiovascular System'

Created by scientists at the Lawrence Berkeley National Laboratory, the innovative windows are a composite of two special materials. First is a glass matrix composed out of niobium oxide, which is a compound that can filter visible light. Next, this matrix was infused with nanocrystals made out of tin-doped indium oxide. This material can block infrared beams of light, keeping air on the other side of the glass from heating up.

Passing a short burst of electrical current through the glass changes the chemical nature of the two materials and alters the orientation of their molecules. This allows them to block both light and heat.

Proposed Model For A Universal Smart Window. A dual-band electrochromic material has been developed by linking tin-doped indium oxide nanocrystals to an amorphous niobium oxide matrix. These nanocomposite films can selectively block visible and near-infrared light, allowing energy savings in buildings by dynamically controlling daylight and solar heat through windows. Credit: Anna Llordés, Delia Milliron and Creative Services, Lawrence Berkeley National Lab. Credit: Anna Llordés, Delia Milliron and Creative Services, Lawrence Berkeley National Lab.

Moreover, each material responds to a different voltage, so heat and light could be blocked independently.

These new smart windows could offer a hi-tech option for temperature regulation of a person’s home that also alleviates the need for purchasing window blinds or shades.

Source: Llordés A, Garcia G, Gazquez J, Milliron DJ. Tunable near-infrared and visible-light transmittance in nanocrystal-in-glass composites. Nature. 2013.