Now a team of Californian scientists is working on developing a set of smart curtains the researchers believe could reduce a building’s energy use by half.

The team, led by Ali Javey, associate professor of electrical engineering and computer sciences at University of California, Berkley, has constructed the curtains from carbon nanotubes to respond to light by automatically closing when the light is at its brightest.

The carbon nanotubes are layered on top of one another and glued to a plastic polycarbonate membrane. As light is absorbed by the nanotubes and converted to heat, the polycarbonate backing responds to the light by bending, shaping and activating the curtains to block further heat from entering the windows.

“The advantages of this new class of photo-reactive actuator is that is very easy to make, and it is very sensitive to low-intensity light,” said Javey. “The light from a flashlight is enough to generate a response. We envision these in future smart, energy-efficient buildings. Curtains made of this material could automatically open or close during the day. During testing, the smart curtains have already proven to be highly sensitive and react to even low intensity light, which would make for the best energy efficiency.”

The curtains require no electricity, batteries or an operating system which is where the savings come into play.

While the technology may seem similar to the sun shade systems that react to sunlight, the scientists see this innovation as a “simpler” system with no power source required.

Architect Rael San Fratello has also explored every saving interiors with the HEX Curtain, a kinetic “light show” that not only brings light and warmth into a space but also offers a dynamic aesthetic.

The curtain features a series of  hexagonal “petals” covered by two operable shields. It is constructed from laser sintered nylon and is 3D printed in 27 inch by 22 inch  panels.

“The two shields have the ability to pivot open and closed,” San Fratello says on his website. “The shields are hinged at the bottom and threaded at the top. The top thread connects each shield to the one next to it. At the end of each row a rotary motor pulls the thread and slowly opens or closes the shields in tandem.”

Both these innovative projects demonstrate how energy reduction can work from the inside, with Javey’s smart curtain useful for larger, commercial applications.