SkyCool Systems is a startup company out of Stanford University that is commercializing an energy-efficient cooling method that takes advantage of the coldness of space. According to Aaswath Raman, cofounder of SkyCool Systems, one way to cut the amount of energy air-conditioning units use is to send heat into outer space.

The idea behind the technology is to use a natural phenomenon called radiative cooling. When an object emits thermal radiation, a portion of it is absorbed and reflected by the atmosphere. Another portion of this thermal radiation escapes into space, where conditions are significantly cooler. This can cause the object emitting the radiation to cool.

Engineers have know for some time now that radiative cooling can be useful for cooling buildings at night, but Raman and a colleague at Stanford decided it should be possible to achieve this radiative cooling during the day, too.

Other groups have been pursuing daytime radiative cooling over the past few years. ARPA-E recently began funding three groups to pursue technologies for thermal pants, which currently consume massive amounts of water.

Raman says his company is exploring a range of potential applications in buildings and other structures.

The group published a paper in Nature in which they proved that a device designed to combine the properties of three different materials cooled to nearly five degrees Celsius below the ambient air temperature. This research showed that “even during the hottest hours of the day, the cold darkness of the universe” could be used as renewable energy.

Raman and his co workers said their prototypes can significantly lower the temperature of water, making it possible to “plug this into a wide range of cooling systems” to remove heat from the air. An existing model for SkyCool’s general approach consists of techniques for applying optical coatings to make windows more energy efficient. Seeing as how two-thirds of U.S. homes have an air conditioning unit, this product could be used with the existing cooling systems to make the home more energy efficient.

It was recently found by Srinivas Katipamula, a staff scientist at the Pacific Northwest National Laboratory, that daytime radiative cooling could potentially reduce to energy usage of a medium-sized office building by up to 50%.