Four aerospace engineers have created a zero-emission air-conditioning system powered by the sun's thermal energy.

The team—Yann Vitupier, Charles Daniel, Marie Nghiem and Yannick Godillot—first worked together at Franco-Italian aerospace firm Thales Alenia Space, helping engineer sophisticated satellites such as the European Space Agency’s Goce gravity mapper. Based on their expertise from developing satellite thermal control and cooling systems, they founded the French company Helioclim to develop a novel system using solar energy to power air conditioning and central heating, as well as cool refrigerators and heat water.

The system uses curved solar mirror troughs spread across a building’s roof to concentrate the sun’s power onto tubes to heat water to 200 degrees Celsius. Using a proprietary—and at this time confidential—process, the pressurized water enters another unit to provide both hot and cold water.

The solar collector for Helioclim's zero-emission air-conditioning system turns to follow the sun. Image credit: Helioclim.The temperature of the emerging water can be set at anywhere between –60 degrees Celsius and +65 degrees Celsius, which is then circulated to create the required temperatures for the different parts of the building. Below 0 degrees Celsius, a water-ammonia mixture is used as the refrigerant.

Helioclim's system can connect with a building’s existing chilled and hot water systems and can function on a cloudy day from stored energy or power from other sustainable sources, such as biomass.

“It’s important to understand that we are not generating electricity from solar panels to power traditional air-conditioning machines,” Nghiem notes. “Instead, we are using the sun’s thermal energy to heat water inside the units and reach the required temperatures.”

Although a number of other companies are also designing solar thermal systems, the engineers say that their version is unique in that it can provide cooling down to –60 degrees Celsius and heating up to +200 degrees Celsius.