Probably the most simplistic concept, an AC unit that cools from ice also uses very little energy. The unit freezes a large amount of water at night and turns it into ice. During the hottest part of the day, this AC doesn’t use a compressor, but ice to cool the refrigerant. When the ice melts, the regular AC system kicks in while the water is re-circulated and the process begins again for the next day.
Put the environment first and save on your bills at the same time. A sophisticated Green HVAC system is the way to go!