... water with built-in thermal energy storage2, Provides the capability to use exhaust heat, natural gas, ... 4, Uses R717 as natural refrigerant without damaging the environment.5, Phase change thermal energy storage ... radiation, 3200 insolation hours/year).7, Electricity saving is 417kW.h/m2 per year(irradiance: 800W/m2, the sun ... 370 kg/m2(irradiance: 800W/m2, the sun light hour per year: 3200 hours).