Reduce your carbon footprint and utility bills at the same time. WaterFurnace geothermal systems use the free, renewable energy found in your own back yard to save up to 70% on heating, cooling, and hot water costs. Your BEST choice for green ventilation, RenewAire ERVs exhaust stale air, bring in fresh air and save energy year-round. Radiant heat is the same form of energy as light.