Energy Efficient

As applied to buildings, generally indicating the existence of extra insulation, weatherproofing, and/or special features and equipment designed to reduce the cost of energy for heating, cooling and hot water.Example: An energy efficient home might have an extra layer of insulation in the attic and walls, a relatively airtight exterior, a heat pump, and a solar hot water heater. An energy efficient furnace might be designed to burn fuel more completely and capture more of the heat generated.