Currents from electrical equipment within a facility that can overheat wires and transformers.

Heat Exchanger

A mechanical device used to transfer heat from one medium to another, such as from water to air.

Heat Gain

The amount of heat flowing into a home as a result of sunshine, warm air leakage, warming of the walls and roof, and heat given off by people and equipment.

Heat Loss

The amount of heat in a building that is lost as a result of heat flow through walls, windows, and roof, and air leakage through many parts of the thermal envelope.

Heat Pump

A year-round space-conditioning system capable of both heating and cooling. A heat pump always delivers more BTUs than are in the electrical energy used to operate it.

Heat Pump Water Heater

Single unit that both heats water and provides spot cooling.

Heat Recovery Unit

A device used to capture a portion of the heat expelled from an air conditioning or heat pump compressor. It is used for domestic water heating, in essence providing “free” hot water.

Heat Transfer

The passage of heat from a warm body to a cooler one.

Heating Seasoned Performance Factor (HSPF)

Total heating output of a heat pump during its normal annual usage period for heating, divided by total electric power input during the same period.

High Bay Lighting

Used in areas where the bottom of the light fixture is more than 20 feet above the floor, typical high bay fixtures have a 15 – 18″ open reflector allowing for a more concentrated beam spread with a prominent downward component. High wattage sources in fluorescent and HID are usually required in order to properly illuminate the space.