A lamp that consists of a sealed arc tube inside a glass envelope, or outer jacket. The inner arc tube is filled with elements that emit light when ionized by electric current. A ballast is required to provide the proper starting voltage and to regulate c ...

The measure of overall efficiency for a variety of appliances. For water heaters, the energy factor is based on three factors: 1) the recovery efficiency, or how efficiently the heat from the energy source is transferred to the water; 2) standby losses, o ...

The difference in electrical pressure (voltage) between any two points in an electrical system or between any point in an electrical system and the earth.

The torque at the bottom of a speed (rpm) versus torque curve. The torque developed by the motor is a percentage of the full-load or rated torque. At this torque the speed, the rotational speed of the motor as a percentage of synchronous speed is zero. Th ...

A measure of the relative flame spread, and smoke development, from a material being tested. The flame spread rating is a single number comparing the flame spread of a material with red oak, arbitrarily given the number 100 and asbestos cement board with ...

An optical device for concentrating light that is made of concentric rings that are faced at different angles so that light falling on any ring is focused to the same point.

A container that holds rock used as the thermal mass to store solar energy in a solar heating system.

A type of power inverter that produce a high quality (nearly sinusoidal) voltage, at minimum current harmonics.

A device built into or installed above a combustion appliance to assure the escape of combustion byproducts, to prevent backdrafting of the appliance, or to neutralize the effects of the stack action of the chimney or vent on the operation of the applianc ...

A form of solar concentrating collector that does not track the sun.

The duct(s) of a forced air heating/cooling system through which heated or cooled air is supplied to rooms by the action of the fan of the central heating or cooling unit.

The inner coil in a heat pump that, during the cooling mode, absorbs heat from the inside air and boils the liquid refrigerant to a vapor, which cools the house.

The use of two or more different fuels (e.g. wood and coal) simultaneously in the same combustion chamber of a power plant.

A term used to describe heat energy lost from a water heater tank.

A heat exchanger that transfers the heat contained in a liquid heat transfer fluid to air.

A type of solar thermal collector that has tubes (pipes) that the heat transfer fluid flows through that are connected to a flat absorber plate.

The liquid resulting when water vapor contacts a cool surface; also the liquid resulting when a vaporized working fluid (such as a refrigerant) is cooled or depressurized.

The process by which a power plant, apparatus, or building is approved for operation based on observed or measured operation that meets design specifications.

A condition that can occur in a solar collector if the working fluid does not circulate when sun is shining on the collector.

The process of degrading organic material (biomass) by microorganisms in aerobic conditions.