A device that measures the intensity of direct beam solar radiation.

A device mounted in the vent connector that closes the vent when the heating unit is not firing. This traps heat inside the heating system and house rather than letting it draft up and out the vent system.

The heat absorbed or released when a substance undergoes a change in temperature.

A long, underground metal or plastic pipe through which air is drawn. As air travels through the pipe it gives up some of its heat to the soil, and enters the house as cooler air.

A building energy auditing technique used to determine and/or locate air leaks in a building shell or envelope.

Any light source designed specifically to direct light a task or work performed by a person or machine.

A power line for supplying electricity within a specified area.

A facility or piece of equipment that produces electricity.

The unit of illuminance equivalent to 1lumen per square meter.

Turbines in which the rotor speed increases and decreases with changing wind speed, producing electricity with a variable frequency.

To heat a gaseous mixture to the temperature at which combustion takes place.

A type of insulation material with fine, closed cells, containing a mixture of air and refrigerant gas. This insulation has a high R-value, good moisture resistance, and high structural strength compared to other rigid insulation materials.

An apparatus for converting the energy available in the wind to mechanical energy that can be used to power machinery (grain mills, water pumps) and to operate an electrical generator.

A tube in which combustion gases from a combustion appliance are vented out of the appliance to the outdoors.

A heat storage system that uses a heat storage medium, and where the additional or removal of heat results in a change in temperature.

A colorless, pungent, gas (NH3) that is extremely soluble in water, may be used as a refrigerant; a fixed nitrogen form suitable as fertilizer.

The amount of energy service or useful energy delivered per unit of energy input. Often used in reference to lighting systems, where the visible light output of a luminary is relative to power input; expressed in lumens per Watt; the higher the efficacy v ...

Draft that is caused by temperature differences in the air.

A compound used to make certain types of solar photovoltaic cells.

A type of insulation, composed of small diameter pink, yellow, or white glass fibers, formed into blankets or batts, or used in loose-fill and blown-in applications.