To disconnect a transmission and/or distribution line; a power line that is not carrying a current; to open a circuit.

The downward facing structural element that is directly opposite the floor.

A unit of heat containing 100,000 British thermal units (Btu).

Energy available as a result of motion that varies directly in proportion to an object's mass and the square of its velocity.

A type of combustion heating appliance in which the combustion gases are vented to the outside, either with a fan (forced) or by natural convection.

The potential energy available in a fuel as received, taking into account the energy loss in evaporating and superheating the water in the fuel. Equal to the higher heating value minus 1050W where W is the weight of the water formed from the hydrogen in t ...

The transparent or opaque sphere in an electric light that the electric light transmits through.

An enzyme complex, produced by fungi and bacteria, capable of decomposing cellulose into small fragments, primarily glucose.

In reference to solar energy systems, the angle that a solar collector is positioned above horizontal.

The mean wind speed over a specified period of time.

A type of impulse hydropower turbine where water passes through nozzles and strikes cups arranged on the periphery of a runner, or wheel, which causes the runner to rotate, producing mechanical energy. The runner is fixed on a shaft, and the rotational mo ...

A generic term for a glazed opening that allows daylight to enter into a building and can be opened for ventilation.

A type of heat pump that transfers heat from outdoor air to indoor air during the heating season, and works in reverse during the cooling season.

A mound of dirt next to exterior walls to provide wind protection and insulation.

The overall rate of heat loss from a building by means of transmission plus infiltration, expressed in Btu per hour, per degree temperature difference between the inside and outside.

A total life cycle cost divided into equal amounts.

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.

The transformation on a compound or material into one or more substances by heat alone (without oxidation). Often called destructive distillation. Pyrolysis of biomass is the thermal degradation of the material in the absence of reacting gases, and occus ...

A metric unit of energy or work; the energy produced by a force of one Newton operating through a distance of one meter; 1 Joule per second equals 1 Watt or 0.737 foot-pounds; 1 Btu equals 1,055 Joules.

An electricity supplier rate structure in which the per unit price of electricity decreases as the amount of energy increases. Normally only available to very large consumers.