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 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 ...

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

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 unit of power equal to 1 billion Watts; 1 million kilowatts, or 1,000 Megawatts.

The complex process by which organic matter is decomposed by anaerobic bacteria. The decomposition process produces a gaseous byproduct often called "biogas" primarily composed of methane, carbon dioxide, and hydrogen sulfide.

The mean wind speed over a specified period of time.

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

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

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 ...

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 heating capacity of a steam boiler; expressed in Btu per hour (Btu/h), or horsepower, or pounds of steam per hour.

The pressure corresponding to the outlet velocity of a fan; the kinetic energy per unit volume of flowing air.

Energy terms

A total life cycle cost divided into equal amounts.

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 generic term for liquefied and pressurized gas, ordinarily butane, propane, or a mixture of the two, contained in a cylinder for domestic use.