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.

Describes the reliability of power plants. It refers to the number of hours that a power plant is available to produce power divided by the total hours in a set time period, usually a year.

A combustion heating appliance that vents the combustion by-products directly into the heated space. The latest models have oxygen-sensors that shut off the unit when the oxygen level in the room falls below a safe level.

A building structural element that is built onto a building's exterior along the inner edges of all the windows, and extending from the ground to the eaves. Wingwalls help ventilate rooms that have only one exterior wall which leads to poor cross ventilat ...

A popular term for "non-conventional" transportation fuels derived from natural gas (propane, compressed natural gas, methanol, etc.) or biomass materials (ethanol, methanol).

A slender threadlike spike of pure crystalline material, such as silicon.

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 component of a hydropower plant; a pipe that delivers water to the turbine.

A program of the U.S. Department of Energy (DOE) that implements energy legislation and presidential directives. FEMP provides project financing, technical guidance and assistance, coordination and reporting, and new initiatives for the federal government ...

A device that moves and/or circulates air and provides ventilation for a room or a building.

A pump for circulating the heat transfer fluid in a hydronic heating system.

As defined by the Energy Security Act (PL 96-294) of 1980, "any organic matter which is available on a renewable basis, including agricultural crops and agricultural wastes and residues, wood and wood wastes and residues, animal wastes, municipal wastes, ...

A method of preventing oxidation of the exposed metal in structures by imposing between the structure and the ground a small electrical voltage.

The area between the layers of glazing (panes) of a window.

A term used for the transparent or translucent material in a window. This material (i.e. glass, plastic films, coated glass) is used for admitting solar energy and light through windows.

The weight of a material per unit of volume compared to the weight of the same volume of water.

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.

Energy terms

That portion of supply air that is drawn from outside, plus any recirculated air that has been treated to maintain a desired air quality.

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.