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 ...

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

A power line for supplying electricity within a specified area.

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

The unit of magnetic field intensity equal to 1 dyne per unit pole.

As defined in the Energy Security Act (P.L. 96-294; 1980) as "any organic matter, including sewage, sewage sludge, and industrial or commercial waste, and mixtures of such matter and inorganic refuse from any publicly or privately operated municipal waste ...

Under the First Law of Thermodynamics, efficiency is the ratio of work or energy output to work or energy input, and cannot exceed 100 percent. Efficiency under the Second Law of Thermodynamics is determined by the ratio of the theoretical minimum energy ...

A WECS that is used to grind grain, and that typically has a high-solidity rotor; commonly used to refer to all types of WECS.

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

Generation of energy at the location where all or most of it will be used.

The rate of heat production by a steady current in any part of an electrical circuit that is proportional to the resistance and to the square of the current, or, the internal energy of an ideal gas depends only on its temperature.

A material that can be used to store thermal energy as latent heat. Various types of materials have been and are being investigated such as inorganic salts, eutectic compounds, and parrafins, for a variety of applications, including solar energy storage ( ...

A turbine that uses water pressure to rotate its blades; the primary types are the Pelton wheel, for high heads (pressure); the Francis turbine, for low to medium heads; and the Kaplan for a wide range of heads. Primarily used to power an electric generat ...

Draft that is caused by temperature differences in the air.

Gasoline fuel additives such as ethanol, ETBE, or MTBE that add extra oxygen to gasoline to reduce carbon monoxide pollution produced by vehicles.

A profile of how the wind speed changes with height above the surface of the ground or water.

The first law states that energy can not be created or destroyed; the second law states that when a free exchange of heat occurs between two materials, the heat always moves from the warmer to the cooler material.

An air conditioner consisting of one or more assemblies that move, clean, cool, and dehumidify air.

A thermal storage wall is a south-facing wall that is glazed on the outside. Solar heat strikes the glazing and is absorbed into the wall, which conducts the heat into the room over time. The walls are at least 8 in thick. Generally, the thicker the wall, ...

A light source composed of a metal base, a glass tube filled with an inert gas or a vapor, and base pins to attach to a fixture.