Air that is returned to a heating or cooling appliance from a heated or cooled space.

The local climate of specific place or habitat, as influenced by landscape features.

The demand of a consumer of electricity at the time of a power supplier's peak system demand.

Any wholly or partially enclosed space in which combustion takes place.

An electronic device that allows current to flow in one direction only.

A component of a heat pump that reverses the refrigerant's direction of flow, allowing the heat pump to switch from cooling to heating or heating to cooling.

An energy band in a semiconductor in which electrons can move freely in a solid, producing a net transport of charge.

The highest possible pressure in a fuel-air mixture before spontaneous ignition occurs.

A vehicle with an engine capable of operating on two different types of fuels.

Power plants, whose output depends on a factor(s) that cannot be controlled by the power generator because they utilize intermittent resources such as solar energy or the wind.

A building element that provides protection against the sun, wind, and precipitation.

A gasifier in which the feedstock (fuel) is suspended by the movement of gas to move it through the gasifier.

The amount of money required to secure a specified cash flow at a future date at a specified return.

The vacancy where an electron would normally exist in a solid; behaves like a positively charged particle.

The planting, cultivation, and harvesting of a single species of crop in a specified area.

A method of depositing thin semiconductor photovoltaic) films. With this method, physical processes, such as thermal evaporation or bombardment of ions, are used to deposit elemental semiconductor material on a substrate.

A measure of the moisture content of air; may be expressed as absolute, mixing ratio, saturation deficit, relative, or specific.

An insulation product made of a fibrous material or plastic foams, pressed or extruded into board-like forms. It provides thermal and acoustical insulation strength with low weight, and coverage with few heat loss paths.

A power plant that uses two thermodynamic cycles to achieve higher overall system efficiency; e.g.: the heat from a gas-fired combustion turbine is used to generate steam for heating or to operate a steam turbine to generate additional electricity.

Solar radiation reflected from the ground onto a solar collector.