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

The process of converting municipal solid waste to energy and/or recovering materials for recycling.

A type of combustion heating system in which combustion air is drawn directly from outside and the products of combustion are vented directly outside. These features are beneficial in tight, energy-efficient homes because they will not depressurize a home ...

To influence the demand on a power source.

A particle of light that acts as an individual unit of energy.

The direct, diffuse, and reflected solar radiation that strikes a surface.

A high-efficiency photovoltaic device containing two or more cell junctions, each of which is optimized for a particular part of the solar spectrum.

A system in which a working fluid is used over and over without introduction of new fluid, as in a hydronic heating system or mechanical refrigeration system.

A slightly sloped roof, usually with a tar and gravel cover. Most commercial buildings use this kind of roof.

An electrical device that resists electric current flow.

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

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

The highest wind speed at which a wind turbine stops producing power.

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.

A cooling device that uses mechanical energy to produce chilled water.

Materials with high thermal energy storage capacity contained in or part of a building's walls, floors, or freestanding elements.

A complete lighting unit consisting of a lamp(s), housing, and connection to the power circuit.

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.

Air that provides the necessary oxygen for complete, clean combustion and maximum heating value.

A self-contained toilet that use the process of aerobic decomposition (composting) to break down feces into humus and odorless gases.