A term used to describe short and long-term affects on the Earth's climate as a result of human activities such as fossil fuel combustion and vegetation clearing and burning.

An energy system in which the fuel production equipment is in close proximity, or connected to, the fuel using equipment.

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.

As defined by the Comprehensive National Energy Act of 1992 (or the Energy Policy Act; EPAct): any organic matter from a plant which is planted for the exclusive purpose of being used to produce energy." This does not include wood or agricultural wastes o ...

A type of heating system in which the heat transfer fluid circulates from the heating component to a heat exchanger that is immersed in a heat storage media, passing its heat to the storage media without physically contacting it.

Legal documents that regulate construction to protect the health, safety, and welfare of people. Codes establish minimum standards but do not guarantee efficiency or quality.

A value that describes the ability of a material to conduct heat. The number of Btu that flow through 1 square foot of material, in one hour. It is the reciprocal of the R-Value (U-Value = 1/R-Value).

A ratio of the work or useful energy output of a system versus the amount of work or energy inputted into the system as determined by using the same energy equivalents for energy in and out. Is used as a measure of the steady state performance or energy e ...

A term used for lighting appliances; the ratio of lumens received on a flat surface to the light output, in lumens, from a lamp; used to evaluate the effectiveness of luminaries in delivering light.

The use of two or more different fuels (e.g. wood and coal) simultaneously in the same combustion chamber of a power plant.

The generation of electricity or shaft power by an energy conversion system and the concurrent use of rejected thermal energy from the conversion system as an auxiliary energy source.

A class of energy producer that produces both heat and electricity from a single fuel.

As a component of a heating or cooling appliance, rows of tubing or pipe with fins attached through which a heat transfer fluid is circulated and to deliver heat or cooling energy to a building.

The ratio of the coincident, maximum demand or two or more loads to the sum of their noncoincident maximum demand for a given period; the reciprocal of the diversity factor, and is always less than or equal to one.

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

The low effective temperature of the sky on a clear night.

The component of a solar energy heating system that collects solar radiation, and that contains components to absorb solar radiation and transfer the heat to a heat transfer fluid (air or liquid).

The ratio of solar radiation captured and transfered to the collector (heat transfer) fluid.

The fluid, liquid (water or water/antifreeze solution) or air, used to absorb solar energy and transfer it for direct use, indirect heating of interior air or domestic water, and/or to a heat storage medium.

The angle that a solar collector is positioned from horizontal.