A frequently used room or area that is maintained at a more comfortable level than the rest of the house; also known as a "warm room."

A battery that uses lithium in the negative electrode and a metal sulfide in the positive electrode, and the electrolyte is molten salt; can store large amounts of energy per unit weight.

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

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.

The heat produced by combusting a specific quantity and volume of fuel in an oxygen-bomb colorimeter under specific conditions.

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

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

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

A current carrier, either an electron or a hole, that is in the minority in a specific layer of a semiconductor material; the diffusion of minority carriers under the action of the cell junction voltage is the current in a photovoltaic device.

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

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 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 solar collector in which the absorber is contained in a sealed glass tube, thereby providing for relatively high temperature heat gain.

A heating unit where heat is distributed by means of convection or fans.

A type of window having two layers (panes or glazing) of glass separated by an air space. Each layer of glass and surrounding air space reradiates and traps some of the heat that passes through thereby increasing the windows resistance to heat loss (R-val ...

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

A measure of the surface burning characteristics of a material.

That part of an electricity bill that is based on the amount of electrical energy consumed or supplied.

A curve that displays load values on the horizontal axis in descending order of magnitude against the percent of time (on the vertical axis) that the load values are exceeded.

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