For valves and fittings, implies that they are suitable for working pressures between 125 to 175 pounds per square inch.

A window glass that has been coated with a reflective film and is useful in controlling solar heat gain during the summer.

A measure of the percent of moisture actually in the air compared with what would be in it if it were fully saturated at that temperature. When the air is fully saturated, its relative humidity is 100 percent.

The average power output of a wind energy conversion system at a given mean wind speed based on a Raleigh frequency distribution.

A building element that shades windows, walls, and doors from direct solar radiation and protects these elements from precipitation.

A device for measuring power consumption.

The supportive structure of a building.

The fine liquid or solid particles contained in combustion gases. The quantity and size of particulates emitted by cars, power and industrial plants, wood stoves, etc are regulated by the U.S. Environmental Protection Agency.

A solar energy concentrating technology that uses a linear receiver that tracks the focal area of a reflector or array of reflectors.

A characteristic applied to domestic water heaters that is the amount of gallons raised 100 degrees Fahrenheit per hour (or minute) under a specified thermal efficiency.

A mechanism used by electric utilities to determine prices for electricity; typically defines rates according to amounts of power demanded/consumed during specific time periods.

A device used to transfer heat from a fluid (liquid or gas) to another fluid where the two fluids are physically separated.

Power generation equipment or system capacity to meet peak power demands.

The angle at which a solar collector or module is set to face the sun relative to a horizontal position. The tilt angle can be set or adjusted to maximize seasonal or annual energy collection.

Parasitic resistance to current flow in a cell due to mechanisms such as resistance from the bulk of the semiconductor material, metallic contacts, and interconnections.

A mainly flat surface for transmitting radiant energy.

A type of solar heating system that circulate warm water from storage through the collectors and exposed piping whenever freezing conditions occur; obviously a not very efficient system when operating in this mode.

A device used to remove particulate matter from the waste gasses of a combustion power plant.

A solar thermal system that has one tank for storing solar heated water to preheat the water in a conventional water heater.

Air that is taken from the outdoors.