HVAC GLOSSARY - L

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Latent Cooling Load: (or Latent Load) The cooling load caused by moisture in the air. The net amount of moisture added to the inside air by plants, people, cooking, infiltration, and any other moisture source. The amount of moisture in the air can be calculated from a combination of dry-bulb and wet-bulb temperature measurements.

Latent Heat: Heat, that when added or removed, causes a change in state - but no change in temperature. A change in the heat content that occurs without a corresponding change in temperature, usually accompanied by a change of state (as from liquid to vapor during evaporation).

Life Extension: A term used to describe capital expenses which reduce operating and maintenance costs associated with continued operation of electric utility boilers and other equipment. Such boilers usually have a 40-year operating life under normal circumstances.

Life-Cycle Cost: Amount of money necessary to own, operate and maintain a building, system, plant, piece of equipment, etc., over its useful life.

Load: The amount of electric power supplied to meet one or more end user's needs. The amount of electric power delivered or required at any specific point or points on a system. The requirement originates at the energy consuming equipment of the consumers.

Load Building: Refers to programs that are aimed at increasing the usage of existing electric equipment or the addition of electric equipment. Examples include industrial technologies such as induction heating and melting, direct arc furnaces and infrared drying; cooking for commercia establishments; and heat pumps for residences. Load building should include programs that promote electric fuel substitution. The load building effects should be reported as a negative number, shown with a minus sign.

Load Estimate: A series of studies performed to determine the heating or cooling requirements of your home. An energy load analysis uses information such as the square footage of your home, window and door areas, insulation quality and local climate to determine the heating and cooling capacity needed by your furnace, heat pump or air conditioner. When referring to heating, this is often known as a Heat Loss Analysis, since a home's heating requirements are determined by the amount of heat lost through the roof, entry ways and walls.

Local Exhaust Ventilation: An industrial ventilation system that captures and removes contaminants emitted from nearby sources before dilution into ambient workplace air can occur. Make-Up Air (See Outdoor Air Supply).