Air Conditioning Glossary

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

 

Absorptance: The ratio of the radiation absorbed by a surface to the total energy falling on that surface described as a percentage.

Absorption Cycle: Absorption chillers use a thermal or chemical process to produce refrigeration. There is no mechanical compression of the refrigerant taking place within the machine as with traditional vapor compression type chillers. Most commercial absorption chillers use lithium bromide (a salt) and water.

ACBM: Acronym for "asbestos-containing building material."

Accurator: A metering device that feeds the proper amount of liquid refrigerant into the evaporator.

Account classification: The way in which suppliers of electricity, natural gas, or fuel oil classify and bill their customers. Commonly used account classifications are "Residential," "Commercial," "Industrial," and "Other." Suppliers' definitions of these terms vary from supplier to supplier. In addition, the same customer may be classified differently by each of its energy suppliers.
Account of others (natural gas): Natural gas deliveries for the account of others are deliveries to customers by transporters that do not own the natural gas but deliver it for others for a fee. Included are quantities covered by long-term contracts and quantities involved in short-term or spot market sales.

Acid Deposition: a term for the conversion of sulfur oxide and nitrogen oxide emissions into acidic compounds which precipitate in rain, snow, fog, or dry particles

Acid mine drainage: This refers to water pollution that results when sulfur-bearing minerals associated with coal are exposed to air and water and form sulfuric acid and ferrous sulfate. The ferrous sulfate can further react to form ferric hydroxide, or yellowboy, a yellow-orange iron precipitate found in streams and rivers polluted by acid mine drainage.

Acid rain: Also called acid precipitation or acid deposition, acid rain is precipitation containing harmful amounts of nitric and sulfuric acids formed primarily by sulfur dioxide and nitrogen oxides released into the atmosphere when fossil fuels are burned. It can be wet precipitation (rain, snow, or fog) or dry precipitation (absorbed gaseous and particulate matter, aerosol particles or dust). Acid rain has a pH below 5.6. Normal rain has a pH of about 5.6, which is slightly acidic. The term pH is a measure of acidity or alkalinity and ranges from 0 to 14. A pH measurement of 7 is regarded as neutral. Measurements below 7 indicate increased acidity, while those above indicate increased alkalinity.

Action Level: A term used to identify the level of indoor radon at which remedial action is recommended. (EPA's current action level is 4 pCi/L.)

Active power: The component of electric power that performs work, typically measured in kilowatts (kW) or megawatts (MW). Also known as "real power."  The terms "active" or "real" are used to modify the base term "power" to differentiate it from Reactive Power.  See Power, Reactive Power, Apparent Power

Active Solar Energy System: A system designed to convert solar radiation into usable energy for space, water heating, or other uses. It requires a mechanical device, usually a pump or fan, to collect the sun's energy.

Active Solar Energy: Solar radiation used by special equipment to provide space heating, hot water or electricity.
Active solar: As an energy source, energy from the sun collected and stored using mechanical pumps or fans to circulate heat-laden fluids or air between solar collectors and a building.

Actual peak reduction: The actual reduction in annual peak load (measured in kilowatts) achieved by customers that participate in a utility demand-side management (DSM) program. It reflects the changes in the demand for electricity resulting from a utility DSM program that is in effect at the same time the utility experiences its annual peak load, as opposed to the installed peak load reduction capability (i.e., potential peak reduction). It should account for the regular cycling of energy efficient units during the period of annual peak load.

Addition: An alteration to an existing building that increases conditioned space.

Adjustable speed drives: Drives that save energy by ensuring the motor's speed is properly matched to the load placed on the motor. Terms used to describe this category include polyphase motors, motor oversizing, and motor rewinding.
Adjusted Coefficient of Performance (ACOP): A standard rating term used to rate the efficiency of heat pumps. ACOP was replaced by Heating Seasonal Performance Factor (HSPF) in 1988.

Adjusted electricity: A measurement of electricity that includes the approximate amount of energy used to generate electricity. To approximate the adjusted amount of electricity, the site-value of the electricity is multiplied by a factor of 3. This conversion factor of 3 is a rough approximation of the Btu value of raw fuels used to generate electricity in a steam-generation power plant.
Adverse Health Effects: health effects from exposure to air contaminants that may range from relatively mild temporary conditions, such as minor eye or throat irritation, shortness of breath, or headaches, to permanent and serious conditions such as birth defects, cancer, or damage to lungs, nerves, liver, heart, or other organs

Adverse Hydro: Water conditions limiting the production of hydroelectric power. In years having below–normal levels of rain and snow, and in seasons having less–than–usual runoff from mountain snowpack, there is then less water available for hydro energy production.

Adverse water conditions: Reduced streamflow, lack of rain in the drainage basin, or low water supply behind a pondage or reservoir dam resulting in a reduced gross head that limits the production of hydroelectric power or forces restrictions to be placed on multipurpose reservoirs or other water uses.

Aerosol: particle of solid or liquid matter that can remain suspended in the air because of its small size (generally under one micron)

Afforestation: Planting of new forests on lands that have not been recently forested.

After Market: A broad term that applies to any change after the original purchase, such as adding equipment not a part of the original purchase. As applied to alternative fuel vehicles, it refers to conversion devices or kits for conventional fuel vehicles.

Aggregator: An entity responsible for planning, scheduling, accounting, billing, and settlement for energy deliveries from the aggregator's portfolio of sellers and/or buyers. Aggregators seek to bring together customers or generators so they can buy or sell power in bulk, making a profit on the transaction.

AHU: See "Air Handling Unit."

Air Change: The replacement of a quantity of air in a space within a given period of time, typically expressed as air changes per hour. If a building has one air change per hour, this is equivalent to all of the air in the building being replaced in a one–hour period with new fresh air.

Air cleaner: A device using filters or electrostatic precipitators to remove indoor-air pollutants such as tobacco smoke, dust, and pollen. Most portable units are 40 watts when operated on low speed and 100 watts on high speed.

Air Cleaning: An IAQ control strategy to remove various airborne particulates and/or gases from the air. The three types of air cleaning most commonly used are particulate filtration, electrostatic precipitation, and gas sorption.
Air collector: A medium-temperature collector used predominantly in space heating, utilizing pumped air as the heat-transfer medium.

Air Conditioner: An assembly of equipment for air treatment consisting of a means for ventilation, air circulation, air cleaning, and heat transfer (either heating or cooling). The unit usually consists of an evaporator or cooling coil, and an electrically–driven compressor and condenser combination.

Air conditioning intensity: The ratio of air-conditioning consumption or expenditures to square footage of cooled floor space and cooling degree-days (base 65 degrees F). This intensity provides a way of comparing different types of housing units and households by controlling for differences in housing unit size and weather conditions. The square footage of cooled floor space is equal to the product of the total square footage times the ratio of the number of rooms that could be cooled to the total number of rooms. If the entire housing unit is cooled, the cooled floorspace is the same as the total floorspace. The ratio is calculated on a weighted, aggregate basis according to this formula:

Air conditioning: Cooling and dehumidifying the air in an enclosed space by use of a refrigeration unit powered by electricity or natural gas. Note: Fans, blowers, and evaporative cooling systems ("swamp coolers") that are not connected to a refrigeration unit are excluded.

Air Cooled: An air conditioning unit that uses a fan to exhaust heat from the condenser coil to the outdoors.

Air-Cooled System: An air conditioning system that uses freon as a refrigerant and air as a condensing medium.

Air Diffuser: A grille designed to direct airflow into desired directions.

Air Exchange Rate: The rate at which outside air replaces indoor air in a space. Expressed in one of two ways: the number of changes of outside air per unit of time air changes per hour (ACH); or the rate at which a volume of outside air enters per unit of time - cubic feet per minute (cfm).

Air Film Coefficient: A measure of the heat transfer through an air film. (ASHRAE Table 1, ASHRAE Handbook, 1985 Fundamentals)

Air Film: A layer of still air adjacent to a surface which provides some thermal resistance.

AIR HANDLING UNIT (AHU): Equipment that includes a blower or fan, heating and/or cooling coils, and related equipment such as controls, condensate drain pans, and air filters that moves heated or cooled air throughout a home's ductwork. Does not include ductwork, registers or grilles, or boilers and chillers.

AIR PASSAGES: Openings through or within walls, through floors and ceilings, and around chimney flues and plumbing chases, that permit air to move out of the conditioned spaces of the building.

Air pollution abatement equipment: Equipment used to reduce or eliminate airborne pollutants, including particulate matter (dust, smoke, fly, ash, dirt, etc.), sulfur oxides, nitrogen oxides (NOx), carbon monoxide, hydrocarbons, odors, and other pollutants. Examples of air pollution abatement structures and equipment include flue-gas particulate collectors, flue-gas desulfurization units and nitrogen oxide control devices.

Air Pollution: Unwanted particles, mist or gases put into the atmosphere as a result of motor vehicle exhaust, the operation of industrial facilities or other human activity.

Air Quality Standard (AQS): the prescribed level of a pollutant in the outside air that should not be exceeded during a specific time period to protect public health. Established by both federal and state governments

Air: so-called "pure" air is a mixture of gases containing about 78 percent nitrogen; 21 percent oxygen; less than 1 percent of carbon dioxide, argon, and other inert gases; and varying amounts of water vapor

Air-Conditioning Intensity = Btu for Air Conditioning/(Cooled Square Feet * Cooling Degree-Days)

Air–to–Air Heat Exchanger: A device with separate air chambers that transfers heat between the conditioned air being exhausted and the outside air being supplied to a building.

Alcohol Fuels: A class of liquid chemicals that have certain combinations of hydrogen, carbon and oxygen, and that are capable of being used as fuel.

ALLERGEN: A substance capable of causing an allergic reaction because of an individual's sensitivity to that substance.

ALLERGIC RHINITIS: Inflammation of the mucous membranes in the nose that is caused by an allergic reaction.

Alteration: Any change or modification to a building's construction. See Addition.

Alternating Current (AC): Flow of electricity that constantly reverses its direction at regularly recurring intervals between positive and negative sides.  Almost all power produced by electric utilities in the United States moves in current that shifts direction at a rate of 60 times per second (60Hz).

Alternative (transportation) Fuels as defined by the National Energy Policy Act (EPAct): methanol, denatured ethanol and other alcohols, separately or in mixtures of 85 percent by volume or more (or other percentage not less than 70 percent as determined by U.S. Department of Energy rule) with gasoline or other fuels; CNG; LNG; LPG; hydrogen; “coal–derived liquid fuels;” fuels “other than alcohols” derived from “biological materials;” electricity, or any other fuel determined to be “substantially not petroleum” and yielding “substantial energy security benefits and substantial environmental benefits.”

Alternative Energy Sources: See Renewable Energy.

Alternative Fuel Vehicle (AFV): Motor vehicles that run on fuels other than petroleum–based fuels. As defined by the National Energy Policy Act EPAct, this excludes reformulated gasoline as an alternative fuel.

Ambient Air Temperature: Surrounding temperature, such as the outdoor air temperature around a building.

Ambient Air: outside air; any portion of the atmosphere not confined by walls and a roof

Ambient: The surrounding atmosphere; encompassing on all sides; the environment surrounding a body but undisturbed or unaffected by it.

American National Standards Institute (ANSI): is the national organization that coordinates development and maintenance of consensus standards and sets rules for fairness in their development. ANSI also represents the USA in developing international standards.

Amorphous silicon: An alloy of silica and hydrogen, with a disordered, noncrystalline internal atomic arrangement, that can be deposited in thin-film layers (a few micrometers in thickness) by a number of deposition methods to produce thin-film photovoltaic cells on glass, metal, or plastic substrates.

Ampere (AMP): The unit of measure that tells how much electricity flows through a conductor. It is like using cubic feet per second to measure the flow of water. For example, a 1,200 watt, 120–volt hair dryer pulls 10 amperes of electric current (watts divided by volts).

Ampere: The unit of measurement of electrical current produced in a circuit by 1 volt acting through a resistance of 1 Ohm.

Ancillary Services: Services that the Independent System Operator may develop, in cooperation with market participants, to ensure reliability and to support the transmission of energy from generation sites to customer loads. Such services may include: regulation, spinning reserve, non–spinning reserve, replacement reserve, voltage support, and black start.

Angle of Incidence: The angle that the sun's rays make with a line perpendicular to a surface. The angle of incidence determines the percentage of direct sunshine intercepted by a surface.

ANIMAL DANDER: Tiny scales of animal skin.

Animal Waste Conversion: Process of obtaining energy from animal wastes. This is a type of biomass energy.

Annual Fuel Utilization Efficiency (AFUE): A measure of heating efficiency, in consistent units, determined by applying the federal test method for furnaces. This value is intended to represent the ratio of heat transferred to the conditioned space by the fuel energy supplied over one year.

Annual Maximum Demand: The greatest of all demands of the electrical load which occurred during a prescribed interval in a calendar year.

Anthracite Coal: Hard coal, found deep in the earth. It burns very hot, with little flame. It usually has a heating value of 12,000–15,000 British thermal units per pound.

ANTIMICROBIAL: Agent that kills microbial growth. See "disinfectant," "sanitizer," and "sterilizer."

Apparent power: The product of the voltage (in volts) and the current (in amperes). It comprises both active and reactive power.  It is measured in “volt-amperes” and often expressed in “kilovolt-amperes” (kVA) or “megavolt-amperes” (MVA). 

Appliance efficiency index: A relative comparison of trends in new-model efficiencies for major appliances and energy-using equipment. The base year for relative comparisons was 1972 (1972=100). Efficiencies for each year were efficiencies of different model types that were weighted by their market shares.

Appliance efficiency standards: The National Appliance Energy Conservation Act of 1987 established minimum efficiency standards for major home appliances, including furnaces, central and room air conditioners, refrigerators, freezers, water heaters, dishwashers, and heat pumps. Most of the standards took effect in 1990. The standards for clothes washers, dishwashers, and ranges took effect in 1988, because they required only minor changes in product design, such as eliminating pilot lights and requiring cold water rinse options. The standards for central air conditioners and furnaces took effect in 1992, because it took longer to redesign these products. Appliance efficiency standards for refrigerators took effect in 1993.

Appliance Saturation: A percentage telling what proportion of all households in a given geographical area have a certain appliance.

Area Load: The total amount of electricity being used at a given point in time by all consumers in a utility's service territory.

Asbestos: A group of naturally occurring minerals that separate into long, thin fibers. Asbestos was used for many years to insulate and fireproof buildings. In the 1989 CBECS, information on asbestos in buildings was collected (Section R of the Buildings Questionnaire) for the U.S. Environmental Protection Agency (EPA) Asbestos treatment methods include removal, encapsulation or sealing, and enclosure behind a permanent barrier.

Ash: Non–organic, non–flammable substance left over after combustible material has been completely burned.

ASHRAE: Acronym for American Society of Heating, Refrigerating and Air–Conditioning Engineers.

Asphalt: A dark–brown–to–black cement–like material containing bitumens as the predominant constituents. It is obtained by petroleum processing.

Associated Energy Losses: See Electrical System Energy Losses.

Associated Gas: Natural gas that can be developed for commercial use, and which is found in contact with oil in naturally occurring underground formations.

Asthma: a medical condition characterized by abnormal restriction of breathing, especially in response to allergens or air contaminants.

ATgas: Synthetic gas produced by dissolving coal in a bath of molten iron. The process was developed by Applied Technology, Inc. Synthetic gas may be used as a substitute for natural gas in industrial and home uses.

Atom: The smallest unit of an element consisting of a dense positively charged nucleus (of protons and neutrons) orbited by negatively charged electrons.

Atomic Energy Commission: The independent civilian agency of the federal government with statutory responsibility to supervise and promote use of nuclear energy. Functions were taken over in 1974 by the Energy Research and Development Administration (now part of the U.S. Department of Energy) and the Nuclear Regulatory Commission.

Atomic Nucleus: The positively charged core of an atom.

Automatic set-back or clock thermostat: A thermostat that can be set to turn the heating/cooling system off and on at certain predetermined times.

Auxiliary Energy Subsystem: Equipment using conventional fuel to supplement the energy output of a solar system. This might be, for example, an oil–fueled generator that adds to the electrical output of a substitutes for the solar system during long overcast periods when there is not enough sunlight.

Auxiliary Equipment: Extra machinery needed to support the operation of a power plant or other large facility.

Average Demand: The energy demand in a given geographical area over a period of time. For example, the number of kilowatthours used in a 24–hour period, divided by 24, tells the average demand for that period.

Average Hydro: Rain, snow and runoff conditions that provide water for hydroelectric generation equal to the most commonly occurring levels. Average hydro usually is a mean indicating the levels experienced most often in a 104–year period.

Aviation Fuel: A category of fuel that includes aviation gasoline and jet fuel.

Aviation Gasoline: All special grades of gasoline for use in aviation reciprocating engines.

Avoided Costs (Regulatory): The amount of money that an electric utility would need to spend for the next increment of electric generation to produce or purchase elsewhere the power that it instead buys from a cogenerator or small–power producer. Federal law establishes broad guidelines for determining how much a qualifying facility gets paid for power sold to the utility.

Azimuth: The angular distance between true south and the point on the horizon directly below the sun. Typically used as an input for opaque surfaces and windows in computer programs for calculating the energy performance of buildings.
 

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