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 ALL
A/C
See "Air Conditioning" and "Heating Ventilation and Air Conditioning."
Abatement
Reduction of the degree or intensity of, or elimination of pollution.
Abridged Life Cycle Assessment (ALCA)
A simplified methodology to evaluate the environmental effects of a product or activity holistically, by analyzing the most significant environmental impacts in the life cycle of a particular product, process, or activity. The abridged life cycle assessment consists of three complimentary components, restricted inventory analysis, abridged impact assessment, and improvement analysis, together with an integrative procedure known as "Scoping."
Absolute Pressure
The sum of the gauge pressure reading and atmospheric pressure. See also "PSIA."
Absorption
Process by which a substance or particle is drawn into the structure of another.
ACE
See "Air Change Effectiveness."
Acetone
A colorless, volatile, extremely flammable liquid ketone, CH3COCH3, widely used as an organic solvent.
ACH
See "Air Changes per Hour."
Acid Deposition
The deposition of acid constituents to a surface. This occurs not only through precipitation, but also by the deposition of atmospheric particulate matter and the incorporation of soluble gases.
Acid Rain
The precipitation of dilute solutions of strong mineral acids, formed by the mixing in the atmosphere of various industrial pollutants (primarily sulfur dioxide and nitrogen oxides) with naturally occurring oxygen and water vapor.
Acrylics
A family of plastics used for fibers, rigid sheets and paints.
Active Diffuser
An air supply outlet with a local fan to deliver air from the plenum through the diffuser into the conditioned space.
Active Solar Techniques
Mechanisms, such as flat-plate collectors, which are designed to actively collect the energy of sunlight and use it; for example, to heat a building or to heat water.
Active System
A traditional HVAC system that uses mechanical means to artificially condition (cool, heat, ventilate) the air supply in a building and that draws power for these processes from electricity or gas.
Acute Exposure
A single exposure to a toxic substance that may result in severe biological harm or death. Acute exposures are usually characterized as lasting no longer than a day, as compared to longer, continuing exposure over a period of time.
Acute Toxicity
The ability of a substance to cause severe biological harm or death soon after a single exposure or dose. Also, any poisonous effect that results from a single short-term exposure to a toxic substance.
Adaptive Reuse
Renovation of a building or site to include elements that allow a particular use or uses to occupy a space that originally was intended for a different use.
Adsorbent
Material that is capable of the binding and collection of substances or particles on its surface without chemically altering them.
Adsorption
Removal of a pollutant from air or water by collecting the pollutant on the surface of a solid material.
Advanced Treatment
A level of wastewater treatment more stringent than secondary treatment; requires an 85% reduction in conventional pollutant concentration or a significant reduction in non-conventional pollutants. Sometimes called tertiary treatment.
AEE (Association of Energy Engineers)
A trade organization for certification and information on energy efficiency, utility deregulation, facility management, plant engineering, and environmental compliance.
Aeration
Exposing water to the air; often results in the release into the atmosphere of gaseous impurities found in polluted water.
Aerobic Treatment
Process by which microbes decompose complex organic compounds in the presence of oxygen and use the liberated energy for reproduction and growth.
Aerosol
Suspended droplets of liquid or liquid dispersions in air.
AFUE
See "Annual Fuel Utilization Efficiency."
Agenda 21
A comprehensive blueprint for global action drafted by the 172 governments present at the 1992 Earth Summit organized by the United Nations in Rio de Janeiro, Brazil.
Agricultural Bi-products
Products developed in agriculture but are not primary products. These are often converted into building materials, such as straw used in wall panels or entire bales used as building blocks.
Agricultural Fibers
Natural fibers, such as cotton, often used as insulation materials.
AHU
See "Air Handling Unit."
Air Barrier
Material installed around a building frame to reduce the infiltration of air into the interior.
Air Change
The replacement of air contained within a room with an equivalent volume of fresh air.
Air Change Effectiveness (ACE)
The ability of an air distribution system to provide ventilation (outside) air at the breathing zone (where occupants breathe). It is defined as the age of air that would occur throughout the space if the air was perfectly mixed, divided by the average age of air where occupants breathe.
Air Changes Per Hour (ACH)
Number of times per hour a volume of air, equivalent to the volume of space, enters that space.
Air Cleaner
A filtering device that actively removes impurities from the air.
Air Conditioning (A/C)
A system that extracts heat from an area using a refrigeration cycle. A complete system of heating, ventilation, and air conditioning is referred to as HVAC. See "Heating, Ventilating and Air Conditioning."
Air Conditioning and Refrigeration Institute (ARI)
A trade association (representing manufacturers of more than 90 percent of the air conditioning and commercial refrigeration equipment installed in North America) that develops standards for and certifies the performance of these products.
Air Consumption
The volume of air required to operate a pneumatic device.
Air Exchange Rate
The rate at which outside air replaces indoor air in a given space. Also see "Air Changes Per Hour."
Air Flow
The movement of air within a room, duct, or plenum.
Air Flow Sensor
A device that measures air velocity (via differential pressure) inside a duct.
Air Handling Unit (AHU)
Equipment that includes a fan or blower, heating and/or cooling coils, regulator controls, condensate drain pans, and air filters.
Air Inlet
Apertures (grilles, diffusers, or louvered openings) through which air is intentionally drawn from a conditioned space.
Air Outlet
Apertures (grilles, diffusers, or louvered openings) through which air is intentionally delivered to a conditioned space.
Air Plenum
Any space used to convey air in a building, furnace or structure. The space above a suspended ceiling is often used as an air plenum.
Air Pollutant
Any substance in air that could, in high enough concentration, harm man, other animals, vegetation or material. Pollutants may include almost any natural or artificial composition of matter capable of being airborne. They may be in the form of solid particles, liquid droplets, gases or any combination thereof. Air pollutants are often grouped in categories for ease in classification. Some of these categories are solids, sulfur compounds, volatile organic chemicals, particulate matter, nitrogen compounds, oxygen compounds, halogen compounds, radioactive compounds and odors.
Air Pollution
The presence of contaminants or pollutant substances in the air that interfere with human health or welfare, or produce other harmful environmental effects.
Air Quality Standards
The level of pollutants prescribed by regulations that are not to be exceeded during a given time in a defined area.
Air Retarder
See "Air Barrier."
Air Supply Volume
The volume of supply air flowing through a cross-sectional plane of a duct per unit time, found by multiplying air velocity by the cross-sectional area of the duct.
Air Toxics
Any air pollutant for which a National Ambient Air Quality Standard (NAAQS) does not exist that may reasonably be anticipated to cause serious or irreversible chronic or acute health effects in humans.
Airborne Particulates
Total suspended particulate matter found in the atmosphere as solid particles or liquid droplets. Chemical composition of particulates varies widely, depending on location and time of year. Sources of airborne particulates include dust, emissions from industrial processes, combustion products from the burning of wood and coal, combustion products associated with motor vehicle or non-road engine exhausts, and reactions to gases in the atmosphere.
Albedo
A reflective property of a surface.
Allergen
A substance (also known as an antigen) that can trigger immune responses resulting in an allergic reaction.
Alternative Energy
Energy from a source other than the conventional fossil-fuel sources of oil, natural gas and coal (i.e., wind, running water, the sun). Also referred to as "alternative fuel."
Alternative Energy Sources
Energy sources, which can be substituted for fossil fuels, nuclear power, and large-scale hydroelectric power; e.g., solar, wind, geothermal, biomass.
Ambient Air
The surrounding air.
Ambient Temperature
Temperature of the surrounding air or other medium.
American National Standards Institute
See "ANSI."
American Society of Heating, Refrigerating and Air-Conditioning Engineers
See "ASHRAE."
Annual Fuel Utilization Efficiency (AFUE)
(AFUE) Seasonal efficiency of a gas-fired furnace or boiler. Takes into account cyclic operation. The higher the number, the more efficient the heating equipment.
Annual Fuel Utilization Efficiency (AFUE)
A measure of efficiency for gas furnaces and boilers, the ratio of annual output energy to annual input energy.
ANSI (American National Standards Institute)
A private nonprofit organization overseeing the development of voluntary consenses standards for products, services, processes, systems, and personnel in the United States. The organization also coordinates U.S. standards with international standards so that American products can be used worldwide.
Anthropogenic
Derived from human activities.
Antigen
See "Allergen."
Antimicrobial
An agent that kills microbes.
Aquifer
Any underground water-bearing rock formation or group of formations, that supplies ground water, wells, or springs.
ARI
See "Air Conditioning and Refrigeration Institute."
Asbestos
A mineral fiber that can pollute air or water and cause cancer or asbestosis when inhaled. The EPA has banned or severely restricted its use in manufacturing and construction.
Asbestos Abatement
Procedures to control fiber release from asbestos-containing materials in a building or to remove them entirely, including removal, encapsulation, repair, enclosure, encasement, and operations and maintenance programs.
ASHRAE
American Society of Heating, Refrigeration and Air Conditioning Engineers. A world-wide organization that promotes the arts and sciences of heating, ventilation, air conditioning, and refrigeration and that publishes standards. Particularly important in relationship to green building construction is ASHRAE 90.1 Energy Standard for Buildings Except Low-Rise Residential Buildings, a code setting requirements for energy efficiency and methods of determining compliance.
ASHRAE Standard 62
Ventilation for Acceptable Indoor Air Quality. Details two methods for compliance: Ventilation Rate Procedure and the Indoor Air Quality Procedure. Rapidly becoming the standard of care for building ventilation and indoor air quality.
Atmospheric Pressure
The pressure due to the weight of the atmosphere (14.7 PSI at sea level).
Attainment Area
An area considered to have air quality as good as or better than the national ambient air quality standards as defined in the Clean Air Act. An area may be an attainment area for one pollutant and a non-attainment area for others.
