ABS

Acrylonitrile butadiene styrene: a lightweight, black, durable plastic used for piping due to its high strength. It is recyclable, but not many recycling centers accept it. It needs to be shielded from the sun as it is not completely UV stable. It is better overall than cast iron and PVC for risks for health and environment.

Absorption chiller

A water chilling process in which cooling is accomplished by the evaporation of a fluid (usually water), which is then absorbed by a different solution (usually lithium bromide), then evaporated under heat and pressure. The fluid is then condensed with the heat of condensation rejected through a cooling tower.

Accessory dwelling unit (ADU) (also granny flat or in-law apartment)

A small, self-contained residential unit built on the same lot as an existing single-family home (either outside the home or contained within it). These resourceful, efficient tiny houses allow for increased lot density, an income source and multi-generational family flexibility.

ACH

Air changes per hour: ACH is a measure of the rate at which interior air is replaced with outside air. For example, an ACH of 0.5 means that all the air in the building will change out in two hours.

Acid leachate

Water that has become acidic after seepage through landfills; potentially very damaging to fish habitats and drinking water supplies.

Action level

A term used by the US EPA to identify the level of indoor radon at which remedial action is recommended.

Active system

Traditional heating, cooling and ventilating systems which use mechanical means to artificially condition (cool, heat, ventilate) the air supply in buildings, and draw power for these mechanical processes from electricity or gas.

Adaptability

Design strategy that allows for multiple future uses in a space as needs evolve and change. Adaptable design is considered a sustainable building strategy as it reduces the need to resort to major renovations or tearing down a structure to meet future needs.

Adaptive reuse

Rehabilitation 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 (see Historic preservation).

Adobe

Mud bricks reinforced with straw. Used particularly in Latin America and southwestern USA, adobe produces a distinctive architectural style based on organic forms, a smooth finish, and a minimum of window openings.

Advanced framing

Refers to a variety of framing techniques designed to reduce the amount of lumber used and waste generated in the construction of a wood-framed structure while increasing space available for insulation.

Aerator

A faucet aerator mixes air with a flow of water and is used to oxygenate water, to smooth the flow of water and to reduce splashing.

Affordable housing

Housing that is affordable for its target market. This means what the householder pays. Housing quality and housing affordability must continue over the housing’s expected useful life (typically 30-50+ years). This implies that the housing must take in enough cash flow to cover its expenditures, including capital expenditures. The housing must be market-competitive quality that can blend in to its neighborhood. This excludes substandard locations, configurations, construction, and maintenance. 

AFUE

Annual fuel utilization efficiency: ratio of annual output energy to annual input energy. Measure of efficiency of gas furnaces and boilers. The higher the percentage the greater the efficiency of the appliance. Standard efficiencies run in the mid-70% to 82% ranges. Higher efficiency furnaces run 90+ %AFUE.

AFV

Alternative fuel vehicle: a vehicle powered by a fuel other than gasoline.

Aging-in-place

Being able to remain in one's present residence and respond to changing needs as one ages.

Agricultural fiber

Agricultural fibers (i.e., cotton) used as insulation materials.

Agricultural waste

Materials left over from agricultural processes (e.g., wheat stalks, shell hulls, etc.). Some of these materials are finding new applications as building materials and finishes. Examples include structural sheathing and particleboard alternatives made from wheat, rye and other grain stalks, and panels made from sunflower seed hulls.

Agrifiber board

A composite panel product derived from recovered agricultural waste fiber from sources including, but not limited to, cereal straw, sugarcane bagasse, sunflower husk, walnut shells, coconut husks, and agricultural prunings.  The raw fibers are processed and mixed with resins to produce panel products with characteristics similar to those derived from wood fiber. 

AHU

Air Handling Unit: equipment that includes a fan or blower, heating and/or cooling coils, regulator controls, condensate drain pans, and air filters.

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 Quality Construction Management Plan

A systematic plan for addressing construction practices that can impact air quality during construction and continuing on to occupation.

Air retarder/ barrier

A set of materials installed around a building frame to prevent or reduce air infiltration. Installed as an energy-efficiency measure to reduce air leaks while reducing water vapor transpiration into cavities. Not to be confused with a vapor retarder/vapor barrier.

Air-to-air heat exchangers

(See Heat recovery ventilator).

Albedo

Ratio of reflected light to the total amount of light falling on a surface. In hot climates, it is desirable to use roofing materials with a high albedo.

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 fuels

Substitutes for traditional liquid, oil-derived motor vehicle fuels like gasoline and diesel. Includes mixtures of alcohol-based fuels with gasoline, methanol, ethanol, compressed natural gas, and others.

Alternative refueling station

Location that provides the service of refueling an alternative fuel vehicle (i.e. electricity, compressed natural gas). Providing access to alternative fuels with a refueling station is considered a sustainable building strategy in that it encourages the use of alternative fuels and the vehicles that use them.

ANSI

American National Standards Institute: as the U.S. standards and conformity assessment system, the non-profit ANSI empowers its members and constituents to strengthen the U.S. marketplace position in the global economy while helping to assure the safety and health of consumers and the protection of the environment.

Appraisal value

An estimate of the market value of property substantiated by various analyses, usually by comparison with similar properties.

Architecture 2030

A non-profit, non-partisan and independent organization, established in response to the global-warming crisis by architect Edward Mazria in 2002. 2030’s mission is to rapidly transform the US and global building sector from the major contributor of greenhouse gas emissions to a central part of the solution to the global-warming crisis. Their goal is to achieve a dramatic reduction in the global-warming-causing greenhouse gas (GHG) emissions of the Building Sector by changing the way buildings and developments are planned, designed and constructed. They have issued the 2030 Challenge for all new buildings to be carbon-neutral in 2030 (using no fossil fuel greenhouse gas-emitting energy to operate).

Argon gas

A colorless and odorless gas used to fill the airspace between insulating Low E glass. The addition of argon greatly increases the insulating performance.

Array

Several photovoltaic (PV) panels or thermal panels (for hot water) linked together in a series.

Asbestos

A mineral fiber that has been commonly used in many building construction materials for insulation and as a fire-retardant. Invisible fibers of asbestos can be inhaled and have been connected to lung diseases and cancer.

ASHRAE

American Society of Heating, Refrigeration and Air Conditioning Engineers: the national organization responsible for setting standards for heating, cooling and ventilation for buildings and equipment.

ASTM

American Society for Testing and Materials: an international standards developing organization that develops and publishes voluntary technical standards for a wide range of materials, products, systems, and services. It publishes The Annual Book of ASTM Standards.