Glossary & Acronyms

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Air Changes per Hour (ACH): An expression of ventilation rates – the number of times in an hour that a home’s entire air volume is exchanged with outside air.

Air barrier: A layer of material resistant to air flow, usually in the form of polyolefin (i.e. Typar, Tyvek, and other housewraps). A material which is applied in conjunction with a building component (such as a wall, ceiling or sill plate) to prevent the movement of air through that component.

Air barrier system: The assembly of components used in building construction to create a plane of air tightness throughout the building envelope and to control air leakage.

Allergens: Any substance that initiate an overreaction of the immune system. Potential allergens include foods, drugs, and inhalants such as pollen or dust mite antigens. Repeated exposure to certain allergens can develop into chronic disease conditions.

Animal dander: Tiny scales of animal skin.

Asbestos: A mineral frequently used in residential and commercial insulation products that can easily separate into long, flexible fibers when disturbed. Asbestos fibers can become airborne due to deterioration, or damage during remodeling or removal projects. Health is endangered when asbestos fibers are inhaled or ingested. Long term risks from inhaled asbestos fibers include lung scarring. Lung cancer may develop many years after exposure to asbestos.

Blower Door: Diagnostic equipment consisting of a fan, removable panel and gauges used to measure and locate air leaks.

Blowing agent: A gas or a substance capable of producing a gas used in making foamed materials.

Btu: British Thermal Unit: The amount of energy that is required to raise 1 lb. of water up 1° F.

Btuh: A rate of energy transfer – can be expressed as Btu/hour.

Building envelope: The external elements walls, floor, ceiling, roof, windows and doors of a building that encloses conditioned space; the building shell.

Capillary action, Capillarity: The movement of liquid within a material against gravity as a result of surface tension.

CFC (Chlorofluorocarbon): Any of various halocarbon compounds consisting of carbon, hydrogen, chlorine, and fluorine.  Once used widely as aerosol propellants and refrigerants. Chlorofluorocarbons cause depletion of the atmospheric ozone layer.

Cellulose insulation: Insulation made from wood fiber, primarily recycled newspaper, treated with nontoxic chemicals to retard fire, mold and insects. Loose-fill cellulose can be blown into attic spaces or packed into wall cavities. Damp-spray cellulose is a damp mix of cellulose and adhesives that is sprayed into wall cavities before hanging drywall.

Clerestory: A window or row of windows placed high on a wall, often above the main roof line, used for introducing daylight into a room.

Combustion efficiency: A measure of useful heat extracted from a fuel source by an operating heating appliance. For example a furnace with a combustion efficiency of 60 percent converts 60 percent of the fuels energy content into useful heat. The rest is lost as exhaust gases.

Compact fluorescent light bulb (CFL): A fluorescent light bulb designed to replace regular incandescent bulbs. It is three to four times more energy efficient and lasts eight to ten times longer than an incandescent bulb.

Conditioned space: An enclosed space with conditioned air from a heating system, a cooling system, or both.

Conduction: Transmission of energy (heat /sound) through a material or from one material to another by direct contact. Materials with low rates of conductive heat transfer make good insulation.

Convection: Transmission of energy (heat /sound) from one place to another by movement of a fluid such as air or water.

Cotton insulation: Insulation made from post-industrial recycled cotton textile trimmings. Typically treated with a nontoxic fire retardant and sold as batts that are fit between framing studs.

Deconstruction: Disassembling rather than demolishing a building so that its contents can be reused.

Density: Determined by the weight expressed in pounds of a cubic foot of any material.

Dew point: The temperature at which a vapor begins to condense.

Diffusion: The movement of water vapor from regions of high relative humidity (RH) or pressure toward regions of lower RH driven by a higher to lower temperature differential.

Double-paned window: A window with two panes of glass separated by an air space. Compared to single-glazed windows, double-glazed windows significantly reduce heat and sound transmission. Some double-glazed windows contain a gas such as argon or krypton in the air gap to provide additional insulation.

Dual-flush toilet: A toilet designed to reduce water use, with two buttons or a specialized lever that allows the user to select a long or short flush.

Energy efficiency: Using less electricity or fuel than a conventional technology to perform the same task.

Energy Star: A program sponsored jointly by the U.S. Environmental Protection Agency and the U.S. Department of Energy that promotes energy-efficient products, homes and technologies for consumers and businesses. Energy Star qualified products and new homes are often ten to fifty percent more efficient than their conventional counterparts.

Exfiltration: Uncontrolled leakage of conditioned air from inside the home to the outside.

Flame retardant: A substance that is added to a polymer formulation to reduce or retard the tendency to burn.

Flame retarded: (Adj.); The property of a material to which flame-retardant has been added.

Flame spread: Unit of measure generated by a standard test for determining relative combustibility. The flame spread of a tested material is rated relative to red oak (flame spread = 100). ASTM = E84 is the test method used to determine the above.

Flammability: Relative ability of a material to support combustion as expressed by its flash point.

Fly ash: A waste product from coal-fired electric power plants that can be used as a substitute for Portland cement in some concrete mixtures.

Foam insulation: Spray foam insulation (also called foamed-in-place insulation) thoroughly fills ceilings and wall cavities, providing excellent insulation and effectively blocking air leakage. Rigid foam insulation comes in flat panels and can be used to insulate roofs, foundations, and wall surfaces. Some foam insulation is produced with hydrofluorocarbon (HFC) blowing agents that contain no chlorine and don’t damage the ozone layer, although all HFC’s are greenhouse gases.

Forest Stewardship Council (FSC): An international certification organization that has established voluntary environmental forest management standards. FSC accredits independent third-party organizations that monitor and certify the compliance of forestry operations with FSC standards. FSC-labeled wood products give consumers assurance that the wood comes from trees grown and harvested in an environmentally friendly, responsible manner.

Formaldehyde: A colorless, pungent gas used in many glues, adhesives, preservatives, and coatings. It also occurs naturally. Products and materials containing formaldehyde can offgas the chemical into the air. According to the U.S. Environmental Protection Agency, exposure to formaldehyde may cause allergic reactions, respiratory problems or cancer in humans.

Glazing: Transparent or translucent material, such as glass or plastic, that lets light into a building.

Grey water: Wastewater that does not contain sewage and can be reused for irrigation. Grey water typically comes from showers, sinks, and washing machines.

Heat gain: Heat from the sun, people, electric lights or appliances that cause the temperature in a space to rise.

Heat loss: Heat that is lost from a building by air leakage, conduction, and radiation. To maintain a steady interior temperature, heat losses must be offset by a combination of heat gains and heat contributed by a heating system.

Heat recovery ventilation (HRV) system: A mechanical ventilation system that recovers energy from exhausted indoor air and transfers it to incoming air. This system usually incorporates an air-to-air heat exchanger which transfers the heat from exhaust air to the incoming air or vice versa.

HCFC (Hydrochlorofluorocarbons): halogeneted compounds containing carbon, hydrogen, chlorine and fluorine. They have shorter atmospheric lifetimes than CFCs and deliver less reactive chlorine to the stratosphere where the ozone layer is found.

Humidistat: A humidity sensitive control device that signals the ventilation system to operate if the humidity goes above a preset limit.

Hydrophobic: Having no affinity for water; not compatible with water - “Water fearing”. Also, having the quality preventing growth of mold and mildew.

Indoor air quality (IAQ): The level of air pollutants inside a building. Indoor air pollution sources include tobacco and wood smoke; certain building materials and furnishings; certain cleaning, maintenance, and personal care products; dust mites; pet dander; mold; radon; pesticides; and outdoor pollution. Inadequate ventilation and high humidity levels can also contribute to indoor air quality problems.

Infiltration: Uncontrolled leakage of air into a building through cracks around doors, windows, electrical outlets and at structural joints. Uncontrolled leakage of conditioned air from the outside of the home to the inside.

Insulation: Materials with low thermal conductivity characteristics that are used to slow the rate of heat transfer.

Isocyanate (typically MDI): One of a group of neutral derivatives of primary amines (R-N=C=O) groups. An essential component (A) of polyurethane foam chemistry.

Kilowatt (kW): A unit of electrical power equal to 1,000 watts.

LEED Green Building rating System: A voluntary, consensus-based national standard for high-performance sustainable buildings. Developed and administered by the U.S. Green Building Council. LEED is an acronym for Leadership In Energy and Environmental Design.

Material Safety Data Sheet (MSDS): A standard formatted information sheet, prepared by a material manufacturer, describing the potential hazards, some physical properties, and procedures for safe use of a material.

Mold: Fungal growths often resulting in deterioration of organic materials, especially under damp conditions.

Offgas: The release of vapors from a material through the process of evaporation or chemical decomposition. Many building products, furnishings, floor and wall coverings and other products brought into the home offgas formaldehyde, volatile organic compounds (VOC’s) or other potentially troublesome chemicals.

Organic: Compounds containing carbon.

Overspray: (1) Airborne particle loss of polyurethane foam in spray application; (2) Undesirable depositions of airborne spray loss.

Passive solar design: A building component specifically designed to collect and store the sun’s heat, and release that heat into the interior spaces to help warm the rooms naturally. Depending on the design and climate, passive solar heating can be the sole source of heat for the building or can be supplemented with a heating system.

Perm: A unit of water vapor transmission defined as 1 grain of water vapor per square foot per hour per inch of mercury pressure difference (1 inch mercury = 0.49 psi). Metric unit of measure is ng/m2 s Pa. 1 perm = 55 ng/m2 s Pa.

Permeability: The time rate of water vapor transmission through unit area of a material of unit thickness induced by unit vapor pressure difference between two specific surfaces, under specified temperature and humidity conditions. (add units like above)

pH: A measure of acidity/alkalinity of aqueous mixtures. A measure of pH 7 is neutral, lower is more acidic, higher is more alkaline.

Photovoltaic (PV) system: Devices that generate electricity from sunlight.

Pressurized fog testing: Done in conjunction with a blower door test, pressurized fog tests visually identify air leaks in a building’s envelope. The test is usually done when temperature and weather conditions make an infrared scan difficult.

Product data sheet: A listing of all the general characteristics and components of a chemical or product. (See MSDS).

PSI: Pounds per square inch.

Radiant barrier: A material installed in buildings to reduce summer heat gain (and, to a lesser extent, winter heat loss). Radiant barrier products typically consist of a thin sheet of reflective material such as aluminum, attached to a substrate such as plywood, oriented strand board or kraft paper. The product is typically installed in a home’s attic to reduce the transfer of heat from the roof to the home.

Radiation: Transfer of energy (heat/sound) from one object to another through an intermediate space. Only the object receiving the radiation, not the space, is heated. The heat is in the form of low-frequency, infrared, invisible, light energy, transferring from a “warm” object to a “cold” object. It is known as the “black body effect”.

Relative humidity: The ratio expressed as a percentage of the amount of moisture air actually contains to the maximum amount it could contain at that temperature.

Renewable energy: Energy generated from replenishable resources, such as sunlight, wind, and agricultural products.

Resin: Component B in polyurethane foam chemistry. This component is mixed with the A component to form foam insulation. (See Isocyanate)

Retrofit: The modification of an existing building or facility to include new systems or components.

R-Value: A measure of a material’s resistance to the passage of heat through it. The higher the R-value, the more effective the material is as insulation.

SEER: Seasonal Energy Efficiency Ratio. Indicates an air conditioner’s energy efficiency. The higher the SEER, the more efficient the air conditioner.

Standard testing: Laboratory test methodology for determining relative properties of materials at specific conditions.

SUPERGREEN™ foam: A rigid plastic polyurethane foam that uses zero ozone depletion Freon (HFC-134a) as the blowing agent.

Superinsulation: The word was coined during the energy crisis of the 70’s and is an approach to solving thermal envelope problems. Superinsulation is usually, but not always, one of the several polyurethane foam systems.

Sustainability: Meeting the needs of the present without compromising the ability of future generations to meet their own needs (as defined by the World Commission on Environment and Development).

Tankless water heater: A water heater that saves energy by heating water as it is needed, rather than storing hot water in a tank. Also known as an instantaneous, flash, or demand water heater.

Thermostat: “Temperature sensitive” control device that signals a heating or cooling system to operate if the temperature in a conditioned space reaches a preset limit.

Thermal barrier: A material applied over foam insulation designed to slow the temperature rise of the foam during a fire situation, thus delaying its involvement in the fire.

Thermal bridge: A thermally conductive material, which penetrates or bypasses an insulation system, such as a metal fastener or stud.

Thermal mass: The ability of a material to absorb and retain heat. Materials with a high thermal mass, such as rocks, earth and concrete, have the capacity to absorb heat during the day and release it when temperatures cool off.

Thermal resistance (R): An index of a material’s resistance to heat flow. (See R-Value and RSI)

Thermal shock: A building materials reaction to rapid changes in temperature, usually associated with the curing process.

Thermography (Infrared scan): A building energy diagnostic technique using an infrared camera for locating areas of temperature differential or air leakage in a building. Often used in conjunction with pressurization or depressurization.

Title 24: The State of California’s building code, which includes regulations for building energy efficiency practices.

U-Value: Overall thermal conductance. U-value is equal to the inverse of the sum of the R-values in a system (U = 1 /R total).

Vapor barrier: A layer of moisture resistant material which controls moisture diffusion (defined as less than 1 perm in typical building environments) to prevent moisture migration into building cavities.

Ventilation: The process of bringing outside air into an indoor space, by natural or mechanical means.

Viscosity: The thickness or resistance to flow of a liquid. Viscosity generally decreases as temperature increases; application temperatures of polyurethane foam components are specified in part, to control viscosity at the dispensing gun.

Volatile Organic Compounds (VOC): Any compound containing carbon and hydrogen or containing carbon and hydrogen in combination with other elements.

Whole-house fan: A powerful fan mounted in a ceiling opening, used to pull air through the home and exhaust it out the attic and through the roof vents. It provides air circulation and cooling in climates where days are warm and nights are cooler, and can often reduce or eliminate the need for air conditioning. A whole-house fan is typically used at night to pull cooler outside air into the home through open windows, and to vent warm air through the attic and roof.

Wind turbine: A machine that converts wind into electricity. Also known as a wind generator.



ABAA: Air Barrier Association of America

AIA: American Institute Of Architects

AISI: American Iron & Steel Institute

ALA: American Lung Association

ANSI: American National Standards Institute

ASHRAE: American Society for Heating, Refrigeration and Air Conditioning Engineers

ASTM: American Society for Testing and Materials

BETEC: Building Environment & Thermal Envelope Council

BOCA: Building Officials and Code Administrators

CABO (ICC): Conference of American Building Officials (International Code Council)

CBPCA: California Building Performance Contractors Association

CCMC: Canadian Construction Materials Centre

CSA: Canadian Standards Association

DOE: U.S. Department of Energy

EEM: Energy Efficient Mortgage

EPA: Environmental Protection Association

EEBA: Energy Efficient Builders Association

EREC: Energy Efficiency and Renewable Energy Clearing House (DOE program)

FSC: Forest Stewardship Council

IAQ: Indoor Air Quality

IBC: International Building Code

ICBO: International Conference of Building Officials

IR: Infrared

HERS: Home Energy Rating Services

HVAC: Heating, Ventilating and Air Conditioning

LEED: Leadership in Energy and Environmental Design

NAHB: National Association of Home Builders

NAHBRC: NAHB Research Center

NBC: National Building Code of Canada

NEAT: Novel Environmental Advanced Technology

NER: National Evaluation Report

NIBS: National Institute of Building Sciences

NIST: National Institute of Standards and Technology

NRC: National Research Council of Canada

ORNL: Oak Ridge National Laboratories

SBCCI: Southern Building Codes Congress International

SPFA: Spray Polyurethane Foam Alliance

UBC: Uniform Building Code

UL: Underwriter’s Laboratories

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