Indoor air quality problem in which potentially dangerous combustion gases escape into
the house instead of going up the chimney.

Practice of heating a building prior to occupancy (generally to about 100°F) to accelerate VOC emissions from furniture and materials. This practice is unproven and is not recommended.

Balance point is the outdoor temperature at which the amount of heating provided by an air source heat pump just equals the amount of heat lost from the house. Below this point, supplementary heat (typically inefficient electric resistance heat or “strip heat”) is required. Typical balance point temperatures are in the range of 27 - 35 degrees Fahrenheit.

Mechanical ventilation system in which separate, balanced fans exhaust stale indoor air and bring in fresh outdoor air in equal amounts; often includes heat recovery or heat and moisture recovery (see heat-recovery ventilator and energy-recovery ventilator).

Insulation, usually of fiberglass or mineral wool and often faced with paper, typically installed between studs in walls and between joists in ceiling cavities. Correct installation is crucial to performance.

Literally “Building Biology,” a term coined in Germany to describe the use of holistic, healthy-building principles—particularly those focused on indoor air quality and electromagnetic fields—to safeguard the wellbeing of a building’s occupants.

Glue used in manufactured wood products, such as medium-density fiberboard (MDF), particleboard, and engineered lumber. Some binders are made with formaldehyde. See urea-formaldehyde binder and methyl diisocyanate (MDI) binder.

Material made from living matter, such as agricultural crops. Biobased materials are usually biodegradable.

Chemicals toxic to microorganisms. Biocides, which include pesticides and antimicrobial agents, are used in paint, building materials, and floor coverings to kill bacteria, mold spores, insects, etc.

Organic waste that can be converted to usable forms of energy such as heat or electricity, or crops grown specifically for that purpose.

Practice of imitating nature in the design and/or production of buildings, systems, or products.

Potentially contaminated wastewater from the toilet, kitchen sink, or other sources. Black water should not be reused without going through a complete treatment system.

Test used to determine a home’s airtightness: a powerful fan is mounted in an exterior door opening and used to pressurize or depressurize the house. By measuring the force needed to maintain a certain pressure difference, a measure of the home’s airtightness can be determined. Operating the blower door also exaggerates air leakage and permits a weatherization contractor to find and seal those leakage areas.

Boron-containing chemical that provides fire resistance to materials such as cellulose insulation and provides decay and termite resistance to wood products. Borate is derived from the mineral borax and is benign, compared with most other wood treatments.

British thermal unit, the amount of heat required to raise one pound of water (about a pint) one degree Fahrenheit in temperature—about the heat content of one wooden kitchen match. One Btu is equivalent to 0.293 watt-hours or 1,055 joules.

Professional, nonprofit membership organization that promotes healthy, energy- and resource-efficient buildings in California. It was formed in 2005 in a merger of Bay Area Build It Green and The Green Resource Center of Berkeley. Headquartered in Berkeley, Build It Green offers professional training and other support services, maintains a regional green products database, and administers the Green Point Rated home certification program.

A U.S. Department of Energy (DOE) program to promote the construction of “better than Energy Star” homes. A home must have a maximum HERS rating of 70 to meet Builders Challenge requirements.

Exterior components of a house that provide protection from colder (and warmer) outdoor temperatures and precipitation; includes the house foundation, framed exterior walls, roof or ceiling, and insulation, and air sealing materials.

Typically referring to Grade D building paper, this product is an asphalt-impregnated kraft paper that looks a lot like a lightweight asphalt felt. The Grade D designation has come to mean that the building paper passes ASTM D779 (minimum 10-minute rating with the “boat test”) and different products are called out as “30-minute” or even “60-minute” based on D779 results. At times confused with roofing felt, roofing felts and building paper differ in two ways: felts are made of recycled-content paper, building papers of virgin paper; felts are made of a heavier stock paper; building papers a lighter stock. See also roofing felt.

Environmental building program of the Master Builders Association of King and Snohomish counties in Washington state. Offers four rating systems that cover single family homes, remodels, multifamily dwellings, and communities; ratings are either self-certified or verified by a third party, depending on the level of certification.

Joint effort of the Home Builders Association of Metro Denver, government, utilities, and product manufacturers to promote green building through training opportunities, technical support, and a Built Green designation for homes constructed using the program’s guidelines.