The following information is from the Minnesota Department of Commerce:

Air Barrier: Any part of the building shell that offers resistance to air leakage between indoors and outdoors. Air barriers can be composed of many combinations of materials including properly installed drywall, plastic sheeting, or woven exterior house-wrap. Also known as an air flow retarder.

Air Exchange: The total building air exchanged with the out-doors through air leakage and intentional ventilation.

Air Sealing: A weatherization term or description which deals with activities that help reduce air bypasses or air leakage in a home, measured by blower door readings. “Major air sealing” includes sealing bypasses and other large openings between the heated and unheated spaces. “Minor air sealing” includes sealing small air openings with materials such as caulk, weather stripping and sash locks.

Air Tightness: The relationship between the exchange of inside air in a dwelling, being replaced at a standardized rate of exchange, with fresh out-side air measured in cubic feet per minute (CFM).

Attic Bypasses: Attic bypasses are a major source of air leaks. Bypasses are hidden air passageways that lead from the heated space into the attic. Because warm air rises, it continuously moves up these passageways and escapes into the attic during cold weather.

Blower Door Testing: Tests or measurements to determine the air leakage in a dwelling, overall duct leakage in heating distribution ductwork and pinpointing problem areas which are performed using the blower door.

Boiler: A water-based heating system, which circulates hot water or steam through a pipe system.

CO Levels: Carbon monoxide measurements. This specific byproduct of combustion is dangerous, or even deadly, if found in high concentrations inside the living spaces of dwellings. It is measured in parts per million (PPM) and there are set safety standards for various levels.

Combustion Air: Air that combines with fuel in the combustion process. Refers also to the supply of outdoor air that supports this process.

Combustion Analyzer: A device used to measure the steady-state efficiency of combustion heating units.

Combustion Test: A measurement performed to determine, among other things, the efficiency at which a heating appliance is operating.

Consumption: Data pertaining to primary and secondary heating and non-heating electric costs. Also, units, such as gallons of oil or kilowatt-hours (kWh), used by a household or dwelling for a specified period of time.

Draft Diverter: A device located in the flue of gas appliances to moderate draft and direct backdrafts away from an appliance.

Energy Audit: The process where a trained staff person assesses and documents the energy conservation needs of a dwelling, including furnace safety and efficiency testing, and all cost effective weatherization measures.

Furnace Test: A procedure for measuring the safety or fuel efficiency of furnaces or boilers.

Heat Loss: The amount of heat that escapes through the building shell during a measured period of time.

High Consumption: A specific measurement for a dwelling that uses higher than average fuel, electric or heating costs. An ART calculation of seven or higher, is often used as a measure of high primary heat consumption.

High Efficiency: A heating system that utilizes 90% of the available heat energy in a fuel source.

House Pressure: The difference in air pressure between the indoor air space and outside, measured by a manometer.

Humidity: Water vapor that is absorbed in the air.

Humidity levels: A sling psychrometer or digital gauge is used to check humidity levels in the home during an energy audit.

Insulation: A weatherization term used to describe materials used because of their high thermal resistance. Most insulation material in the weatherization program is blown into attic spaces or wall cavities. Properly installed “dense pack” insulation may slow air infiltration and convection within building cavities.

Mechanical Systems: A dwelling unit’s home air heating and/or water heating designs and their distribution systems. The primary components of the mechanical system include those appliances (and their fuel supply, control and distribution systems) which heat the dwelling and provide hot water for domestic use.

Pascal: A unit of measure for air or gas pressure. 256 pascals equal one inch of water column (IWC). One IWC = .4 pascal.

Pressure Balancing: To equalize house or duct pressure by adjusting air flow in supply and return ducts. Used on dwellings with forced air heating systems.

Pressure Diagnostics: A tool used to determine the size of air leaks or bypasses as well as the effectiveness of contractor’s air sealing techniques. It measures air pressure differences between outside air, the inside of a dwelling unit’s thermal envelope, and any intermediary zones.

R-Value: A measurement of thermal resistance, used to assess the effectiveness of insulating materials.

Red Tagged: A notification of an immediate hazard or safety issue related to a furnace or boiler. It always results in the unit being shut-off or having its energy source (usually gas or propane) being locked or closed to prevent any operation of the heating plant. A “yellow tagged” furnace can still be operated but has identified operation problems which require attention or repair.

Sealed Combustion: A heating appliance system that acquires all its combustion air through a sealed passage to the outside. Combustion takes place in a sealed combustion chamber. All combustion products are vented to the outside through a separate sealed vent.

Weatherization: Conservation activities applied to a dwelling which help to conserve heat, maintain temperature and provide a safe and healthy living environment.