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, [..]

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

A weatherization

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 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 a [..]

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.

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

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 mil [..]

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

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