scope:

This standard applies to dwelling units in residential occupancies in which the occupants are nontransient.

This standard considers chemical, physical, and biological contaminants that can affect air quality. Thermal comfort requirements are not included in this standard.

Informative Note: See ANSI/ASHRAE Standard 55, Thermal Environmental Conditions for Human Occupancy, for thermal comfort requirements.

While acceptable IAQ is the goal of this standard, it will not necessarily be achieved even if all requirements are met

a. because of the diversity of sources and contaminants in indoor air and the range of susceptibility in the population;

b. because of the many other factors that may affect occupant perception and acceptance of IAQ, such as air temperature, humidity, noise, lighting, and psychological stress;

c. if the ambient air is unacceptable and this air is brought into the building without first being cleaned (ambient outdoor air cleaning is not required by this standard);

d. if the system or systems are not operated and maintained as designed; or

e. when high-polluting events occur.

PURPOSE

This standard defines the roles and minimum requirements for mechanical and natural ventilation systems and the building envelope intended to provide acceptable indoor air quality (IAQ) in residential buildings.