Residential Mechanical Ventilation Systems

1.1 This Standard defines the requirements for performance, installation and application, and performance verification of mechanical ventilation systems. This Standard applies to systems that are capable of providing minimum controlled rates of ventilation air to the habitable spaces of those single-family dwellings that (a) fall within the Scope of Part 9 of the National Building Code of Canada; and (b) are self-contained with respect to heating, ventilation, and air conditioning.

1.2 This Standard also applies to the installation requirements for ventilation components such as supply and exhaust ventilation fans and associated equipment, including bathroom and kitchen exhaust fans and range hoods, with or without ducts, intended for operation in dwelling units referred to in Clause 1.1, whether or not a part of a ventilation system conforming to this Standard. (See Appendix B.)

1.3 This Standard also applies to the installation requirements for self-contained ducted heat recovery ventilators intended for operation in dwelling units referred to in Clause 1.1, whether or not they constitute a part of a ventilation system conforming to this Standard. The applicable heat recovery ventilators have a maximum rated capacity of not less than 25 L/s and not more than 200 L/s. (See Appendix B.)

1.4 This Standard does not apply to the installation of rec irculating forced-air heating and air conditioning systems that are not used for ventilation, but does apply to combined or integrated heating, ventilating and air conditioning systems intended t o provide ventilation air in accordance with this Standard.

1.5 This Standard includes provisions for equipment selection and installation, system installation, and information to be provided to the purchaser.

1.6 The rates of ventilation and exhaust air specified in this Standard apply to the minimum capability of the system. This Standard does not mandate the way in which the occupant operates the system. The rates in operation depend on the preference of the occupants.

1.7 The amounts of ventilation and exhaust air specified in this Standard are intended to deal with contaminants at the rates of generation normally encountered in residential dwellings. Acceptable indoor air quality also requires that the rate of contaminant generation be controlled.

1.8 In establishing the dwelling unit pressure design requirements (Clause 6), the house is considered as a "system" that has ventilation subsystems which move air into and out of a building while taking into account the leakage characteristics of the envelope, climatic conditions, the operation of exhaust devices not part of the ventilation system, and the venting characteristics of vented combustion appliances, including fireplaces.

1.9 In determining the capacity of the mechanical ventilation system, this Standard takes no account of the ventilating effects of uncontrolled air leakage, of natural ventilation through open windows, or of other such openings operated by the occupants.

1.10 This Standard accounts for the effect of the air-tightness of the building envelope on the difference between indoor and outdoor air pressure resulting from operation of the ventilation system and other mechanical exhaust devices.

1.11 The ventilation air requirements of this Standard are not intended to provide for the combustion and dilution air needs of vented combustion appliances. These are specified in the Standards referred to in Clause 4.2. This Standard does incorporate provisions intended to limit the depressurization of the house induced by the operation of the ventilation system and exhaust appliances in order to minimize adverse effects on the venting of vented combustion appliances, including fireplaces. It also incorporates provisions to limit house pressurization so as not to adversely affect combustion control in some vented combustion appliances.

1.12 This Standard does not consider the air supply required for combustion in fireplaces, or the supply of makeup air required to account for that exhausted through the fireplace flue. Any such requirements are above and beyond those included in this Standard.

1.13 The ventilation air requirements of this Standard are not intended to provide sufficient ventilation for indoor thermal comfort in hot weather