ASHRAE. 2010. ASHRAE Standard 62.2-2010, Ventilation for Acceptable Indoor Air Quality in Low-Rise Residential Buildings. Atlanta: American Society of Heating, Refrigeration, and Air-Conditioning Engineers, Inc.
Intermittent Supply/Exhaust Fan Ratings
 |
Scope
Local Mechanical Exhaust
Intermittent supply and exhaust fans rated at ≤ 3 sones by manufacturer, unless rated flow ≥ 400 CFM
- Install fans rated by the manufacturer at 3 sones or less.
- If the fan has a rated flow equal to or above 400 CFM, the requirement described in “A” does not apply.
Notes:
Fans exempted from this requirement include HVAC air handlers and remote-mounted fans. To be considered for this exemption, a remote-mounted fan must be mounted outside the habitable spaces, bathrooms, toilets, and hallways and there shall be ≥ 4 feet of ductwork between the fan and intake grill. Per ASHRAE 62.2-2010, habitable spaces are intended for continual human occupancy; such space generally includes areas used for living, sleeping, dining, and cooking but does not generally include bathrooms, toilets, hallways, storage areas, closets, or utility rooms.
|
|
Description
Exhaust fans are often installed in bathrooms, kitchens, and laundry rooms to provide intermittent, localized ventilation. Fans that are overly noisy are more likely to be turned off quickly, perhaps too quickly to work effectively, for example to remove all the moisture in the bathroom after a shower or in the kitchen after boiling water. To improve indoor air quality and moisture control, quiet fans should be specified and installed. Fan noise is measured in sones; the lower the sone, the quieter the fan. Exhaust or supply fans installed for intermittent use should have a sone rating of 3 or less. For comparison, a quiet refrigerator operates at about 1.0 sones.
Fans exempted from this requirement include fans with a rated flow rate equal to or greater than 400 CFM, HVAC air handlers, and remote-mounted fans. To be considered exempt, a remote-mounted fan must be mounted outside the habitable spaces, including bathrooms and hallways, and there must be at least 4 feet of ductwork between the fan and intake grille.
For more on exhaust fan ratings, see Continuous Supply/Exhaust Fan Ratings and Bathroom Fan Ratings.
How to Select Low-Sone Supply and Exhaust Fans
- When specifying and purchasing exhaust or supply fans that will be used intermittently for local exhaust within the home, select quiet fans with a sone rating of 3.0 or less. The sone rating should be listed on the product label or in the manufacturer’s literature.
Figure 1 - The manufacturer’s label found on this exhaust fan housing shows a sone rating of 2.5. 
Ensuring Success
In homes where a fan is installed to provide intermittent supply or exhaust, the HERS rater should inspect to ensure that the fan’s noise level is rated at less than or equal to 3.0 sones by the manufacturer (not required on fans with flow rates equal to or greater than 400 cubic feet per minute).
Climate
No climate specific information applies.
Right and Wrong Images
Presentations
None Available
Videos
None Available
CAD Images
None Available
Compliance
ENERGY STAR Version 3, (Rev. 6)
HVAC System Quality Checklist, Ventilation & Exhaust Fan Ratings (Exemptions for HVAC and Remote-Mounted Fans). Intermittent supply and exhaust fans rated at ≤ 3 sones by manufacturer when producing no less than the minimum airflow rate required by Section 8 of the checklist, unless rated flow ≥ 400 CFM. Fans exempted from this requirement include HVAC air handlers and remote-mounted fans. To be considered for this exemption, a remote-mounted fan must be mounted outside the habitable spaces, bathrooms, toilets, and hallways and there shall be ≥ 4 feet of ductwork between the fan and intake grill. Per ASHRAE 62.2-2010, habitable spaces are intended for continual human occupancy; such space generally includes areas used for living, sleeping, dining, and cooking but does not generally include bathrooms, toilets, hallways, storage areas, closets, or utility rooms.
Exhibit 1: Mandatory Requirements. Certified under ENERGY STAR Qualified Homes Version 3.
ANSI/ASHRAE Standard 62.2.-2010
Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings. The standard applies to spaces intended for human occupancy in single-family homes and multifamily homes that are three stories or less, including manufactured and modular homes. The standard provides minimum acceptable requirements for mechanical and natural ventilation in these spaces.
This topic is not specifically addressed in the 2009 IECC.
This topic is not specifically addressed in the 2009 IRC.
This topic is not specifically addressed in the 2012 IECC.
This topic is not specifically addressed in the 2012 IRC.
Case Studies
None Available
References
-
ASHRAE Standard 62.2-2010, Ventilation for Acceptable Indoor Air Quality in Low-Rise Residential Buildings
-
DOE Challenge Home National Program Requirements
DOE. 2012. DOE Challenge Home National Program Requirements (Rev. 02). Office of Energy Efficiency and Renewable Energy, U.S. Department of Energy, Washington, D.C.
-
ENERGY STAR Qualified Homes, Version 3 (Rev. 06) Inspection Checklist for National Program Requirements
EPA. 2012. ENERGY STAR Qualified Homes, Version 3 (Rev. 06) Inspection Checklist for National Program Requirements. U.S. Environmental Protection Agency, Washington, D.C.
-
Fans, Ventilating for Consumers
EPA/DOE. 2012. Fans, Ventilating for Consumers. ENERGY STAR, U.S. Environmental Protection Agency and U.S. Department of Energy, Washington, D.C.
-
HVAC System Quality Installation Rater Checklist
EPA. 2011. HVAC System Quality Installation Rater Checklist. U.S. Environmental Protection Agency, Washington, D.C.
-
Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings (ANSI/ASHRAE 62.2-2010)
American National Standards Institute (ANSI) and American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE). 2010. Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings. ANSI/ASHRAE 62.2.-2010. American National Standards Institute, Washington D.C.
