Local exhaust in mid-rise buildings | U.S. Green Building Council
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LEED BD+C: Multifamily Midrise | v3 - LEED 2008

Local exhaust in mid-rise buildings

MEQc5 | Possible 2 points


Reduce moisture and exposure in indoor pollutants in kitchens and bathrooms.


Prerequisites (Mandatory Measures)

5.1 Basic local exhaust. Meet all of the following requirements:

  1. For each individual dwelling unit, design and install local exhaust systems in all bathrooms (including halfbaths) and the kitchen to meet the requirements of Section 5 of ASHRAE Standard 62.2-2007. Sample requirements that relate to minimum intermittent local exhaust flow rates are shown in Table 19, below.
  2. For each individual dwelling unit, design and install the fans and ducts to meet the requirements of Section 7 of ASHRAE Standard 62.2-2007.
  3. Exhaust air to the outdoors (i.e., exhaust to attics or interstitial spaces is not permitted).
  4. Use ENERGY STAR labeled bathroom exhaust fans (except for exhaust fans serving multiple bathrooms).
  5. For all spaces outside dwelling units, meet the requirements for local exhaust from ASHRAE Standard 62.1-2007.

Credits (Optional Measures)

5.2 Enhanced local exhaust (1 point). Use one of the following strategies in every bathroom to control the use of the local exhaust fan:

  1. An occupancy sensor.
  2. An automatic humidistat controller.
  3. An automatic timer to operate the fan for 20 minutes or more after occupant leaves the room.
  4. A continuously operating exhaust fan.

5.3 Third-party performance testing (1 point). Perform a third-party test of each exhaust air flow rate for compliance with the relevant requirements: Section 5 of ASHRAE 62.2-2007 for in-unit exhaust; Table 6-4 in ASHRAE Standard 62.1-2007 for spaces outside the dwelling units.

Table 19: ASHRAE 62.2 Requirements: Minimum Air Flow Requirements for in-Unit Local Exhaust
Location Minimum Air Flow: Intermittent Minimum Air Flow: Continuous
Kitchen 100 cfm 5 ACH
Bathroom 50 cfm 20 cfm

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