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| v3 - LEED 2008

Outdoor air ventilation

EQc4 | Possible 3 points

Intent

Reduce occupant exposure to indoor pollutants by ventilating with outdoor air.

Requirements

Prerequisites

4.1 Basic outdoor air ventilation. Design and install a whole building ventilation system that complies with ASHRAE Standard 62.2-2007. A summary of alternatives is provided below, but the HVAC contractor should review and follow the requirements of ASHRAE Standard 62.2-2007, Sections 4 and 7.

  1. Mild climate exemption. A home built in a climate with fewer than 4,500 infiltration degree-days3 is exempt from this prerequisite.
  2. Continuous ventilation. Meet the ventilation requirements in Table 1 below.
  3. Intermittent ventilation. Use Equation 4.2 of ASHRAE Standard 62.2-2007 to demonstrate adequate ventilation air flow.
  4. Passive ventilation. Have a passive ventilation system approved and verified by a licensed HVAC engineer as providing ventilation equivalent to that achieved by continuous ventilation systems as described in Table 1.

Credits

4.2 Enhanced outdoor air ventilation (2 points). Meet one of the following:

a. In mild climates (fewer than 4,500 infiltration degree-days), install a whole-building active ventilation system that complies with ASHRAE Standard 62.2-2007.

OR

b. Install a system that provides heat transfer between the incoming outdoor air stream and the exhaust air stream, such as a heat-recovery ventilator (HRV) or energy-recovery ventilator (ERV). The heat recovery system must be listed by a certified testing lab (e.g., UL, ETL).

4.3 Third-party performance testing (1 point). Have a third-party test the flow rate of air brought into the home, and verify that the requirements of ASHRAE Standard 62.2-2007 are met. In exhaust-only ventilation systems, install exhaust ducts according to Table 7.1 of ASHRAE Standard 62.2-2007, and either test the flow rate out of the home or conduct air flow tests to ensure back-pressure of ≤ 0.20 inches w.c.

Table 1 Minimum Air Flow Requirements for Continuous Ventilation Systems, in cfm

Conditioned floor area (ft2) Bedrooms
0, 1 2, 3 4, 5 6, 7 > 7
≤ 1,500 30 45 60 75 90
1,501–3,000 45 60 75 90 105
3,001–4,500 60 75 90 105 120
4,501–6,000 75 90 105 120 135
6,001–7,500 90 105 120 135 150
> 7,500 105 120 135 150 165

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