LEED APs for a Green Canada

EQ Prerequisite # 1: Minimum IAQ Performance

Posted by adamding76 in December 16, 2009

Prerequisite # 1: Minimum IAQ Performance

 Intent

Establish minimum indoor air quality (IAQ) performance to enhance indoor air quality in buildings, thus contributing to the comfort and well-being of the occupants

 Requirements

Meet the minimum requirements of ASHRAE 62-2001, Ventilation for Acceptable Indoor Air Quality. Mechanical ventilation systems shall be designed using the Ventilation Rate Procedure.

 Submittals: LEED Letter Template

 Submittals for audits:

  • For designs using Ventilation Rate Procedure: include a table of outdoor air flows, including assumptions such as occupancy type, floor area or estimated maximum occupancy, supply air flow rate and ventilation effectiveness, and HVAC system type to each regularly occupied space
  • For designs using natural ventilation: include a table of the free, unobstructed openable area of wall and roof openings, the floor area, the percentage ratio of openings to floor area, the distance of the space to the nearest openings for each regularly occupied space. An alternative is engineering calculations or a summary of output from a suitable computer model that shows outdoor air flows for each regularly occupied space under peak heating and cooling conditions.

 Referenced Standard: ASHRAE 62-2001, Ventilation for Acceptable IAQ

 Interpretation:

  • Use of natural ventilation is allowable instead of mechanical systems
    • Designs relying on natural ventilation are required to have wall or roof openings with unobstructed opening areas that total at least 4% of the net occupied floor area for spaces within 7.5m (25 ft) of the exterior wall. Interior spaces without direct exposure to the outdoors are required to have openings to perimeter spaces that are at least 8% of the net occupied area, or 2.3m2 (25 sq.ft) at a minimum.
  • If a mechanical ventilation system is installed, it must be designed using the standard’s Ventilation Rate Procedure.

 Strategies

 

  • Avoid choosing a site with potential IAQ problem, which include heavy traffic areas, nearby polluting industrial sites, or neighboring waste management sites
  • Identify site activities that may have a negative impact on air quality such as construction, materials installed, and chemical handling during occupancy.
  • Establish air quality standards early in the design process, and clearly state these design criteria in plans and specifications.
  • Specify, design, and install fresh air intakes away from possible sources of contamination (at least 7.5m and preferable 12m), which include loading areas, building exhaust fans, cooling towers, street traffic, idling cars, standing water, parking garages, sanitary vents, dumpsters, and outside smoking areas
  • Ensure that the outside air capacity for the ventilation system can meet the requirements in all modes of operation (consider the max occupancy load)
  • Upon project completion, include operational testing in the building commissioning report. Implement an operations and maintenance plan

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