Healthy Indoor Air Quality with Mechanical Ventilation
While it is important to seal up buildings to prevent drafts, water damage, heat loss and high energy bills, ventilation is key to maintaining the health and safety of a building. Most of our exposure to environmental pollutants occurs from breathing indoor air, which contains up to 100 times more pollutants than outdoor air. Mechanical ventilation replaces stale air from inside a home with fresh air from outside.
Ventilation can limit exposure to unhealthy indoor pollutants by removing:
- Cooking Odors
- Chemicals & VOC’s
- Carbon Dioxide Fumes from Gas Combustion Appliances
New ventilation requirements designed to improve the quality of indoor air became effective on July 1, 2014, under the 2013 Update to the California Building Energy Efficiency Standards, Title 24, Part 6 (2013 Standards). Any newly constructed single-family home, low-rise residential building, and all residential buildings with additions over 1,000 square feet must now meet ASHRAE 62.2-2010 mechanical ventilation standards. In addition, as of the 2013 Standards, the whole-building ventilation airflow required by ASHRAE 62.2-2010 must be confirmed through field verification and diagnostic testing by a HERS rater (2013 Standards, Section 150.0 (o)).
Meeting the Standards:
The 2013 Standards require local exhaust ventilation for kitchens and bathrooms and specify airflow requirements for whole-building ventilation. In order to meet the requirements, each residential building must determine its minimum ventilation rate and install the requisite fans. The required minimum ventilation rate is determined by the size of a home, the capacity of the fan which is measured in cubic feet per minute (cfm), and whether fans are run continuously or intermittently. Although permitted by ASHRAE, opening windows alone does not meet ventilation requirements of the 2013 Standards. In addition, continuous operation of central forced air system air handlers used in central fan integrated ventilation systems also does not meet ventilation requirements.
A complete description of the mandatory requirements of the 2013 Standards for Indoor Air Quality and Mechanical Ventilation including typical solutions for ventilation can be found in section 4.6 (pages 4-56 – 4-93) of the 2013 Building Energy Efficiency Standards Residential Compliance Manual.
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