Ventilation System

Ventilation System

Example whole-house and local ventilation systems.
The first step in developing a plan for upgrading ventilation systems in existing homes is to perform a thorough evaluation of existing systems and how well they are functioning. Existing systems may form the basis for meeting ventilation standards. But they may also need upgrades or replacement to meet modern requirements. This assessment should be conducted by an energy auditor or HVAC contractor. The assessment provides an approach to evaluating existing ventilation systems. It does not provide design guidance or recommendations for which new systems to install.

The U.S. Environmental Protection Agency has published a protocol for assessing indoor air quality and ventilation systems (the Healthy Indoor Environment Protocols for Home Energy Upgrades).  This protocol directs users to “determine whether the home complies with either the local exhaust requirements or the whole-house ventilation requirements of ANSI/ASHRAE Standard 62.2-2010. The EPA protocol was published in 2011. Building America recommends using the latest version of American National Standards Institute (ANSI)/American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) Standard 62.2 (2016, as of the date of publication of this guide in 2017). In 2011, a Building America team noted that ANSI/ASHRAE Standard 62.2 is, or is becoming, the most common standard referenced for ventilation requirements in homes (Evaluating Ventilation Systems for Existing Homes).

The performance of a fan—especially the delivered flow rate—is typically tested and verified using the Home Ventilating Institute (HVI) Airflow Test Procedure Publication 916. These test procedures—and the associated Product Performance Certification Procedure Publication 920—provide standardized ratings for most mechanical ventilation fan products used in homes. HVI also publishes guidelines on recommended ventilation rates in homes (How Much Ventilation Do I Need?). HVI’s recommended ventilation levels are typically higher than those recommended by ASHRAE 62.2. With kitchen ranges, for example, HVI recommends 100 CFM per linear foot of range width (e.g., 250 CFM for a standard 30-in. range). This is considerably higher than the 100 CFM minimum specified in ASHRAE 62.2.

Two documents prepared by the Consortium for Advanced Residential Buildings (CARB), led by Steven Winters Associates, formed the basis for the assessment approach described here. The reports are Evaluating Ventilation Systems for Existing Homes and Measure Guideline: Selecting Ventilation Systems for Existing Homes.