ASHRAE Urges Standard 62.1 Inclusion in International Mechanical Code
Use of ASHRAE’s new ventilation rate procedure in the International Mechanical Code (IMC) would reduce first costs and energy costs, argue ASHRAE officials, who have proposed that the ventilation rate calculation procedures from ANSI/ASHRAE Standard 62.1-2004, Ventilation for Acceptable Indoor Air Quality, be adopted into the IMC, which is published by the International Code Council. The code establishes minimum regulations for mechanical systems using prescriptive and performance-related provisions.
The current ventilation criteria in the IMC are based on ASHRAE Standard 62-1989. But research and information on indoor air quality and ventilation have evolved rapidly. In response, ASHRAE has enhanced its standard to include the new rate procedure. This code change would make the IMC consistent with the standard and the 2006 Uniform Mechanical Code.
The procedure requires designers to account for pollutant sources other than occupants and to account for the efficiency of ventilation systems to deliver outdoor air to the breathing zone, according to Steve Taylor, an ASHRAE member who oversaw development of the proposal.
“Ventilation systems designed using the new procedure will result in somewhat lower outdoor rates for most occupancies compared to the current code, reducing first costs and energy costs,” he said.
The proposed changes are scheduled to be evaluated in September 2006 for possible inclusion in the 2007 IMC Supplement.
In related news, ASHRAE has proposed that portions of ANSI/ASHRAE Standard 90.2-2004, Energy-Efficient Design of Low-Rise Residential Buildings, be adopted in the International Energy Conservation Code published by the ICC.
The proposal addresses two key areas where Standard 90.2 provides greater energy efficiency than the current IECC provisions, according to Chris Mathis, vice chair of ASHRAE’s Code Development Committee who oversaw the proposals. These two areas are: fenestration solar heat gain coefficients (SHGC) in southern climates and the use of modeling assumptions to quantify the benefits of exterior shading; both are applied to code compliance using the performance path.