The International Code Council approved recently an ASHRAE proposal to incorporate the prescriptive ventilation rate procedure from ANSI/ASHRAE Standard 62.1-2004, Ventilation for Acceptable Indoor Air Quality, in the IMC. The code establishes minimum regulations adopted and implemented by federal, state and local government agencies for mechanical systems in new buildings and will be included in the 2007 IMC supplement, reveals the organization’s press release.

The current ventilation criteria in the IMC are based on ASHRAE Standard 62-1989. After 20 years of IAQ research and experience with ventilation system design, ASHRAE introduced an improved version of the standard in 2004 to include the new rates and calculation procedures, and has recently published a new edition that includes requirements for the separation of areas with environmental tobacco smoke (ETS) from areas without ETS in the same building, as well as clarification of how designers must analyze mechanical cooling systems to help limit space relative humidity.

“With adoption of the new calculation procedures, we can expect to see improved indoor air quality in many previously under-ventilated multiple-zone systems”, said Dennis Stanke, chair of the 62.1 committee. “Ventilation systems with lower outdoor rates compared to the current code reduce both first costs and energy costs, while system designs that account properly for air distribution within buildings result in better indoor air quality than designs based on over-simplified air distribution assumptions.”