ICC Adopts 62.1 Ventilation Rate Procedure for New Buildings
Approval of ASHRAE’s Standard 62.1 ventilation rate calculation procedure for the International Mechanical Code (IMC) marks a milestone for the high-profile mandatory-language standard after years of development aimed at code adoption.
Last week, the International Code Council approved 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.
"With adoption of the new ventilation rates into building codes, we can expect to see reduced air intake flow in many previously over-ventilated buildings," said Dennis Stanke, chair of the 62.1 committee. "With adoption of the new calculation procedures, we can expect to see improved indoor air quality in many previously under-ventilated multiple-zone systems. 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."
The current ventilation criteria in the IMC are based on ASHRAE Standard 62-1989. Based on 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. This code change makes both the IMC and the 2006 Uniform Mechanical Code consistent with the ASHRAE standard.
"The new ventilation rate procedure requires designers to account for pollutant sources from both the building and its occupants, and to account for the efficiency of different ventilation systems when delivering outdoor air to the breathing zone," Stanke said. The new requirements will be included in the 2007 IMC Supplement.