Ventilation Standards in Public Review Stage

The American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE) doesn’t write building codes, but some of the group’s standards carry as much weight as codes. That is the case with ASHRAE Standard 62 on ventilation for acceptable indoor air quality. This standard is recognized in legal circles as the “standard-of-care” to which building designers are held accountable when indoor air quality goes awry. A draft of Standard 62’s next version, now available for public comment, modifies the current Standard in many important ways. Some of these changes could add up to significantly better air quality in buildings.

The current version of this Standard, 62-1989, established the practice of providing 15 cubic feet per minute per person (cfm/p, 7 l/s/p) in the most common building types. The new draft, Standard 62-1989R, provides several different routes for calculating the recommended amount of outdoor air, resulting in ventilation rates that are slightly higher in some cases and lower in many others. The basic calculation that most designers are likely to use separates out ventilation required for the building, regardless of the number of occupants, from ventilation required to compensate for occupants. In most cases, the net result is somewhat more ventilation for lightly occupied spaces than the current standard requires, and somewhat less for crowded spaces.

More significant in their likely effect are the measures intended to get the actual air flow to the spaces to approximate the design rates. Recognizing that many systems do not operate as designed, the new standard has thirty pages devoted to documentation, construction, and commissioning to help ensure that the system will be installed and maintained properly. Also significant is that the new Standard is written in code language (using “shall” instead of “should”), to make it easier for code bodies to adopt. Over the vehement opposition of the tobacco industry, the Standard assumes that no smoking will take place in buildings and only addresses ventilation requirements to handle smoking in an appendix to the document.