ASHRAE has published an updated version of Standard 62.1, adding new requirements regarding natural ventilation, exhaust systems, and indoor air quality (IAQ) procedure to the standard. ANSI/ASHRAE 62.1-2010, “Ventilation for Acceptable Indoor Air Quality,” sets minimum ventilation rates and other requirements for commercial and institutional buildings.

Among the changes to the 2010 standard are modifications to the Natural Ventilation Rate Procedure, which now requires most buildings designed to meet the natural ventilation requirements to also include a mechanical ventilation system designed to meet the ventilation rate or IAQ procedures. The mechanical system is to be used when windows are closed due to extreme outdoor temperatures, noise, and security concerns.

Another change relocates requirements related to exhaust systems to a new section, clarifying that exhaust requirements apply to all buildings regardless of the procedure used to determine outdoor-air-intake flow rates.

The IAQ procedure, which allows for the calculation of the amount of outdoor air necessary to maintain the levels of indoor-air contaminants below recommended levels, has been made more robust by increasing requirements for using the “similar building” design approach and by clarifying other requirements.

The cost of Standard 62.1-2010, Ventilation for Acceptable Indoor Air Quality, is $69 ($59 ASHRAE members). To order, visit