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Facility managers can use ASHRAE 62.1's recommended ventilation rates to get an idea of whether the rates in their buildings are too high (and therefore not energy efficient) or too low (and therefore not conducive to good indoor air quality).
Now, no one will likely check whether a building is in ongoing compliance with ASHRAE 62.1 on an outside airflow basis, but if there's ever a problem, it's going to look bad if you don't know whether you're in compliance or not. It's good risk management best practice to have the data available.
Another aspect of compliance with 62.1 is preventive maintenance, which also fosters good indoor air quality. If you're measuring the percentage of prescribed preventive maintenance being completed, based on the maintenance manual that ASHRAE 62.1 requires must be provided when the building is handed over, a high percentage of completed preventive maintenance points to likely good indoor air quality. It means you're regularly checking filters, regularly examining dampers to make sure they're opening and closing properly, and making sure drain pans aren't full of water.
ASHRAE 62.1 also provides a standard (maximum of 65 percent in the 2007 edition) for relative humidity, which also plays into indoor air quality. Air that is too wet promotes mold growth. But air that is too dry (especially in the winter) can be just as bad for indoor air quality, causing occupant's mucous membranes to dry out and making them uncomfortable.
Measuring the dew point temperature and humidity, and benchmarking that data, is one of the more important, yet overlooked, parts of maintaining good indoor air quality.