Realtors often say there are three important factors in purchasing real estate: location, location, location. Similarly, for a building owner to understand an engineer's design intent for the filtration system, there are three important factors: communication, communication, communication.

These days, a growing range of sources offer information on air filters for commercial and institutional buildings. This growing attention is understandable, given the importance of IAQ in the design and operation of today's buildings and the major role that filtration plays in maintaining an acceptable indoor air environment.

Technical organizations and HVAC equipment manufacturers are devoting significant resources to IAQ in buildings where people live and work. Engineering and maintenance managers must understand not only the importance of filtration on IAQ but also how to apply available filtration technology in the most cost-effective ways for their buildings. Energy and total costs for filter replacement often are $0.70 to $1.80/person/month, according to one industry source. This statistic is valid for a wide range of filtration efficiencies, and the cost is relatively insignificant compared to the costs associated with building occupants, such as salaries, rent, and health insurance.

So it pays to know the original design intent of the filtration design and to follow that design intent as closely as possible. If significant changes occur in the use of a building, managers must re-evaluate the design intent and change or adjust it to meet the needs of the building and its occupants.