Keep an Eye on Indoor Air

July 26, 2005
Deriving the most benefit from IAQ monitoring

Environmental monitoring systems have typically been justified only for use in critical room environments, such as clean rooms, where the value of the monitoring system is offset by the high costs of product contamination. Although most facilities managers are responsible for less-critical spaces, they still face the challenge of providing healthy and productive indoor environments. Their ability to do so can have a profound financial effect on the bottom line: In the United States, estimated potential productivity gains from improvements in indoor environments range from $20 to $50 billion (1996 dollars), according to Lawrence Berkeley National Laboratory.

To-date, it has been both prohibitively expensive and impractical to monitor indoor air on a periodic or continuous basis for typical commercial buildings. The cost of populating an entire facility with high-quality, very accurate sensors is only part of the challenge. Sensors, including those which monitor very common air quality parameters (i.e. carbon dioxide [CO2]), have traditionally been a maintenance burden due to the sensor’s need for repeated calibration and its tendency to drift over time. The result is that indoor environmental quality measurements or tests are usually conducted on a reactive basis and, even then, only when the situation is extreme enough to warrant the expense. One-time environmental testing can easily cost thousands of dollars and often requires a week or more to receive results.

Recent technological advances have removed many financial and maintenance obstacles, making permanent monitoring systems a consideration for a broader range of facilities managers. Schools, healthcare facilities, and general office buildings can benefit from measuring a host of environmental conditions and use that information to respond to occupant complaints, optimize facility performance, and keep energy costs in check. In addition, feedback from the indoor environment can be used to establish baselines for building performance and document improvements to indoor air quality.

Parameters useful for evaluating indoor environmental quality and energy efficiency may be classifed into three categories:

  • Comfort and ventilation.
  • Air cleanliness.
  • Building pollutants.

Within these categories, facility-wide monitoring systems can provide independent measurement of a range of parameters, including temperature, humidity, carbon dioxide (CO2), carbon monoxide (CO), total volatile organic compounds (TVOCs), and airborne particulates. While useful for reducing investigative time and expense in responding to occupant complaints, the data and analysis from continuous monitoring can also be used proactively to optimize building performance. For example, particle counts can be used to indicate the effectiveness of the ventilation system.

Buildings are dynamic environments - and while the original basis for design may have been sound, after they are operational, the reality is that mechanical system controls drift, building use changes, and occupancy rates fluctuate. These changes can have a significant impact on the ability of the HVAC system (as designed) to maintain a balance between occupant comfort, health, productivity, and operating costs.

A facility monitoring system can be a valuable tool for improving indoor air quality, identifying energy savings opportunities, and validating facility performance. Automating the process of documenting and analyzing key parameters and providing facilities managers access to the results can better equip them to meet the challenge of maintaining healthy, productive environments.

Patricia Mormann is marketing communications manager at Newton, MA-based Aircuity Inc. (

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