Cashins & Associates Blog

Indoor Air Quality - Office Comfort

Posted by Mike Cashins on Fri, Feb, 10, 2012 @ 16:02 PM

Hot and cold office“I’m too hot! I’m too cold! ” Have you heard these complaints in your office? Adverse thermal comfort and air quality issues in the office will impact employee productivity, efficiency, comfort, and morale. It will increase costs unless properly addressed. The primary causes of such issues can often be addressed and solved by understanding work and HVAC system conditions and how they contribute to such problems. Once the risk factors relating to these conditions are understood, solutions to the issues often become apparent.

Cashins & Associates experience with hundreds of investigations in office and commercial buildings has found that modifications, adjustments and maintenance of HVAC systems most often provide rapid solutions to most indoor air quality (IAQ) and allied thermal comfort issues.

Thermal Comfort: “I’m too hot!” “I’m too cold!”

A survey by the International Facilities Manager Association found thermal comfort issues, too hot and too cold, as the #1 and #2 office complaints. Due to the complexity of modern HVAC systems, simple adjustments to thermostats do not necessarily solve the complaints. If they did, thermal concerns would not be such a common issue.

We have found that well intentioned, but improper, system adjustments made to address thermal complaints often leads to system imbalances and poor air flow. Such adjustments, in turn, often lead to more widespread thermal complaints. Additional adjustments can, in the longer term, lead to air flow restrictions. Such restrictions often lead to air quality complaints.

Recognizing, evaluating and addressing the base cause of thermal complaints will often lead to a permanent solution not only to the thermal comfort issue but prevent potential ensuing office IAQ problems.

Many factors influence thermal comfort and the perception of thermal conditions. Such factors include temperature, radiation, humidity, air movement, vertical and horizontal temperature differences, temperature drift, personal activity and clothing.

Temperature, temperature drift, and humidity factors are most often fairly well controlled by simple building system adjustments. Radiation, that is, solar window loading, is normally addressed and readily controlled by window treatments such as blinds and curtains. Activity levels and clothing are occupational and personal choice factors. However, air movement and air distribution are areas that are commonly overlooked. These factors, when not properly adjusted can cause thermal discomfort.

For most individuals, comfort can be maintained when the following conditions are met in the office:

  • Air temperature between 73 – 77 F.
  • Relative humidity between 30 - 60%
  • Maximum air flow of 50 fpm (cooling) and 25 fpm (heating)
  • A 5 F. maximum temperature gradient from the floor to 6 foot level

The above assumes sedentary to slightly active individuals, appropriately and seasonably dressed.

Unwanted air flow, or drafts, can be controlled and corrected if their source is identified. Because of draft or air flow’s important influence on skin temperature, skin wetness, convective and evaporative heat loss, and thermal sensation, it has always been incorporated into thermal comfort standards. In current standards, the minimizing of draft is addressed by placing rather low limits on the allowable mean air speed as a function of air temperature. These limits are difficult to maintain.

Our Next Blog Post Will Address a Condition Known as "Cold Air Dumping".

Download Our Free Paper that Provides a Summary of Key Indoor Air Quality Issues. This is a great resource for Facility Managers, Health and Safety Professionals, Industrial Hygienists and Office Managers.

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Topics: industrial hygiene, indoor air quality, ventilation assessment

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