January 14, 2004—A checklist that can be used to evaluate optimal office temperature is featured in an article in the January issue of ASHRAE Journal, published by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE).
“Start the review by evaluating an occupant’s complaint to understand and validate the problem,” author Glenn Friedman, P.E., principal, Taylor Engineering, Alameda, Calif., said. “Then review the HVAC equipment performance for proper operation followed by a system design analysis.” Friedman notes that in a recent survey conducted by the International Facility Management Association, temperatures that are too cold and too hot ranked as No. 1 and No. 2 on a list of top 10 office complaints.
“It is worth validating the complaint to evaluate whether it is an HVAC issue or a management issue,” he said. “The 2001 ASHRAE Handbook, Fundamentals, points out that for typical comfort conditions, 5 percent of occupants will be dissatisfied. Research reported in ASHRAE Transactions finds that complaints occur even with perfect temperature control. If individual occupant control is not justified, do not expect every occupant to be satisfied with the same conditions.”
Problems related to temperature complaints can be caused by a variety of factors, according to Friedman. These include too little or too much capacity, too little control, lack of zoning, varying space usage, varying solar load, changes in occupancy, changes to the space envelope, drafts and diffuser performance or too little ventilation.,p> The steps to investigating a hot/cold complaint are:
- Define and validate the complaint.
- Check the HVAC system equipment operation.
- Calculate the building space loads and verify that there is sufficient capacity.
- Review zoning conflicts.
- Test the zone for good and stable temperature control.
- Review draft problems.
Measure the humidity level to verify it is below the ASHRAE Standard 55, Thermal Environmental Conditions for Human Occupancy, upper dew point limit of 62.2F.
Sometimes more rigorous and costly measures are necessary, including:
Compare the load variation characteristics of the different spaces in each zone.
Analyze the air diffusion performance index or measure the omni-directional drafts.
The article, Too Hot, Too Cold: Diagnosing Occupant Complaints, can be purchased via the online bookstore The cost is $8. The article is available free to ASHRAE members.
