Influence on Occupant Responses of Behavioral Modification of Clothing Insulation in Nonsteady Thermal Environments (RP-1269)

This paper presents climate chamber experiment results in which subjects were exposed to increasing and decreasing dynamic temperature drifts while being allowed to adjust their clothing insulation as desired. The objective of the study was to substantiate the scientific basis of the recommendations on drifting temperatures as stated in ASHRAE Standard 55-2004, Thermal Environmental Conditions for Human Occupancy (ASHRAE 2004) and to extend the scope of the recommendations to cover not only thermal comfort, but also the perception of air quality, health, and performance.

The experiments addressed both the summer and winter comfort ranges of temperature, and subjects were exposed to rates of temperature change of -1.2 K/h (-2.2 degrees F/h), 0 K/h (0 degrees F/h), 1.2 K/h (2.2 degrees F/h), and 2.4 K/h (4.3 degrees F/h). Exposure duration was 4 h, except for the 2.4 K/h (4.3 degrees F/h) condition when it was 2 h.

Thermal sensation responses observed with adjustable clothing insulation did not differ from those observed with fixed clothing insulation, which were reported in an earlier paper. However, with fired clothing insulation, longer exposures (>4 h) seemed to aggravate general sick-building syndrome (SBS) symptoms, an effect that was not observed with adjustable clothing insulation.

In addition, the study did not detect any systematic influence on the performance of operative temperature ramps, regardless of the clothing adjustment opportunity. Although the current study focused on thermal comfort and SBS symptoms and performance, the recommendations on drifting temperatures, as stated in ASHRAE Standard 55 (ASHRAE 2004), were generally verified.

But, longer exposures to increasing temperatures may increase the intensity of general SBS symptoms when no opportunity to adjust clothing insulation is available.