Subjective Response to Overhead Thermal Radiation

Abstract

Forty subjects in two experiments experienced conditions in which ceiling temperatures varied between 26.5°C and 45°C. Air temperature, mean radiant temperature, air velocity, and humidity were held constant. Experimental variables consisted of two levels of seat height, subject baldness, and environmental temperature. The subjects appraised the environmental conditions by use of a 34-item semantic differential questionnaire. Baldness and seat height were unimportant factors, but ceiling temperature significantly affected warmth assessment. Conditions of higher ceiling temperature were perceived as cooler than those with the same mean radiant temperature and lower ceiling temperatures. Raising the air temperature did not increase sensitivity to overhead radiation, and raising the ceiling temperature did not cause discomfort. The results indicate greater sensitivity to radiant exchange with walls than with the ceiling, and that European upper limits for ceiling temperature are unduly restrictive.