Human thermal comfort under lateral radiant asymmetries

• Exposure duration and body's thermal condition significantly affected thermal comfort. • Thermal sensation decreased with time, getting more uncomfortable under cool wall. • Warm wall limits of Δ t pr are 4.4 °C and 1.8 °C for 3h and 2h exposures. • Cool wall limit of radiant temperature asymmetry is 1.8 °C for 1h exposure. Occupants’ thermal comfort in buildings may be affected by the cool wall and warm wall, which is attributed to the effect of asymmetric radiation. However, the previous majority of the researches on asymmetric radiation were mainly about the comfort limits under thermally neutral condition within 1∼1.5 h but had not considered the effect of exposure duration and the condition beyond neutral. To investigate the human thermal comfort under an asymmetric environment caused by the cool wall and warm wall, forty-four subjects were exposed to neutral air temperature with lateral radiant asymmetries in winter and summer for 3 h. The results indicated that the cool wall caused thermal discomfort easier than the warm wall because the thermal sensation decreased and deviated from neutral with time. Subjects' sensitivity of local parts to asymmetric radiation was affected in the conditions beyond neutral, thus their acceptability to asymmetric radiation decreased. The currently used limits of radiant temperature asymmetry tended to underestimate the local discomfort due to the walls. For the conditions tested, The limits of 5 % dissatisfaction in radiant temperature asymmetry were 4.4 °C (180 min) and 1.8 °C (60 min and 120 min) for the warm wall, and 1.8 °C at 60 min for the cool wall. .