Light exposure effects on the perception of the thermal environment

A wider range for acceptable indoor temperatures can reduce building energy consumption and may be beneficial for health. In the current study, we investigated the influence of the intensity and spectrum of white light exposure on thermal comfort and sensation. In two well-controlled laboratory studies with 35 healthy young adult females, we tested the effect of the correlated colour temperature of light (2700K and 6500K, both 55lx) and the intensity of light (5lx and 1200lx, both 4000K) on thermal comfort and sensation. The light exposures were provided during cool, neutral and warm thermal conditions. Core and skin temperatures were measured. Thermal comfort and thermal sensation were not significantly affected by the light intensity or relative correlated colour temperature. The preferred lighting conditions differed between individuals. Interestingly a significant positive correlation was found between visual comfort and thermal comfort. This result implies that visually comfortable conditions may improve thermal comfort, but individual preferences should be taken into account. The main conclusion therefore is that thermal discomfort can partly be alleviated by lighting conditions that result in a higher perceived visual comfort. Field studies are required to demonstrate the practical relevance of the interaction between light exposure and ambient temperature.