Thermal comfort and visual interaction: a subjective survey

The application of the human factors’ principles stated the need for rethinking the indoor built environment design which should also conjugate the binomial energy saving-Indoor Environmental Quality (IEQ). This means that the optimization of a single IEQ component should also account for possible antagonistic or synergic effects. The hue-heat hypothesis is based on the idea that light and colours can affect the thermal perception. Particularly, spectral power distributions of light shifted to short wavelengths seem to promote a cooler thermal perception and the vice-versa. Several efforts have been made in the past to characterize the effect of the colour of light on thermal comfort, with experiments giving conflicting results mainly due to a bad control of lighting and microclimatic parameters and to the use of not robust measurement protocols. To verify the hue-heat hypothesis, in this study 81 subjects have been exposed to two different lighting scenarios characterized by warm and cool light at a fixed task illuminance value (300 lx) under winter thermo-hygrometric conditions in a special test room provided with white-tuning LED sources. Preliminary findings seem to confirm that warm light results in a warmer thermal sensation with a potential improvement of comfort conditions.