Combined effects of visual-acoustic-thermal comfort in campus open spaces: A pilot study in China's cold region

To investigate the combined effects of thermal, acoustic and visual comfort in open spaces, this study selected five typical spaces on a university campus with five common sounds (broadcasting music, running water & birdsong, wind (a gentle breeze) & insects, crowds, and machines) in a cold region of China. 418 volunteers were asked to complete a subjective sensory questionnaire in a randomly combined audio-visual environment while meteorological measures were taken on-site. Four primary outcomes emerged. First, broadcasting music improved individual subjective thermal comfort votes (TCV). Under the moderate heat stress (0.5 = thermal sensation vote [TSV] < 2.5), a comfortable acoustic environment helped reduce individuals' subjective TSV and increase TCV. Second, the subjective acoustic comfort vote (ACV) of broadcasting music, wind & insect sound and machine noise decreased with the increase of Universal Thermal Climate Index (UTCI); respondents perceived crowds, machines and wind & insects louder when TCV = 2 and -2. Third, under no thermal stress (-0.5 <= TSV < 0.5)/moderate heat stress (0.5 <= TSV < 2.5), TSV increased with increasing illumination intensity (LUX). Under the strong heat stress (2.5 <= TSV <= 3), there was no significant difference in TCV among subjective visual comfort vote (VCV) levels. Finally, when the LUX class was neutral/slightly bright, respondents felt darker in thermo-neutrality. Additionally, VCV and TCV were positively correlated under each LUX class.