Thermal pleasure in built environments: physiology of alliesthesia

Abstract

International standards that define thermal comfort in uniform environments are based on the steady-state heat balance equation that posits 'neutrality' as the optimal occupant comfort state for which environments are designed. But thermal perception is more than an outcome of a deterministic, steady-state heat balance. Thermal alliesthesia is a conceptual framework to understand the hedonics of a much larger spectrum of thermal environments than the more thoroughly researched concept of thermal neutrality. At its simplest, thermal alliesthesia states that the hedonic qualities of the thermal environment are determined as much by the general thermal state of the subject as by the environment itself. A peripheral thermal stimulus that offsets or counters a thermoregulatory load-error will be pleasantly perceived and vice versa, a stimulus that exacerbates thermoregulatory load-error will feel unpleasant. The present paper elaborates the thermophysiological hypothesis of alliesthesia with a particular focus on set-point control and the origins of thermoregulatory load-error signals, and then discusses them within the broader context of thermal pleasure. Alliesthesia provides an overarching framework within which diverse and previously disconnected findings of laboratory experiments, field studies and even comfort standards spanning the last 40 years of thermal comfort research can be more coherently understood.

The dynamics of thermal comfort expectations: The problem, challenge and impication

“…Voices can also be heard appealing to redefine our thermal comfort standards from different views like climate change [49], environmental sustainability [46], human health [50] and even cultural diversity. In a more recent contributions to the thermal comfort literature, a fundamentally different way comfort framework called 'alliesthesia' was proposed with a view to establishing greater flexibility [51,52]. At a practical level some new comfort strategies such as personally controllable comfort systems [53], moving air for comfort [54], mixed-mode buildings [55,56] and even dynamic environment control strategies [57] are beginning to receive greater attention.…”

Research on electroencephalogram to measure thermal pleasure in thermal alliesthesia in temperature step-change environment

“…One challenge for building scientists has been measuring occupants' experiences when indoor thermal environments are transient. Researchers employ the concept of alliesthesia to explain stronger perception of thermal comfort in transient environment following a physiological approach . Alliesthesia, which is a compound word with aesthesia meaning “sensation” and allios meaning “changed,” explains that the same stimuli may cause either pleasantness or unpleasantness depending on perception .…”

Thermal comfort, perceived air quality, and cognitive performance when personally controlled air movement is used by tropically acclimatized persons

“…Personally controlled air movement can promote thermal comfort in warm environments and strongly reduce energy use . In a warm environment, air movement is perceived as pleasant, a feature that is aligned with the physiological principle of alliesthesia . Based on field studies in tropical climates, human thermal comfort can be maintained by natural winds and fan‐generated airflow in naturally ventilated buildings .…”