Thermal Pleasure and Alliesthesia in the Built Environment

Abstract

The aim of this thesis is to propose the physiological concept of alliesthesia as a suitable framework for understanding thermal environmental perception under dynamic conditions. Paper 1 outlines the theoretical basis of the alliesthesia hypothesis, and papers 2-4 lend support through the presentation of empirical evidence from a series of human-subject laboratory tests. The principal conclusion is that strong subjective discomfort is not a necessary precondition for thermal pleasure. Alliesthesia remained viable even within the physiological thermoneutral zone, although it was less pronounced and more ambiguous in those moderate scenarios. Positive hedonic tones were elicited during innocuous exposures at the margins of the thermal comfort zone by applying moderate local skin temperature changes that were contrapuntal to mean skin temperature. This phenomenon was termed ‘spatial alliesthesia.’ The hedonic tone attached to thermal environmental stimuli exhibited pronounced between-subject variability. The most useful variable for distinguishing the tone and magnitude of thermal pleasure response to localised thermal stimuli was the intensity of the subjects’ displeasure in the preconditioning environment. The magnitude of change in local skin temperature also had a significant effect on perceived pleasantness of localised thermal stimuli. These findings suggest it may be possible to develop a model of spatial alliesthesial response to stimuli. The findings emanating from this thesis could start the discussion on how it could be leveraged in the provision of thermal comfort in nonsteady-state environments. It may be possible to increase occupant satisfaction whilst simultaneously reducing energy consumption through the correct implementation of targeted thermal stimulation delivered locally by personal environmental control (PEC) systems.