From thermal sensation to thermal affect: A multi-dimensional semantic space to assess outdoor thermal comfort

Abstract

The psychometric tool known as the thermal sensation scale has been extensively used in outdoor thermal comfort research. However, this one-dimensional descriptive scale was originally developed for indoor assessments and therefore has certain shortcomings in outdoor settings. The scale contains no affective information such as pleasure and it overlooks the dynamic wind and solar radiation fluxes outdoors. Accordingly, this study develops a six-dimensional semantic framework for outdoor thermal comfort assessments comprising four descriptive - ‘thermal sensation’, ‘humidity’, ‘wind’ and ‘solar radiation,’ plus two affective - ‘thermal pleasure’ and ‘thermal intensity’ dimensions. In Phase 1 an online questionnaire recruited 135 native English-speakers to place 76 climatic adjectives into this six-dimensional semantic space. Phase 2 launched a field study with another 22 subjects locating real-time outdoor thermal experiences in the same semantic space. They were then asked to select from a subset of the 76 climatic adjectives those that best described their right here-right-now thermal experience. Validation was then performed by comparing coordinates of the 31 most frequently chosen adjectives in Phase 2 with those assigned to them in Phase 1. Good correlations (R2 > 0.65) of adjectives' coordinates between the two research phases indicate consistency regarding which adjectives best describe specific scenarios, regardless of seasons, locations, or current exposures. The results emphasise that the thermal sensation scale inadequately characterises outdoor thermal comfort experiences. This study initiates the transition of biometeorological comfort research from crude unidimensional descriptive thermal sensation scale, towards a more nuanced, multi-dimensional descriptions of subjective thermal state.