Preferred vs neutral temperatures and their implications on thermal comfort and energy use: Workplaces in Japan, Norway and the UK

This study recommends the application of “preferred temperature” rather than neutral temperature in thermal comfort studies, particularly when focused on finding the range of comfort temperatures. Currently, neutral temperature is considered as comfort temperature of the occupants in thermal comfort research. This study challenged this view and questioned the use of neutral temperature in thermal comfort studies, standard comfort zone and thermal comfort standards. Field test studies of thermal comfort were carried out on about 5,000 respondents in three distinct workplace contexts: Japan, Norway and the UK. Thermal sensation, preference and environmental measurements were collected and analysed using the Griffiths method. Preferred and neutral temperatures were compared in these three contexts and differences were observed. Overall, this study suggests that thermal preference (TP) is more likely to be a more accurate measure in assessing thermal comfort and particularly the direct implication of it in the real world context (e.g. changing the room temperature) is more likely to result in occupant comfort. It suggests that a neutral thermal sensation does not guarantee thermal comfort of the occupant, as the occupant may want other sensations than neutral (e.g. the occupant still prefers a change although feeling neutral). It is essential to recognise that non-neutral thermal sensations are considered as thermal comfort for some occupants and to include this in future research as well as the direct implication in setting the room temperature and the energy performance of the building.