Occupant behavioral adjustments and thermal comfort with torso and/or foot warming in two cold indoor environments

Abstract

Personal warming systems have been shown to improve occupant thermal comfort in cold indoor environments. Currently, there are almost no published comprehensive studies on the examination of occupant behavioral patterns in relation to the use of personal warming systems. Thus, this study presented a human trial study to investigate the effects of torso and foot warming on thermal comfort of young female occupants in two cold indoor environments (15 °C and 17 °C), based on a water warming suit (WWS) and HYB (a WWS combined with heated socks). Besides, occupant behavior adjustments regarding water temperature setpoints for WWS and electrical heating levels for heated socks were thoroughly investigated. WWS and HYB improved occupant thermal comfort at 15 °C and 17 °C, with ≥85.7 % of ‘No Change’ OTPVs (overall thermal preference votes) observed during the last 20 min of exposure. Foot heating can significantly reduce heating demand on the upper torso, both in terms of water setting temperatures and total heating time. HYB exhibited a 25.4 % and 43.3 % shorter total duration with water setting temperatures of ≥40 °C compared to WWS at 15 °C and 17 °C, respectively. Further, occupants have employed a trial-and-error adjustment approach to determine the heating temperature/level that offers optimal thermal comfort in the cold. Lastly, the use of two PWS combinations has the potential to reduce energy consumption for indoor heating by 62.9 %, 32.1 %, and 53.7 % in cities such as San Francisco, Phoenix, and Minneapolis (baseline heating setpoint: 21.5 °C).