Evaluation of thermal comfort in building transitional spaces - Field studies in Cardiff, UK

Transitional spaces have been widely applied in building designs. They may account for 10-40% of total volume in different types of buildings. Maintaining an acceptable level of thermal comfort for transitional spaces poses challenges to building designers and engineers. However, there is not in general a recommended acceptable comfort range for transitional spaces, nor are there specific thermal comfort prediction methods. This paper aims to investigate the thermal environmental performance and people's adaptive comfort in transitional spaces, by conducting field studies, which include on-site questionnaire surveys and physical measurements. Field studies were carried out for three selected case study buildings in Cardiff, each having some forms of transitional space. They were the National Assembly for Wales Senedd, the Hadyn Ellis Building and the Royal Welsh College of Music and Drama. The total responses from the questionnaire surveys were 736 and 580, for all buildings, during the summer period in 2017 and the winter period in 2018 respectively. This paper first presents the findings from the field studies, followed by in-depth analysis of human adaptability to thermal environment. Strong correlations were identified between clothing value and indoor operative temperature. People's adaptability to the thermal environment is confirmed, with nearly 80% of the respondents opting for self-adaptive actions to overcome uncomfortable situations. The identified 90% acceptability comfort band (-0.5 < TSV < +0.5) were 4.0 degrees C and 4.2 degrees C for the summer period and the winter period respectively, implying that a fine control of the indoor temperature to maintain an acceptable comfort level is not necessary.