The influence of colliding supply jets on predicted and perceived thermal comfort

Abstract

The aim of this study was to examine the effect of draught caused by colliding supply jets from above the occupant on thermal comfort in laboratory conditions. The study had a repeated measures design with two conditions: A) temperature T=23.2 °C, air speed v<0.1 m/s, draught rate DR < 10 %, supply airflow Q= 30 l/s, and B) T=22.8 °C, v<0.4 m/s, DR < 30 %, Q= 70 l/s. Thirty-six volunteer university students participated in the experiment. Participants’ clothing insulation was estimated to correspond 0.71 clo and the main task was typing (activity level 1.1 met). The session lasted altogether 2.5 hours including a preparation phase and both test condition phases. Overall thermal comfort, local thermal comfort, and sensation of draught were assessed with questionnaires. The difference between conditions was mainly seen in subjective measures, but small difference was also observed in the work performance. The study highlights the importance of airflow patterns in the occupied zone of an office. The results can be used in the planning and product development of air conditioning and supply air distribution in offices.