Occupant Interactions and Perceptions of Personal Environmental Control Systems under Different Ambient Temperatures in Summer Conditions

This study aimed to examine the behavior of users of a personal environmental control system (PECS) when subjected to a room air temperature change. The experiments were conducted in a full-scale laboratory office environment with 12 cubicles, all equipped with PECS. Before the test day, participants were taught how to adjust the PECS. On the test day, they were given 30 minutes to settle into the cubicle and were advised to freely turn the PECS on or off or adjust its settings both before and during the test, mimicking an expected usage condition in offices. The PECS settings were recorded continuously from the preparation period until the end of the test. The tests were conducted under summer condition (23.3°C-25.6°C). Each test included two sessions. Taking the summer conditions as an example, in the first session, the ambient room temperature was maintained at 23.3°C for 40 minutes, followed by a 30-minute rest period during which the temperature increased to 25.6°C. The 2nd session, 25.6°C, lasted 40 minutes. During both sessions, participants completed cognitive tasks and questionnaires on thermal perception and device feedback. The results showed that most participants used the micro environmental control system (μX), with usage rates increasing from 78.5% in Session 1 to 88.3% in Session 2. Thermal comfort scores remained positive despite variations in thermal sensation between test days. Regarding user acceptance, 57% of participants preferred the device, while common suggestions included making it more compact, reducing noise at high fan speeds, and simplifying the control interface. This study provides insights into PECS user behavior and identifies design improvements needed for broader commercial implementation.