A field study on thermal environment and occupant local thermal sensation in offices with cooling ceiling in Zhuhai, China

• Compared with experimental cases, people in real office were in warmer environment.
• Temperatures of ceiling and air showed linear relation when room was fully cooled.
• MRT exerted higher correlations with subjective responses than air temperature.
• Sensation of local body parts influenced both overall sensation and comfort.

This study aims to investigate thermal environment and occupant local thermal sensation in offices with cooling ceiling. A field survey combining environment measurements and questionnaires was conducted in offices in Zhuhai, China. The obtained results indicated that compared with experimental conditions, occupants in real crowded offices experienced warmer environment because the mean radiant temperature (MRT) was higher than the air temperature due to the shelter effect of indoor furniture etc. MRT also showed higher correlations with both overall thermal sensation (OTS) and overall thermal comfort (OTC) than air temperature because a great part of heat transferred through radiation. Air temperature showed linear correlation with the ceiling temperature when cooling ceiling could fully handle the cooling load, but supplementary air cooling was also necessary for radiant cooling systems in real offices. Moreover, local thermal sensation (LTS) of different body parts showed great differences due to many factors such as clothes and adaptive behaviors, and it significantly influenced both OTS and OTC. Particularly, head, hand, leg and foot had considerable effects on OTS while head and leg showed influences on OTC. In addition, this paper also validated against some important results of previous studies and provided references for future work.