A pilot study of thermal comfort in subtropical mixed-mode higher education office buildings with different change-over control strategies

Abstract

Change-over mixed-mode buildings prevent the concurrent use of air-conditioners and operable windows, thus are energy-efficient. Based on automation levels for mixed-mode control, change-over mixed-mode buildings can be classified into three types: automated, semi-manual, and manual. The objective of this research was to conduct a pilot study on the effects of different change-over mixed-mode control strategies on building occupants' thermal perception and comfort, as well as develop adaptive comfort models for mixed-mode buildings with different change-over control strategies in subtropical climates. Occupants from three types of mixed-mode control buildings were surveyed about their real-time thermal perception, while indoor environmental conditions were recorded simultaneously for a period from summer to winter. Although an overlooked factor in previous studies, this pilot study suggests that change-over control strategy may significantly affect thermal perceptions in mixed-mode buildings. Occupants who had limited control over thermal environments showed less sensitivity to outdoor conditions regardless of operation modes. In buildings where, users had a full control, a clear distinction in thermal sensation was observed when the system switched between air conditioning and natural ventilation modes. The adaptive thermal comfort model seems to be more suitable and applicable for semi-manually and manually controlled mixed-mode buildings rather than for automatically controlled mixed-mode buildings.