Integrated evaluation of personal environmental control systems in a nearly net zero energy office

• Year-round logs of 274 Personal Environmental Control Systems in a nearly net-zero office. • Two daily use peaks: after arrival and after lunch. • Many activations occurred within the ASHRAE Standard 55 comfort zone. • A desk-integrated hybrid system provided localized heating for winter comfort. • Winter trial indicated comfort at mean 20.4°C operative temperature. A year-round deployment of 274 personal environmental control systems (PECS) was evaluated in a nearly net-zero energy office with an activity-based working (ABW) layout. The monitoring data revealed clear seasonal and diurnal usage patterns and showed that many activations occurred within the ASHRAE Standard 55 comfort zone, indicating that PECS were frequently used for fine-tuning rather than for discomfort relief alone. Thermal-manikin tests demonstrated distinct cooling contributions from each PECS type under 26°C conditions. Based on the observed lack of winter usage, a desk-integrated hybrid system combining foot-level warm air and a rear radiant panel was developed. This hybrid system increased local equivalent temperature (Teq) by up to 6°C and whole-body Teq by approximately 2°C under ∼20°C ambient conditions, and a winter field study (mean operative temperature 20.4°C) indicated improved comfort and perceived productivity. These findings highlight the practical potential of PECS to maintain comfort at lower heating setpoints in real ABW-based office operations, offering a viable pathway toward ZEB-aligned thermal management.