Thermal comfort benefits using a convective–radiative Personalized Environmental Control System for intermittent heating

In intermittent heating scenarios, conventional terminals such as fan coil units and underfloor heating often struggle to simultaneously deliver rapid thermal response and satisfactory occupant comfort. Personalized Comfort Systems (PCS) have emerged as a promising solution to address differentiated thermal demands and improve individual comfort in indoor environments. In this study, a convective-radiative coupled Personalized Environmental Control System (C-R PECS), integrating the characteristics of rapid thermal response from convective heating and better thermal comfort from radiant heating, was proposed and prototyped to enhance occupant comfort during intermittent heating. To evaluate its performance, both thermal manikin and human subject experiments were conducted in a climate chamber under room temperatures ranging from 16 to 20 °C, with 16 participants involved in the tests. In the experiments, the C-R PECS was operated following a convection-first and subsequently radiation strategy. Results from the thermal manikin showed that the heating rate of the C-R PECS reached 0.16 K/min, which was approximately 4 times higher than that of the single radiant mode, and the maximum whole-body equivalent temperature difference (Δteq) could reach 2.5 K. The most significant effect was observed in the lower leg region, where the Δteq reached 4.4 K—thereby achieving the desirable "cool-head-warm-feet" effect. Subjective evaluations further demonstrated that under thermally non-neutral conditions (18 °C), participants using the C-R PECS achieved a corrective power (CP) of 3.2 K within 10 minutes, which was maintained until the steady state, effectively enhancing thermal sensation and overall comfort.These findings confirm that the C-R PECS, as an innovative design strategy, can significantly enhance thermal comfort in intermittent heating applications, offering both rapid response and localized thermal comfort.