Experimental evaluation of the micro-environmental control system in maintaining thermal comfort

The micro-environment in this study refers to the air space and environment around a person that directly impacts his/her thermal sensation. Most existing HVAC systems condition the air of the entire room including the unoccupied space, which leaves a big potential to save energy. This study aims at evaluating the performance of three existing air terminal devices (ATDs) and two heating delivering devices (HDDs) to manage the thermal balance so as not to sacrifice thermal comfort when the ambient unoccupied space temperature is expanded from 21.1-23.9 °C to 18.9-26.1 °C to reduce HVAC load. A 20-segment thermal mannequin was put in a full-scale stainless-steel chamber to test with selected ATDs and HDDs. Results show that all the three ATDs with only 50 W cooling power and the heating mat with a reflective box using 60 W heating power were able to recover the thermal comfort in a room of expanded temperature set-point. The cooling performance of the jet was increased more by increasing the supply airflow rate than reducing the supply air temperature, and 8.0 L/s flow rate could remove more than 15.6 W from the mannequin. A heating mat that heated the feet by conduction was more efficient than the heating bulb, and with 60 W heating power, it could reduce the heat loss from the mannequin by more than 12.2 W.