Comparison of the environmental, energy, and thermal comfort performance of air and radiant cooling systems in a zero-energy office building in Singapore

In an experimental study set in Singapore's tropical climate, we evaluated the thermal environmental performance, energy consumption, and thermal comfort of air and radiant cooling systems, operating at an operative and air temperature of 26 °C. 78 participants across five groups answered thermal comfort surveys in a crossover study design. Environmental performance metrics indicated that both systems produced similar conditions, with a noticeable difference in air velocity. The mean radiant temperature to air temperature difference was less than 0.5 °C in both systems. The radiant system exhibited a 33 % higher heat flux extraction than the air system and required less electrical power for the transportation of the cooling medium and ventilation air. Overall, the radiant system used 4 % less energy than the air system when controlled at 26 °C and 34 % when operated at 23 °C. Results show that radiant and air systems provided equal thermal comfort in cooling, with over 60 % of participants expressing satisfaction and ∼ 20 % voted neutral thermal satisfaction. ∼ 40 % of participants preferred cooler conditions, and ∼ 30 % desired increased air movement.