Proposal for a Design Method for Ceiling Radiant Cooling System Using CFD Analysis

ABSTRACT

Water‐based ceiling radiant cooling systems are increasingly adopted in Japan for thermal comfort and energy savings. However, conventional design methods relying on assumed target operative temperatures (OT) and uncooled surface temperatures often create discrepancies between expected and actual indoor environments. This complicates cooling capacity estimations and panel requirements, especially when combined with convection systems. This study proposes C‐DM, a novel design method integrating computational fluid dynamics (CFD) into the conventional ASHRAE approach. By utilizing CFD to replicate actual phenomena, C‐DM determines multiple parameters simultaneously and employs feedback control to accurately establish the radiant panels' cooling capacity needed for the target thermal environment. To evaluate its effectiveness, C‐DM was applied to redesign a real office equipped with a ceiling radiant cooling system. Results demonstrate that the radiant panels' cooling capacity can be increased by 15.26 W/m ² without compromising indoor thermal comfort, enabling highly effective system utilization. Furthermore, while maintaining the existing ratio of radiant to convection air conditioning, the required number of panels can be reduced by 0.21 units per square meter of floor area.