An experimental evaluation of the thermal performance of lightweight radiant ceiling panel designs

• Prefabricated, modular, and lightweight hydronic panel design variants are developed and experimentally evaluated. • Small changes in design and construction methods can notably increase panel thermal capacity and reduce response time. • Combining canopy-to-canopy capillary mat with a metal heat distributing pan and adhesion method results in highly effective heat transfer. Fast reaction time is achieved through mass reduction while retaining uniform and effective thermal distribution. Dynamic indoor environments, such as those recorded at perimeter zones of office buildings, require conditioning solutions that can respond quickly to dramatic changes in solar gain to keep occupants comfortable. Lightweight radiant ceiling panels have received much attention as a potential solution to this problem. However, while many designs have been proposed, these panels have largely focused on enhancing thermal performance often through complex designs, which can compromise the practicality of the solution. In filling this void this paper explores six radiant panel design variants which are relatively simple to pre-fabricate, modular, and both accessible (low-cost) and extensible (can potentially accept several different radiant surfaces). The impact of thermal mass and thermal connection on each panel’s performance is evaluated through three experimental test runs recording heat flux, surface temperature, and reaction time. The findings indicate that a lightweight, well-insulated panel with a conductive metal pan encapsulating a canopy-to-canopy capillary tube mat, and a strong adhesive bond with the finishing surface yields a high thermal performance. One design was capable of yielding 160 W/m2 heat flux, with a 3 °C difference between the water and the radiant surface temperatures and a seven-minute response time (time constant). The results indicate that simply constructed radiant panels fabricated from readily available materials can perform as well, if not better than their more complex counterparts. This is particularly significant as the simplicity of the design opens opportunities for future design development, including the adaptation of the radiant surface materials and coatings.