Investigation of the influence of different room geometries and wall thermal transmittances on the heat transfer in rooms with floor heating

Heat transfer analysis is crucial for precise energy performance estimates in buildings with floor heating systems. However, existing models for predicting heat transfer at wall surfaces often lack accuracy, overlooking realistic room conditions such as corners, edges, thermal bridges, and inhomogeneous wall temperatures, thus compromising energy performance prediction. This research develops more comprehensive correlation models for heat transfer coefficients that incorporate a broader range of realistic room configurations, including room volume, floor aspect ratio, and thermal transmittance of exterior walls - factors rarely explored collectively. This study conducts computational fluid dynamics simulations to analyse the radiative and convective heat transfer and applies thermal boundary layer theory to enhance the understanding of the convective heat transfer at room edges. Results indicate that the convective heat transfer is heavily influenced by changes in thermal boundary layer structures at room edges and depends greatly on the hydraulic diameter assumed for the walls. For the radiative heat transfer, the floor aspect ratio proved crucial. The newly developed models reveal deviations up to 96.5 % from existing ones, highlighting the limited applicability of the existing models. The developed models can enhance the accuracy in predicting the energy performance of buildings with floor heating systems.