A comprehensive investigation of thermal characteristics of beam-blocks, concrete slab, U-boot slab and waffle slab flooring systems of buildings through CFD simulations

In this study, the effect of different types and structures of ceilings in buildings was investigated through computational fluid dynamics simulation. The studied ceilings included concrete and various types of clay, concrete blocks, simple and perforated polystyrene ceilings, prefabricated ceilings, waffle slabs, and U-boot slabs, which were studied and analyzed for spans of 6 and 8 m. For simulating fluid flow and heat transfer, the Computational Fluid Dynamics method based on the Control Volume approach was utilized. Heat transfer within air cavities occurs through free convection and radiation, while heat transfer in the solid parts of the walls is conducted through conduction. Thermal modeling of the ceilings was investigated separately for winter (heat flow upwards) and summer (heat flow downwards). Three-dimensional natural heat transfer was considered a steady laminar flow with incompressible density in the cavities. To assess the thermal performance of different ceilings, equivalent conduction coefficient, decrement factor, and time lag were studied. Ultimately, the best type of ceiling in terms of heat transfer and thermal-mass efficiency was introduced. The results revealed that the best thermal performance was achieved by concrete roofs with polystyrene blocks, while waffle-slabs roofs had the worst thermal performance.