To improve the utilization rate of energy, the consumption of fossil energy must be reduced. In this study, a low-temperature radiant floor made of concrete is taken as the research object, and a two-dimensional low-temperature hot water radiant heating system with different concrete filling layers is numerically simulated using a computational fluid dynamics (CFD) software and finite element method. In this numerical model, a concrete sensible heat storage (SHTES) is adopted, while various types of concrete materials have been used to preliminarily analyze the influence of different concrete types on floor heat storage. The simulation results were further analyzed to determine the total heat storage during the heating period and the total heat storage and heat storage rate during the stable operation stage. The results demonstrate that the thermal conductivity coefficient of concrete floors had the most significant influence on the heat storage effect, with slag concrete demonstrating the most prominent heat storage effect. The total heat storage capacity of slag concrete after 7 h was 848.512 J. Overall, this study proposes a method to enhance the heat storage capacity of low-temperature radiant floors, while providing a design method for future solar energy storages and floor heat storages.