The effect of solar radiation on dynamic thermal performance of floor heating systems

This paper presents a numerical investigation of transient heat transfer in floor heating systems using a three-dimensional explicit finite difference model. The study focused on the influence of the cover layer and incident solar radiation on floor temperature distribution and on energy consumption. Complete and partial (area) carpets were considered as well as hardwood cover layers over concrete or gypcrete thermal storage. Experimental and simulation results for an outdoor testroom reveal that solar beam radiation can cause a local floor surface temperature in the illuminated area 8°C higher than that in the shaded area. Partial carpet cover further increases floor surface temperature differences up to 15°C when solar radiation is absorbed. Solar radiation stored in the floor thermal mass was found to reduce heating energy consumption significantly (30% or more). Increase of thermal mass thickness from 5 cm to 10 cm did not lead to higher energy savings with conventional proportional-integral control. Advanced control algorithms need to be developed to maximize energy savings while maintaining good thermal comfort.