Design and performance of the solar-powered floor heating system in a green building

In the green building of Shanghai Research Institute of Building Science, the evacuated tubular solar collectors with a total area of 150m2 were installed to provide heating for the covered area of 460m2. The floor heating coil pipes were made of high-quality pure copper with the dimension of Φ 12×0.7mm. Under typical weather condition of Shanghai, the average heating capacity was 25.04kW during the working hours from 9:00 to 17:00, which was sufficient to keep indoor thermal environment. The average electric COP of the floor heating system was 19.76 during the system operation. Compared with the widely used air-source heat pump heating systems with the electric COP of 3.5 in Shanghai, the solar-powered floor heating system shows great potential in energy conservation in winter. With respect to the whole heating period, the solar fraction was 56%. According to the performance analysis of the system with ambient parameters, it was observed that the system performance could be greatly enhanced with the increase of daily solar insolation. However, the system performance varied slightly with average ambient temperature. Compared with average ambient temperature, daily solar insolation had a more distinct influence on the performance of the solar-powered floor heating system.