Operation strategy and energy-saving of the solar lighting/heating system through spectral splitting

• The energy-saving benefit of a solar thermal utilization system was proved. • The feasibility of nanofluid photothermal separation was verified in building. • Energy consumption of lighting decreased by nearly 80% in office buildings. The performance of a solar lighting and heating system (SLHS) based on the spectral splitting effect of nanofluids is presented in this paper. SLHS through nanofluids would split the sunlight spectrum into different wavelength, and then introduce the visible light into the offices for lighting and absorb infrared energy to generate hot water. The Energy Plus software was used to analyze the energy consumption of typical office building located in the city of Harbin in China coupled with SLHS. Based on the simulation results two lighting zones were identified in the offices and the optimal lighting control strategy was developed for a full year. The performance models of SLHS with different light-receiving areas of 10 m 2 and 40 m 2 were simulated and validated using the existing experimental data. The overall energy-saving of the offices over a full year were analyzed using the validated model. Results demonstrated that for SLHS with the area of 40 m 2 , the rate of the energy saving in the offices due to lighting and hot water systems were 58.9%, and 19.3%, respectively. The system also had the additional benefit of reducing the cooling load of the air conditioning system during summer period together with improving the quality of the indoor environment resulting in better health and productivity of the occupants.