Experimental study of indoor light/thermal environment with spectrally selective windows using ATO nanofluids in winter

As a weak link in energy efficient buildings, the building glass windows have been developing towards energy saving, comfort and adjustability. The dynamic windows and static windows have the disadvan-tages of instability as well as low spectral flexibility and poor seasonal adaptation respectively, to solve the above problems, this study proposes a novel semi-dynamic fluidic window filled with ATO/water nanofluids to bridge the gap between dynamic windows and static windows, and its performance has been experimentally studied. Firstly, the operating principle of the novel spectrally selective windows with overturn function is depicted during summer and winter operating periods. Meanwhile, the indoor light/thermal environment is discussed with the effect of volume concentrations ATO nanofluids, by com-parative experiments. Results indicated that the inner/outer surface temperature with spectrally selec-tive windows is higher than that with common windows, and the inner surface temperature difference of two cases can reach 1.3 degrees C, 4.7 degrees C, 10.1 degrees C and 6.8 degrees C, with volume concentration of 100 ppm, 200 ppm, 500 ppm and 1000 ppm respectively. Meanwhile, heat absorption of nanofluids delays the time of indoor peak temperature and increases the indoor air temperature during the afternoon and evening period, with a delay time of 33 min at 1000 ppm volume concentration. Additionally, it is found that with volume concentration increases, indoor illuminance significantly decreases, and the optimal concentra-tions of 100 ppm or 200 ppm are recommended for operation during winter time.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

This study proposes a novel semi-dynamic fluidic window filled with ATO/water nanofluids to bridge the gap between dynamic windows and static windows. The research experimentally studied its performance and found that the spectrally selective windows have higher surface temperatures and longer delay time for indoor peak temperature compared to common windows.