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 disadvantages 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 comparative experiments. Results indicated that the inner/outer surface temperature with spectrally selective windows is higher than that with common windows, and the inner surface temperature difference of two cases can reach 1.3 °C, 4.7 °C, 10.1 °C and 6.8 °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 concentrations of 100 ppm or 200 ppm are recommended for operation during winter time.