Investigation on the lighting/heating performance of tubular daylighting devices (TDDs) based on nanofluids

Abstract

Lighting is necessary for all kinds of buildings and consumes a large amount of electricity. Tubular daylighting devices (TDDs) can serve as an alternative, but they may also have thermal effects on the indoor environment, which has not been studied yet. In this paper, a lighting-heating coupled TDDs system was designed and built, to improve the use of TDDs for building energy savings and sustainability, where antimony tin oxide (ATO) nanofluids were introduced to absorb extra unexpected heat and then supply domestic hot water. Meanwhile, a new method was developed to calculate the annual amount of energy output of TDDs under different mass concentrations of ATO nanofluids. Results showed that the ATO nanofluids of 100 ppm can absorb ∼ 50% solar radiation coming along with more efficient visible lighting. Furthermore, in the case study in Beijing, TDDs with 100 ppm ATO nanofluids could generate over 10 tons of domestic hot water while saving 30.9 kWh of electricity for refrigeration, resulting in a ∼ 10% improvement on total energy-saving performance. This research work demonstrates the high potential of using the designed lighting-heating coupled TDDs system in buildings for both energy savings and daylighting benefits.