Evaluation on the thermal and optical performance of a double skin facade with a semi-transparent phase change material blind system

Phase change material (PCM) blinds integrated into the double skin facade (DSF) have been raised as a promising method to improve the thermal performance of DSF. However, previous studies mostly adopted opaque PCM blinds which may affect the light transmittance of the DSFs and indoor light environment. This study focuses on the evaluation of the thermal and optical performance of a semi-transparent PCM blind in DSF. Experimental study has been conducted in a test facility during different seasons in Shanghai, China. Temperature distributions and indoor diffuse radiation of the integrated DSF and semi-transparent PCM blind system with three blind tilt angles (30°, 45°, 60°) were analysed. The thermal performance of the semi-transparent PCM blinds and traditional aluminium blinds was compared on a typical day. Results show that the semi-transparent PCM blind can significantly lower the highest temperature in the DSF cavity in warm season, and reduce the temperature fluctuation range by 10 °C during the period of 9:00 am ∼ 21:00 pm. During cold season, the semi-transparent PCM blind was able to maintain a steady thermal zone for 4 h and 28 min, with temperatures stabilising at 15 ∼ 20 °C. The tilt angle of 45° demonstrates optimal thermal performance in both warm and cold seasons. The results also proved that the semi-transparent PCM blind with a 45° tilt angle contributes to a comfortable indoor light environment due to the better stability and longer duration of the diffuse radiation.