Thermal performance of a novel double-glazed window combining PCM and solar control glass in summer

The integration of PCM into glazed envelope to enhance its thermal inertia has shown great energy-saving potential. However, this could bring indoor overheating in summer due to the insufficient heat insulation for solar radiation in pure PCM glazed units. This work proposed a composite double-glazed window incorporating PCM and solar control glass, and numerically investigated its thermal behaviors under sunny and cloudy conditions in summer of northern China. The effects of glass optical properties, involving absorption coefficient and refractive index, on the phase change cycling, indoor thermal comfort and building energy efficiency were analyzed. The results show that the increase of glass absorption coefficient facilitates the melting of PCM, but degrades the thermal comfort, even resulting in overheating risk on the sunny day. Moreover, as the absorption coefficient and refractive index of glass increase, the energy efficiency of PCM window equipped with solar control glass instead of general glass can be improved remarkably, and the influence of refractive index is more drastic than that of absorption coefficient. On the sunny day, the energy saving rate is 14.25% for the glass absorption coefficient of 160 m−1, which is 41.53% for the glass refractive index of 3.