Ventilation performance of a naturally ventilated double skin façade with low-e glazing

Abstract

Natural ventilation through double-skin façades shows promising effects in building energy saving, but the possible potential and behind mechanisms with low-e glazing remain to be explored. To fill the research gap, this study compared the normal clear glazing and the low-e glazing in the use of a naturally ventilated double-skin façade (NVDSF), together under impacts of spectral optical properties, environmental factors and configurations. Results reveal a significant enhancement - 13% more ventilation rate by replacing clear glass with low-e glass. However, the ventilation performance is sensitive to low-e glazing’s spectral optical properties, where a higher portion of absorptivity is more advantageous for natural ventilation. Besides, environmental factors - solar incident angles and solar intensities - show predominant impacts on ventilation performance, which are correlated in the form of power functions. Results suggest that NVDSFs with small incident angles (<40°) is better. At similar trends, the NVDSF performance is also better under solar intensities larger than 600 W/m2. On the other hand, configurations of NVDSFs also exert primary influences. The optimal cavity gap is found ranging between 0.15–0.3 m, and the ventilation rate increases until a vent height of 0.4 m. This study demonstrates that a significant improvement in ventilation efficiency can be achieved simply by changing the glazing type.