Thermal performance and airflow analysis of a new type of Double Skin Fasade for warm climates: An experimental study

Double Skin Facades (DSF) integrated with shading devices are increasingly implemented in tall buildings to protect buildings from excessive solar radiation. However, the overheating in the cavity of DSF leads to a lower thermal performance in hot seasons. This study introduced a new type of DSF called Interstitial Slat-blind DSF (IS-DSF) featuring wind-induced ventilation and insulated shading devices. This research aims to highlight the capabilities of the proposed DSF in a warm climate and identify contributing environmental and geometrical factors for overheating risk reduction of IS-DSF. To this end, an experimental study was conducted in a scaled room located in an outdoor environment on summer days in Brisbane, Australia. First, the test room with and without IS-DSF was studied to assess the performance of IS-DSF for controlling indoor temperature. Next, a parametric evaluation was conducted including geometrical variables (cavity width, slat blind angle) and environmental factors (approaching wind speed and direction, air velocity in the cavity and solar radiation). It was found that the most influential factor for controlling the cavity overheating risk tends to be the air velocity inside the cavity while the effect of blind slats angle is negligible. A threshold for airflow velocity in the cavity was estimated beyond which the overheating of the IS-DSF in the cavity becomes negligible. Correlations were also established for IS-DSF with different lateral openings' widths to predict cavity airflow ve-locity. Overall, IS-DSF showed a reduction in surface temperature adjacent to the air cavity as a potential advantage over conventional DSFs for reducing the common overheating risk in the cavity of DSF in a warm climate.