Experimental study to investigate the reduction of building cooling load by using the exhausted air from HVAC system combined with DSF system

Double skin façade systems are greatly used in buildings designed by famous architects and are described as a typical "green" building approach. The combination of the DSF system with the ventilation system has been widely used in recent years. In this study, the combination of the DSF system with the exhausted air from the heating, ventilation, and air conditioning (HVAC) system was investigated experimentally to show the performance of this system on cooling load reduction. The exhaust air from the HVAC system was passed through the DSF cavity to reduce the heat flow from outdoor to indoor and reduce the cooling load. The experiments investigated the effects of different airflow velocities (0.8, 1.2, and 1.5 m/s) on heat transfer in a controlled indoor environment. These velocities corresponded to 25%, 35%, and 50% of exhausted air. The results showed that both the airflow velocity and the width of the cavity had a significant impact on temperature distribution within the cavity. At air velocities of 1.5, 1.2, and 0.8 m/s, the cavity temperature was 19%, 15%, and 9.6% lower than the outer glaze temperature, respectively. The cavity temperature decreased by approximately 23%, 14%, and 8.7% for cavity widths of 0.35, 0.3, and 0.2 m, respectively. The best thermal performance was observed in the DSF system with a cavity width of 0.35 m. Comparing the reference and improved heat energy through the DSF cavity, there was a reduction in heat entering the indoor space, leading to a 17%, 23%, and 29% improvement in DSF performance for airflow velocities of 0.8, 1.2, and 1.5 m/s, respectively, with a cavity width of 0.2 m. Numerical analysis supported these findings and showed good agreement with the experimental results.