Integration of intelligent building envelope techniques as a system to Improve Thermal Performance of Multi-story Buildings in the Hot Dry Climate of Khartoum

Abstract

The recent concept of thermal performance improvement attracted all the researchers and building architects to switch over from the present practice of mechanical systems to environmental methods of performance improvement methods in an efficient modern way. This study has employed performance analysis tools, namely Energy Plus, CFD, and Grasshopper with DIVA plug-in. The research was carried out on a theoretical office building is a rectangular-shaped ten-story building designed as an open plan office with a surface of 552m2 and height of 4m. This research focused on improving the performance of the building façade, double-skin facade technique was used as a tool to improve the thermal performance, where a detailed analysis of its thermal behavior and performance in hot-dry climate for the best and most effective DSF alternatives was carried out. Thermal modeling was carried out on three DSFs alternatives (shaft type, corridor type, and combined shaft-corridor DSF type) in comparison with the base case single-skin facade, and well-designed single-skin facade (WSS). The simulation results showed, the total cooling load has been reduced by 5% in the well-design single-skin facade, 15% in the combined shaft-corridor DSF, and by almost 4.4% and 7% in the shaft and corridor types, respectively. And then further investigation possibilities to improve the thermal performance level by applying the two techniques have been conducted (airflow promotion and convective heat transfer reduction). Firstly, investigation possibilities to improve the office airflow by modifying the combined DSF configuration system have been conducted. The strategies include; modifying openings size, shaft height, and cavity depth, where the following findings are tabulated (A DSF system with openings vs. cavity depth. As the opening size increased, the performance improved with the same cavity depth, A DSF system with the opening size vs. shaft height. Increasing the shaft height improved the thermal performance and as the shaft height increases, and DSF system cavity depth vs. shaft height. As the shaft height increases, the cavity depth should be decreased with a constant opening size). Secondly, the effect of convective heat transfer reduction techniques like orientation, shading devices, and glazing properties are studied. For a PMC blind angle of 80 degrees with high slops comparatively and close to external glass skin, the convective heat transfer for the inner environment due to solar radiation is only 28% of the heat transfers for the case without blinds. According to simulation results, an orientation slightly east of south (typically 15° east of south) is expected more effective in Al-Khartoum city. Also the total cooling load has been reduced by 12% in the Body tinted green glazing and by almost 26% in the Reflective glazing active blue. Finally, the simulation results showed the thermal performance improved by 24.12% when implementing the modified double-skin facade system.