Application of Artificial Neural Network for the Optimum Control of HVAC Systems in Double-Skinned Office Buildings

Abstract

Double Skin Façade (DSF) systems have become an alternative to the environmental and energy savings issues. DSF offers thermal buffer areas that can provide benefits to the conditioned spaces in the form of improved comforts and energy savings. There are many studies conducted to resolve issues about the heat captured inside DSF. Various window control strategies and algorithms were introduced to minimize the heat gain of DSF in summer. However, the thermal condition of the DSF causes a time lag between the response time of the Heating, Ventilation, and Air-Conditioning (HVAC) system and cooling loads of zones. This results in more cooling energy supply or sometimes less than required, making the conditioned zones either too cold or warm. It is necessary to operate the HVAC system in consideration of all conditions, i.e., DSF internal conditions and indoor environment, as well as proper DSF window controls. This paper proposes an optimal air supply control for a DSF office building located in a hot and humid climate. An Artificial Neural Network (ANN)-based control was developed and tested for its effectiveness. Results show a 10.5% cooling energy reduction from the DSF building compared to the non-DSF building with the same HVAC control. Additionally, 4.5% more savings were observed when using the ANN-based control.The window factor is one of the main factors that increase the building energy consumption due to high U-value and solar heat gain. To solve this issue, many studies have been conducted on high-performance windows, smart windows, and shading systems in both industry and academic fields. Energy reduction through the Double Skin Façade (DSF) system has been verified by previous studies [3][4][5][6][7][8][9][10][11][12][13][14][15][16]. If a DSF system is installed in a building, the building has additional space, and it works as a thermal buffer. Through the thermal buffer, window heat loss is reduced in winter. Window heat loss is calculated by multiplying the U-value of the window, the area of the window, and the temperature differences between indoor and outdoor air. With the installation of the DSF system, the outside condition of the building is changed from the weather condition to the indoor air of the DSF system, which has a higher temperature than outdoor air in winter. Through these temperature differences, window heat loss is reduced with the installation of the DSF system. In summer, on the other hand, window opening control is needed to reduce cooling energy consumption by ventilating the hot air inside the DSF system to the outside [3].Many researchers have conducted studies related to energy saving through DSF system installation. Yoon et al. analyzed heating energy savings by the installation of the DSF system in a high-rise apartment at different floor levels in Seoul, which is a heating dominant area. Results show that the first-floor apartment unit consumes the least heating energy, and the 25th floor consumes the most [4]. Joe et al. analyzed the impact of the DSF design, regarding g...

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