Summer performance of a naturally ventilated double-skin facade with adjustable glazed louvers for building energy retrofitting

Facade energy retrofitting marks an important step toward a low-carbon building industry. As a highperformance building envelope, the double-skin facade is increasingly applied to existing buildings with proven effectiveness. To improve energy efficiency and solve the lingering overheating problems in summer, a new type of double-skin facade (DSF) integrated with adjustable glazed louvers is proposed. Experimental investigations were conducted in a Chinese city with a typical temperate continental climate, covering basic configurations, thermal optimizations, operation strategies, and energy performance. The study demonstrated that cavity ventilated and interior ventilated configurations perform best during daytime and nighttime, respectively. The open configuration of the external skin improved the daytime cavity ventilation by leveraging wind pressure instead of thermal buoyancy. It also allowed cavity height to be lowered, giving DSF the prospect of application to buildings with low floor-to-floor height. While tilted louvers reduced cavity ventilation, they avoided reflecting sunlight into the room and gaining heat. The tilt angle proposed is equal to the noon solar altitude angle in late summer. During the nighttime, the louver skin significantly improved indoor ventilation, but a reasonable way to open internal windows is also needed. Additionally, switching between different configurations based on the dynamic, localized temperature thresholds maximized climate responsiveness and indoor comfort while minimizing cooling loads. Compared with the conventional design, the optimized louver-type DSF delivered significant energy savings of 11.9% and 5% in summer, daytime and nighttime, respectively, successfully reducing the overheating risks. (c) 2022 Elsevier B.V. All rights reserved.