Development and performance evaluation of a hybrid louver window system using natural light and LED for energy-efficient vertical farming building

This study developed a hybrid louver window system (HLWS) that integrates window, natural light and LED technology to address the high electricity consumption and cooling energy due to heat generated by LED use in vertical farming buildings. The HLWS comprises transparent double glazing, a diffuser, and multiple horizontal slats within a louver air cavity, which effectively transmit natural light indoors and distribute it to achieve the required amount of light. The system dynamically adjusts the LED intensity based on real-time variations in natural light to maintain the target photosynthetic photon flux density. Vents installed at the upper and lower parts of the window system expel excess heat generated by the LED and solar radiation in tropical climates. The system's electricity consumption and cooling load, resulting from LED heat production, were evaluated using a full-scale mock-up facility. It was experimentally verified that the developed HLWS system not only reduces the electricity consumption of LED by increasing the use of natural light but also reduces the cooling load by reducing the operating time of LED in vertical farm buildings. The total energy consumption of vertical farm buildings with the HLWS was 31.6 % less than those without the HLWS.