Optimal design method for electrochromic window split-pane configuration to enhance building energy efficiency

Abstract

Electrochromic (EC) windows can prevent glare by adjusting their tinting state, but the tinted EC glass will affect the use of daylight in the room, resulting in the increase of lighting energy consumption. Splitting the EC window into several panes and tinting only a portion of them can effectively mitigate the conflict between glare prevention and the usage of daylight. However, there is a lack of design methods for EC window split pane configurations to realize further lighting energy-saving potential. To address this problem, this study proposed an optimal design method for EC window split pane configuration. This method is based on the glare calculation model and aims to obtain the minimum tinted area hours (TAH) of the EC window. Taking a south-facing EC window office building in Beijing as a case study, the effectiveness of the proposed design method was investigated by simulation. Results show the proposed design method identified the most energy-efficient and comfortable split panes scheme. By combining with the split-pane glare control method, 95.3% of intolerable glare was prevented, and a useful daylight illumination index of 73.3% was achieved. It also significantly improved building energy efficiency, saving 29.8% of lighting energy consumption compared to whole window design scheme. This study provides a promising design methodology for the high-performance application of EC windows in buildings.