A new metric for optimal visual comfort and energy efficiency of building lighting system considering daylight using multi-objective particle swarm optimization

Abstract

In the past, an optimization-based control strategy of lighting in a building only focused on maximizing energy efficiency in which the results of the visual comfort of occupants is decreased at the minimum level. Therefore, a visual comfort metric model that integrates the artificial lighting and daylighting is crucial to be developed, so that the model can be simultaneously treated with energy performance model in the control strategy for equal performance of energy and visual comfort. This paper proposes a new visual comfort metric model called illuminance uniformity deviation index (IUDI) that reflects illuminance uniformity and the index is considered as an objective function in the optimization-based control, based on a simulation-based study. The proposed IUDI is optimized simultaneously with power demand using multi-objective particle swarm optimization (MOPSO) to find the best compromise solution. The IUDI with MOPSO is implemented in an actual office room by considering mixed artificial light and daylight. Based on the comparative results with the coefficient of variation of root mean square error (CVRMSE), the proposed IUDI showed superior performance in two aspects: (1) technical - improved 6% and 27% of visual comfort and energy savings, respectively and (2) economic - reduced a simple payback period of 28% and a net present value of 33%. The proposed IUDI is a great tool for a new visual comfort metric that satisfies the EN 12464-1 (illuminance level is 500 lux and uniformity is 0.6). Moreover, it also has a practical value to be implemented in green buildings.