High quality artificial lighting of public places is one of the necessary functions of sustainable cities. It is much more than just providing sufficient light intensity with reduced energy consumption and low environmental impact. The solution to this challenge is not only technological, but also requires the consideration of the subjective approach, such as psychological, sociological, and aesthetic-functional. The article presents the SEC (Suitable for everyone, Environmentally-accepted, Cost-effective) methodology and model, which are placed in the context of sustainable city lighting. A holistic assessment approach of user environmental perception, priorities, and spatial responses is required to evaluate the impact of artificial night illumination. Lighting efficiency was expressed as the correspondence between environmental perception and spatial utilization during day and night. Ten sites with different urban background and illumination characteristics were selected. It was assumed that artificial night lighting influences the perception, priorities, and responsiveness of users. The validity of this argument was demonstrated at a relevant statistical level of p <0.05. The research results provided useful information about the current state, which is needed to prepare a sustainable lighting strategy, and could be compared between different or similar sites. Based on the obtained results, it can be concluded that the artificial lighting of urban open spaces is of high quality when the difference in the spatial perception and spatial utilization between day and night is as small as possible.
