One of the main challenges in visual comfort assessment is controlling daylight in indoor spaces. The effect of daylight’s contribution to total light is one of the variables influencing how people perceive illumination in an indoor environment.

This paper aims to define a new metric “day-light-to-total light ratio (DTR)“ for assessing the contribution of natural and artificial light in the indoor environment and the optimal DTR which delivers the most satisfaction with the lighting environment.

This study examines additional factors that affect the lighting environment in indoor spaces, such as window characteristics and the impact of seasons on the defined acceptable DTR range.

To determine how occupants evaluate the f daylight ratio in their offices, a survey combined with the onside measurement of physical lighting quantity as an evaluation method was conducted in a real space following a long-standing interaction between the user and the building.

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