Introduction: The field of daylighting in buildings is a poorly researched topic. The lack of daylight has proven negative impact on health and well-being of individuals. In order to improve visual comfort in the indoor environment of buildings, an evaluation instrument should be designed in order to assess the influence of daylight on users’ well-being and health. Purpose: With the master’s thesis we wanted to evaluate visual comfort in the indoor environment of the chosen room, and design an assessment instrument (i.e. questionnaire) for evaluation of the connection between the daylight and its effects on users’ health and well-being. Methods: Using bibliographic databases, we performed literature review in the four fields of microclimate with the emphasis on visual comfort. In the lecture room 213 at the Faculty of Health Sciences of University of Ljubljana (from March to June 2016), we performed illumination measurements at 16 working places. At the same time, we monitored users’ behaviour (monitoring adaptation of working environment to the available daylight). The research included 15 students of the 3rd year of the programme Sanitary Engineering. We also designed simulation model of the subject classroom and presented the illumination using the pre-set conditions. In regard to the established, we designed the assessment instrument that was filled-in by the users for the purpose of validation. Results: The field of daylight is poorly researched topic locally and abroad. Researches have not yet developed an assessment instrument to determine influence of the daylight on users’ health and well-being. Average illumination measurements on five working places out of sixteen totalled to less than 500 lx. At the working places next to the windows, average measured illumination values were higher, namely from 1431 to 4260 lx. Illumination decreased with the depth of the place. Illumination values in simulation model and mainly cloudy weather coincided with measurements, but were lower. Discussion and conclusion: Number of researches in the field of visual comfort is low, but it has been increasing. By measuring illumination, we identified working places with low daylight. Those were mainly the working places the furthest away from windows. Users did not adjust shades in order to improve visual comfort. Based on the results, we designed an assessment instrument, which can be used in further researches. On the basis of that, it will be possible to prepare recommendations for users of how to achieve visual comfort and healthy environment.