Assessment of building daylight systems considering sunscreens under real conditions of the sky

Introduction. Lighting engineering is a complex scientific field which requires the generalization of knowledge in visual comfort evaluation, design and architectural solutions as well as in other areas including the humanities. Global ecological problems and the drive for Sustainable Development require achieving maximum energy efficiency from architectural designers. The tasks of designing daylight systems under real sky conditions cannot be solved without considering the problems of insolation and sunscreens. Russian and foreign standards cover long-put questions about the need to improve the daylight calculation method considering additional light reflected from adjacent surfaces under the clear and partially cloudy skies. The objective of the study is analysis and improvement of the daylight system calculation method considering sunscreens under intermediate sky conditions. Materials and methods. The methods of searching and selecting relevant literature in international abstract databases with well-developed tools for thematic search as well as analytical methods are described. Results. A method for calculating daylight system considering sunscreens under the intermediate sky conditions is suggested. The analysis of the obtained formulae confirmed the proposed theory: under the influence of direct sunlight, reflection from adjacent surfaces significantly increases the daylight level in a room. Conclusions. Assessment of daylight in a room under the intermediate sky conditions should take into account a reflection of the direct sunlight. Correcting the problem under conditions of the CIE overcast sky model in the calculation is associated with the availability of a light climate database. This approach makes it possible to formulate the criteria for a dynamic daylight assessment. Combination of an artificial lighting system with an automatic control mode guarantees the requirements of indoor illuminance and energy saving.