Definition of a composite index of glazing rooms

Abstract

The effect of geometrical parameters of rooms and window openings on the value of the daylight factor (DF) in the reference point on the work surface is considered in the article. This is important, as while using a light factor (LF) and a window-to-wall ratio (WWR), there is a significant error. Therefore, there are objective difficulties with the unification of the results of studies on the effectiveness of natural sidelight, which are due to the influence of the size of the room on the DF value in the reference point on the work surface. The use of the above-mentioned coefficients to evaluate the efficiency of lateral natural light results in the fact that, at constant value of the coefficient, the value of the DF may differ several times. This is because the area of the window opening does not correspond to the area of glazing through which daylight passes into the room. The area of the room does not correspond to the area of the work surface on which it is necessary to provide normalized illumination, and the dimensions of both the room and the work surface are not taken into account in the LF or in the WWR at all. It is proposed to use a composite room glazing index (CRGI). It takes into account not only the glazing area of the window opening but also the dimensions and area of the work surface. This makes it possible to use the results of studies on the effectiveness of natural light without binding them to the dimensions of a room. Using the Relux program, the DF value in the reference point for rooms of different sizes with different glazing areas of the window openings is calculated and the dependence of the DF on the CRGI has been obtained. As a result of the approximation of this dependence, an equation describing the relationship between these quantities has been developed. An algorithm that takes into account both the width of the opaque portion of the window opening and its proportion has been developed to determine the area of the window opening at which the required value of the DF in the reference point is provided. The obtained scientific result in the forms of the CRGI and algorithm of calculating the area of the window opening is interesting from the theoretical point of view. From a practical point of view, the results help calculate the minimum glazing area of the window opening to provide a normalized DF value with a standard deviation of 0.894, based solely on the dimensions of the room. This is a prerequisite for using the obtained results in the development of normative documents for construction sites.