Validation of the EN 15193:2017 calculation method to estimate the daylight supply in a building: comparison with dynamic climate-based simulations

Abstract

This paper compares a simplified method to calculate the daylight factor and the annual daylight contribution in a space to the output of dynamic daylighting simulations. The simplified calculation method is the one implemented in the European Standard EN 15193 for the calculation of the energy demand for lighting in buildings, while the tool for dynamic simulations is Daysim (managed through DIVA-for-Rhino). The analysis was carried out by applying the two approaches to a reference office room, which was assumed to be located in different sites and having different window areas, with different orientations, both in the absence and in the presence of a mobile shade. The presence of an obstructing building was also considered. A total number of 108 cases was considered for the comparison. The results showed a very good correlation between the analytical method and the Daysim simulations to calculate the daylight factor (R 2 =0.99, with an absolute average difference of 11%). The correlation was lower for the calculation of the annual daylight contribution (R 2 =0.86, with an absolute average difference of 35%), due to the complexity of variables included (climate, orientation, presence of a moveable shade). Among the variables, the higher differences between the analytical and simulation results were observed for the climate and the absence/presence of a shade.

Energy Saving Generated Through Automatic Lighting Control Systems According to the Estimation Method of the Standard EN 15193-1

“…Accordingly, the LENI values and the potential savings could be different. On the other hand, if a different approach was used, for instance based on a dynamic simulation tool (such as DIVA-for-Rhino or SPOT) different results in terms of energy saving would be obtained [59].…”

“…The type of DLCS determines the FD,C value and then FD, while the occupancy control determines FO. A more detailed description of the features of the standard can be found in previous papers from the Authors [58,59].…”