The effect of the analysis grid on daylight simulations with climate-based daylight modelling

The recent development of climate-based daylight modelling (CBDM) practice led to various methodologies to perform daylighting evaluations, while its insertion in new guidelines created the need of common procedures and verified frameworks. This paper aims to give an insight into the relation between the analysis grid and time-step settings and the reliability of an annual climate-based daylight simulation performed with distinct methods. CBDM is a rapidly evolving practice, and the evaluation reflects that by including several different state-of-the-art software tools in the overall comparison. The space under analysis is a real case study classroom where the monitoring of the luminous environment is being conducted for a parallel research. The results, expressed as annual exposure, Useful Daylight Illuminance (UDI) and Daylight Autonomy (DA), show a good agreement between most of the tools and delineate some minimum requirements on the input accuracy for the considered space, in terms of grid resolution, time step and sky vault discretisation.