Influence of the calculation grid density to the resulting photometric parameters of public lighting

Abstract

Calculation and measurement of performance parameters of public lighting are performed in a grid of points defined by the CIE publication 140 [1] and European standard EN 13201-3.[2] Calculation grid defined in these documents was created at a time of less powerful computers and less precise measuring technology. Distance between two adjacent calculating points may be even 3 m, depending on the geometry of the road. This arrangement is too sparse in view of the fact that presently used computers can cope with much more denser grids in a shorter operation time and the measurement can be performed by luminance analyzers with more accuracy as well. Between the results of the calculation with different grid densities of calculation points there can be significant differences. This fact can be influenced by new optical systems and some LED luminaires which, as it was found out by measurements, may contain various local extremes in the LIDC. When calculating the performance parameters of public lighting with given grid density these extremes may fall between calculation points and thus they are not included in the calculation. The solution is to propose a new density of calculation points which would be designed with respect to current possibilities of computer and measuring technology. The paper deals with the influence of grid density to the resulting photometric parameters of public lighting. In computing software, calculation grid of points according to EN 13201-3 and calculation grid with half and 2 to 10-times densification of calculation points will be used in order to capture the impact of given local extremes to the resulting parameters using luminaires with different optical systems. The results of these calculations will be used as the basis to determine an appropriate density of calculation and measurement grid. The results will be used in the preparation of future revisions of normative documents, which provide a method for determining points of calculation and measurement grid.