Influence of Angle of Rotation of Luminaires with Asymmetrical Luminous Intensity Distribution Curve on Calculated Photometric Parameters

Lighting systems often use square LED panels or spherical luminaires, which may not always have an exactly symmetrical luminous intensity curve, even if they appear to be symmetrical. A problem with these luminaires can already arise when measuring luminous intensity distribution curves in a photometric laboratory due to incorrect symmetry determination. For design reasons, many times it is very complicated or even impossible to determine the photometric axes of the luminaire in the case of both spherical and square luminaires. This fact may cause a difference in the angle of rotation of the luminaire in light design software and real lighting systems and thus can cause a situation that the lighting system does not meet the requirements of standard STN EN 12464–1. Such a situation is, of course, undesirable and can cause considerable financial losses. Considering the uncertainties of measuring the parameters entering the lighting system calculation and other influences that cause the difference between the calculated and measured parameters, it is necessary to oversize the system to a certain extent, but there is an upper limit defined by Act no. 555/2005 on the energy performance of buildings. This article deals with the problem that can be caused by an incorrect angle of rotation of the luminaire with an asymmetrical luminous intensity curve when installing the lighting system.