Qualifying lighting remodelling in a Hungarian city based on light pollution effects

The public lighting system has been remodelled in several Hungarian cities. In some cases the majority of the old luminaries were fitted with high pressure sodium lamps and they were replaced with white LED lighting with a typical correlated colour temperature of about 4500 K. Therefore, these remodelling works provide a testbed for methods in measurements and modelling. We measured the luminance of the light domes of selected cities by DSLR photometry before and after the remodelling. Thanks to the full cut off design of the new lighting fixtures we obtained a slight decrease even in the blue part of the sky dome spectra of a tested city. However, we have to note that this positive change is the result of the bad geometry (large ULR) of the previous lighting system. Based on Monte Carlo radiative transfer calculations we provide a comparison of different indicators that can be used to qualify the remodelling, and to predict the possible changes in light pollution. - Highlights: • Changes of the skydome of a Hungarian city were measured after lighting remodelling. • The observations were compared with Monte Carlo radiation transfer calculations. • Photopic measurements demonstrate improvement in light pollution after remodelling. • However, blue rich lighting increases the risk of negative ecological effects.