For the next few years millions of fluorescent luminaires will become waste and will be replaced by light-emitting diodes-LED luminaires. According to the Cost European Cooperation in Science & Technology Program, the next step will be shifting from sustainability to regeneration (enabling social and ecological systems to maintain a healthy state and to evolve); to reach this point, a is circular economy becomes necessary. The Technical University of Cluj-Napoca's Lighting Engineering Laboratory-LEL-is the main lighting independent consultant in Transylvania (the north-west region of Romania). For the Building Services Faculty, LEL adopted different energy efficient lighting solutions to replace existing fluorescent T8 luminaires. The best available techniques were evaluated over the last few years. Out of a range of different smart lighting control systems, LED were chosen and used for retrofitting the existing T8 luminaires or simply replacing them with new dedicated LED luminaires. The study analyzed five different lighting setups for upgrading the existing fluorescent T8 2*36W luminaires. One setup used T5 lamps and the others used retrofitted or dedicated LED lighting solutions. First the lighting quantities of each setup were evaluated under real and experimental conditions. Second, a programable power source was used for measuring power quality indicators corelated with the provided lighting outputs, under different voltage values and waveforms. For each lighting setup, an even and odd current harmonic limit check was performed in line with class C-lighting equipment, IEC 61000-3-2 requirements. A new energy efficiency and power quality indicator was proposed-the lighting apparent power density [VA/sq.m/100lx].Sustainability 2019, 11, 7125 2 of 15 halide lamps) need to be collected separately, due to their mercury content (a hazardous and water contaminant material).Worldwide, over the next few years, millions of fluorescent luminaires will become waste and will be replaced by LED luminaires. This has already occurred in some western and north European countries. Society is presently guided by a lighting linear economy-where all existing luminaires became waste and are replaced by new dedicated LED luminaires.Luminaries are generally nonlinear loads connected to the low voltage AC distribution network. Some light sources, like fluorescent lamps and LEDs, require a power supply system (ballast or driver) to interface them with the electric network. Generally, the current waveform contains some amount of distortion, depending on the luminaries' technology [7].However, as LEDs continue to replace incandescent and fluorescent lighting, there can be a significant impact on power distribution networks due to the non-linear nature of light emitting diodes. This paper will investigate the main power quality concerns arising from the use of LED lighting on our electrical networks. Further, it will also assess the impact of power quality disturbances on LED lighting technology [8].The Technical University of Cluj-Na...