Extended Methodology for Calculating the LENI Coefficient with a Reactive Power Component (LENIQ) in the Analysis of Energy Efficiency of Building Lighting

The article presents an extended methodology for calculating the LENI energy efficiency index for building lighting, taking into account an additional reactive power component—LENIQ. The proposed methodology takes into account the influence of the power factor (cos φ), the nature of the receivers, and the presence of constant lighting intensity (CTE) systems. Based on the analysis of two public buildings (schools)—one without a photovoltaic installation and the other equipped with a PV system—it was shown that reactive power can be a significant component of the energy balance. For the facility without PV, a value of LENIQ = 58.4 kvarh/m2·year was obtained, while for the facility with PV—4.75 kvarh/m2·year, which indicates a more than tenfold reduction in reactive energy thanks to the use of automation and renewable energy sources. A comparison with model values for different cos φ enabled an additional assessment of the efficiency of lighting installations. The aim of this study is to develop an extended methodology of the LENI indicator by introducing a reactive power component LENIQ, enabling a comprehensive assessment of lighting energy efficiency.