Cost-benefit analysis of lighting retrofits in grocery stores: a case study of İstanbul

This study presents a comprehensive feasibility analysis of LED lighting retrofit projects, examining their technical, economic, and lighting quality aspects based on empirical data collected from 53 grocery stores in Istanbul. The research methodology involves a comparative analysis of pre- and post-retrofit data on energy consumption (kWh), illuminance levels (lx), and investment costs. A key aspect of the analysis is the classification of projects into two primary categories—'Savings-Oriented' and 'Comfort-Oriented'—to investigate the relationship between the investment payback period and the gains in lighting quality. The results of the analysis indicate that the transition to LED technology yielded an average net saving of 37.4% in lighting-related energy consumption. In addition to energy efficiency, a significant improvement in visual comfort was achieved, with average illuminance levels increasing from 513 lx to 1,232 lx, representing an overall illuminance gain of 193%. The cost-benefit analysis reveals distinct outcomes based on the primary objective of the retrofit: the 38 projects classified as 'Savings-Oriented' achieved a highly efficient average payback period of 28.3 months, whereas the 15 'Comfort Oriented' projects had payback periods exceeding 60 months. This latter finding is substantiated by an exceptional illuminance gain of 309% in this group, confirming that the priority was the enhancement of lighting quality over a rapid financial return. Ultimately, this research empirically demonstrates that LED lighting retrofits in the grocery retail sector represent a financially feasible and technically successful investment that can be tailored to align with distinct strategic priorities, whether a rapid return on investment or an enhanced customer experience.