Post-implementation evaluation of urban street lighting using LED lighting units: a multi-criteria decision analysis methodology

Abstract

Global shifts towards LED street lighting aim to prioritise energy efficiency and cost reduction. Still, systematic post-implementation evaluations that integrate heritage preservation, cultural sensitivity, and morphological diversity remain underrepresented in the scientific literature, particularly in Mediterranean heritage urban contexts where organic medieval architectural forms, UNESCO heritage classifications, and traditional cultural practices create implementation complexities absent in modern, architecturally designed environments. This study provides a comprehensive post-implementation assessment of the conversion of street lighting to LED across five distinct urban contexts in terms of form and culture in the urban centre of the municipality of Central Algiers, Algeria, where an integrated methodology based on the Analytic Hierarchy Process (AHP) and Geographic Information Systems (GIS) was developed and documented, designed explicitly for heritage-sensitive assessment. Data collection involved systematic protocols that included field light measurements in accordance with EN 13201-4:2015 with modifications for irregular heritage forms, structured expert assessments using documented AHP frameworks that achieved a consistency ratio of 0.07, culturally adapted community surveys, heritage-adjusted lighting energy consumption index (LENI) calculations according to EN 15193-1:2017, and spatial analysis using Moran's I with Monte Carlo substitutions. The study revealed significant contextual sensitivity in LED integration with the urban form, with the latter accounting for 44.5% of the variance in implementation success. It demonstrated that setting a uniform colour temperature of 4000 K led to fundamental incompatibility in heritage contexts, with a dissatisfaction rate of 73%, directly contradicting the pedestrian-preferred range, which was empirically verified at 2,700-3,200 K. Energy performance showed significant reductions ranging from 35.6% to 48.2% across contexts, resulting in annual savings of €287,000, although heritage-sensitive areas sacrificed 20-30% of theoretical efficiency to preserve cultural identity. Spatial analysis revealed a strong spatial correlation with formal predictors, including street width, pattern regularity, and proximity to UNESCO-listed sites, which significantly influenced integration results. This research presents a rigorously documented AHP-GIS framework for heritage-sensitive evaluation of LED lighting, demonstrating that the €125,000 investment in appropriate colour temperature is economically justified by enhanced cultural preservation, in line with global best practices for heritage lighting, and that it achieves payback periods of between 7 years.