Maintenance optimization incorporating lumen degradation failure for energy-efficient lighting retrofit projects

This study presents an optimal lighting maintenance plan that takes into account lumen degradation failure. In lighting retrofit projects, retrofitted lights fail over time mainly owing to burnout and lumen degradation failures. These failures result in a reduced illumination level and lower project savings if proper maintenance is not performed. Previous studies developed lighting maintenance plans by modeling lamp population decay due to burnout failure. In this study, we present an optimal lighting maintenance plan based on lumen degradation failure. The lumen degradation failure is modeled based on the statistical properties of degradation rates. By using the Kaplan-Meier method, the formulated lumen degradation failure is used to model the surviving population. The surviving population model is used to design an optimal lighting maintenance plan, which maximizes energy savings and minimizes maintenance costs. The effectiveness of the formulated maintenance plan is demonstrated by an actual residential energy-efficient lighting retrofit project implemented in South Africa. Results show that the proposed maintenance plan is more cost-effective than full maintenance.