Development of a realistic model to accurately predict the ‘mirrored S-curve’ nature of LED luminaire lumen maintenance for any operating conditions

In the current era, LED lighting technology is the most widely used illumination source in all applications worldwide. Accurately predicting lumen degradation and lifetime performance has become critical for ensuring long-term reliability and cost-effectiveness. Traditional models often fail to capture the complex, non-linear nature of real-world degradation behavior. The work systematically models the lumen degradation behavior of LED luminaires using a four-parameter double exponential Gompertz function. The proposed model effectively captures the asymmetric, mirrored S-curve behavior observed in long-term degradation profiles of LED luminaires, which traditional exponential models fail to represent accurately. Experimental data from accelerated degradation tests conducted on three different commercial 16W LED luminaires were used to develop the model. The SEM-EDS analysis identified silver mirror tarnishing as a dominant physical degradation mechanism, providing material-level insight into the observed steep lumen drop during mid-life operation. A key contribution of this work is the development of a predictive framework that correlates proposed model coefficients with temperature using only three accelerated degradation tests. This enables accurate estimation of lumen maintenance performance at untested operating conditions, significantly reducing the need for exhaustive physical testing. The proposed methodology provides a practical, scalable, and cost-effective solution for predicting LED lifetime, making it highly applicable to both research and industry.