A unified framework for evaluating UV-C sources: introducing the cost of germicidal energy (CGE) metric

The selection of UV-C light sources for disinfection and treatment applications involves consideration of performance, efficiency, lifetime, and cost. This paper introduces a novel performance metric - Cost of Germicidal Energy (CGE) - designed to provide a standardized framework for comparing UV-C sources across different technologies and both technical and economic parameters. CGE integrates key parameters, including radiant power, germicidal effectiveness (based on wavelength and spectral power distribution), energy consumption, source lifetime, and cost. By quantifying the cost per unit of germicidal energy delivered, CGE enables easier comparison and application-relevant assessment of different solutions. This metric is particularly valuable for guiding technology selection and system design in surface, air, and water disinfection applications. The paper presents a comparative analysis of conventional mercury-based UV-C lamps applications and emerging UV-C LED technologies. While mercury lamps have long been the industry standard, they face increasing regulatory and environmental challenges. In contrast, UV-C LEDs have advanced rapidly in recent years, with significant improvements in wall-plug efficiency, spectral targeting, operational lifetime, and cost reduction. The forward-looking roadmap for UV-C LED development is outlining projected milestones in performance and affordability. These projections are supported by recent record-setting prototypes and experimental data, demonstrating the accelerating pace of innovation in this field.