Light loss factors for sports lighting

This article describes an empirically derived light loss curve and Total Light Loss Factor (LLF_T) for sports lighting applications. An empirical model was developed by comparing the illuminance from initial design computations against measured illuminance, on a point-by-point basis, for 37 sport fields. The study was limited to lighting systems that employ 1500W metal halide lamps with a rated life of 3000 hours. The model, which is based on more than three thousand measurements and an equal number of computed data points, demonstrates that values for LLF_T of 0.75, 0.69, and 0.65 are representative of real-world sports lighting applications at 1200, 2100 and 3000 hours, respectively. The model suggests that it would be pragmatic to use a LLF_T of 0.69 as part of the design calculations for new sports fields. This recommendation is markedly different from the common practice of using a LLF_T of 0.80.