Three-dimensional simulation of light spectrum and intensity within an LED growth chamber

•The accuracy of the simulations were high with R2 between 0.901 and 0.997.•The model could simulate spectral micro-light climate in different directions.•The model was capable of determining the optimal placement of LED modules.•The model gave useful guidelines for light uniformity to be used in chamber design. An increased knowledge of different light spectrum on plant structure and physiology is required for improving horticulture production and energy efficiency. This implies a high number of experimental repetitions under uniform and reproducible light conditions. The objective of this study was to create a virtual LED chamber to be used for functional structural plant modelling and for exploring the optimal chamber design regarding light conditions. The spectral light simulations were evaluated in six heights and seven directions with measurements performed in a real LED chamber. The accuracy of the simulations compared to measurements were high with R2 between 0.901 and 0.965 with data from different heights and R2 between 0.959 and 0.997 with data from different directions. The mean absolute percentage errors between measured and simulated light intensity in different directions were 12.7%, 2.8%, 8.9% and 30.6% for light in the blue, green, red and far-red wavelength ranges, respectively. MAPE from data in different heights were within the same range and showed consistent tendencies between colors. The model was capable of evaluating the light intensity in different directions and uniformity at different heights. Thus the chosen GPUFlux model in GroIMP can be used to simulate micro-light climate within an LED growth chamber for functional structural plant modelling and to assist in optimizing chamber design and LED placement for uniform and reproducible light conditions.