This study proposes the assembly and tuning of an inexpensive lighting control system composed of light sensors, Light Emitting Diodes (LEDs), and microcontrollers, for automatic control of artificial light (AL) in a vertical farm greenhouse depending on natural light (NL) conditions. The developed system falls within the scope of sustainable controlled environment farming as a solution for improving energy efficiency and plant productivity. The work was developed in a Raiz Vertical Farms facility in Lisbon, introducing tailored control of light intensity and duration to enhance lighting energy performance in plant production. The developed system provides daily AL complements after sunset to deliver predefined Daily Light Integrals (DLI) targets under various NL conditions. "Pluto" basil plants were grown under different DLI targets of 12.5, 15 and 17.5 mol.m-- 2 .d- 1 delivered by a mix of natural and artificial light during 4 weeks in September/October, revealing varied yields and LED energy consumptions. For the DLI regimes of 12.5, 15 and 17.5 mol.m-- 2 .d- 1 , plants showed average pot (i.e. three plants) fresh biomass of 35, 32.5, and 47.5 g and total LED energy consumptions of 4.48, 12.43, and 13.75 kWh, respectively. Considering the total number of plants that could be equally illuminated under the same LED capacity, the potential LED specific energy consumptions of 1.64, 4.90, and 3.71 kWh.kg-1- 1 are obtained for regimes of 12.5, 15 and 17.5 mol.m-- 2 .d- 1 . The first was the most energy efficient, with lighting needs met 16 % by AL, however, the latter showed feasible energy performance with added benefits in basil yield.
