Impact of heating location, forced ventilation and screens on the energy efficiency and condensation risks inside a cucumber greenhouse.

Abstract : In the West of France, greenhouse cucumber production is largely developed. Heating makes it possible to maintain a high level of production, but with high energy costs. Growers therefore try to implement new crop management practices to increase the energetic efficiency while keeping good productivity and quality. In this prospect, two treatments were tested considering two greenhouse compartments (307 m2): one with heating tubes at the upper limit of the canopy and a thermal screen (control) and the second one with heating tubes at low position inside the canopy, mechanical ventilation (5 volumes h-1) and thermal + shading screens (innovative). These compartments were equipped with sensor chains, each with four pairs of temperature and humidity probes at four levels. Additional thermocouples measured fruit temperatures. The energy consumption of the compartments was also assessed. Measurements were conducted over a three-month period of time. Results show that a better homogenization of the distributed climate was reached inside the innovative treatment. Also, the innovative treatment made it possible to significantly reduce risks of condensation on fruit compared to the control. Finally, in the innovative compartment, the energy efficiency was notably increased compared to the conventional management, generating the same yield, but saving 17% of the energy. The innovative crop management therefore demonstrated the benefits of the fans combined with low level heating and double screens.