SE—Structures and Environment: Optimal Light Integral and Carbon Dioxide Concentration Combinations for Lettuce in Ventilated Greenhouses

Abstract

Carbon dioxide enrichment and supplemental lighting in greenhouse facilities are common procedures for improving production rates. Carbon dioxide enrichment is usually used to decrease the amount of supplemental lighting, as it is a much less expensive process. However, it is economically prohibitive to maintain elevated CO2concentrations inside the greenhouse during periods of high ventilation rates. In this work, a crop-specific model is developed for lettuce. The model searches for the economically optimal daily light (photosynthetically active radiation—PAR) integral and CO2concentration combinations. This takes into account the ventilation rate, the environmental PAR integral, and the acceptable values of target combinations of PAR integral and CO2concentration, for the specific crop plant (lettuce). The optimal combinations achieve operating savings for the greenhouse facility.