A simulation study on CO2 concentration in protected cultivation

In protected cultivation in The Netherlands, it is common practice that CO₂ enrichment is supplied by the heating system. The improvements in glasshouse insulation achieved during the last decade decreased both the air exchange of the glasshouse and the heat demand. During periods of low heat demand and high irradiance, the cumulative effect is a decrease of the CO₂ concentration considerably below ambient. Moreover, even with open ventilators, certain climatological conditions may cause a marked decrease of the CO₂ level in the glasshouse.This paper presents some physiological aspects of the problem. With emphasis on the CO₂-concentration level, estimates of the production of a typical glasshouse crop were made, as related to climate control in early spring.Economic aspects of additional CO₂ supply (independent of the heat demand) are presented.