ABSTRACT
Of all agricultural production activities, the greenhouse industry is worldwide the fastest growing sector. There are two major reasons for this. First, the greenhouse separates the crop from the environment, thus providing some way of shelter from the direct inuence of the external weather conditions. This enables the production of crops that otherwise could not be produced at that specic location. Second, the greenhouse enclosure permits the manipulation of the crop environment. This asset allows the grower to steer the cultivation in a desirable direction. It leads to higher crop yield, prolonged production period, better quality, and less use of protective chemicals. The added value per unit surface area in greenhouse crops is much higher than that in open-eld cultivation. The downside of this intensication is that with current designs, greenhouse production has a higher demand per unit area for resources. In moderate climate zones, energy is needed, whereas in (semi) arid zones, the cooling and availability of water is of major concern. On the other hand, in view of the growing concern about sustainability, one has to realize that, after all, the greenhouse is a solar collector, and this will ultimately be another factor that will contribute to the growth of the greenhouse sector in the future.
