MODULAR CONSTRUCTION OF CLOSED-LOOP PRODUCTION SYSTEMS

In the policy paper ‘Agricultural Structure’ (Braks, 1990) the Dutch government states that horticultural crops in greenhouses, for the greater part, must be grown in almost closed-loop production systems before the year 2000. At this moment there are no standards which these systems are required to meet. Therefore, the setting of these technical requirements has the highest priority in the research. The prerequisites, as stated in the policy paper ‘Agricultural Structure’, are translated into technical requirements, that are made independent of the crop grown on these systems.

The economic life-span of the closed-loop production systems can be increased by designing a durable and flexible system, which is geared to future developments. A solution for this, is to design standard-elements from which several types of production systems can be built. With the same elements a substrate-bed, an ebb-and-flow bed and a rolling bench can be built. This means that a system, such as an ebb-and-flow rolling bench, can be constructed from modules in several stages. One can start with growing in substrate-beds. These can be rebuilt into ebb-and-flow beds, which can be converted to ebb-and-flow rolling benches at a later date. This gives several advantages, such as:

• from a technical point of view: flexibility, due to the fact that several different systems can be built using standardized elements.
• from an economical point of view: low annual costs, due to the long life-span of the elements.
• from an environmental point of view: waste reduction.