The effect of outdoor climate conditions on passive greenhouse design.

摘要

The objective of this paper is to demonstrate the need for a generic design tool to adapt greenhouses to local climate conditions. To illustrate this need, we determined the effect of design parameters on greenhouse climate and crop yield of a passive greenhouse, for 2 different climate zones. The investigated climate zones were Mediterranean (Almeria, Spain) and equatorial highland (Addis Ababa, Ethiopia). Design parameters investigated in this research were: (1) the NIR transmission of the cover; (2) the ventilation area; (3) the heat capacity; and (4) the heat exchange coefficient of a passive heat storage facility. First, we developed a generic model to link the crop yield to the design parameters, through their effect on the greenhouse climate. Thereafter, the sensitivity of the greenhouse climate and the crop yield to the design parameters was analysed for the two greenhouse locations. Results show that the effect of a particular design parameter on greenhouse climate, and thus on crop yield, depends strongly on the outdoor climate conditions. For example, one percent increase of the heat exchange coefficient of the passive heat storage facility resulted in Ethiopia in a crop yield increase of 0.010% while in Almeria the crop yield was not affected. In conclusion, this work proves (a) that the greenhouse design should be based on the climatic context in which the greenhouse is going to operate and (b) that for each location different design parameters are important. These aspects should be taken into account when designing the greenhouse, resulting in a multi-factorial design approach. In view of this time consuming and complex design approach, there is a need for a generic design tool able to automatically perform the optimization of the greenhouse design parameters for each location.