A methodology for model-based greenhouse design: Part 1, a greenhouse climate model for a broad range of designs and climates

Abstract

With the aim of developing a model-based method to design greenhouses for a broad range of climatic and economic conditions, a greenhouse climate model has been developed and validated. This model describes the effects of the outdoor climate and greenhouse design on the indoor greenhouse climate. For use in a greenhouse design method that focused on the optimisation of a set of design elements, the model should fulfil the following three requirements: 1) predict the temperature, vapour pressure and CO2 concentration of the greenhouse air, with sufficient accuracy for a wide variety of greenhouse designs under varying climate conditions, 2) include the commonly used greenhouse construction parameters and climate conditioning equipment, and 3) consist of a set of first order differential equations to ensure that it can be combined with a tomato yield model (of a similar structure) and to allow the use of ordinary differential equation solvers. The dynamic model was validated for four different greenhouse designs under three climatic conditions: a temperate marine climate, a Mediterranean climate and a semi-arid climate. For these conditions, the model accurately predicted the greenhouse climate for all four designs without modification of the model parameters (except for one case). In more than 78% of the cases, comparison of simulations and measurements of the indoor climate yielded a relative root mean square error of less than 10%. Given these results, the model is considered to be sufficiently accurate and sufficiently generic to be used for developing a model-based greenhouse design method.