This study is principally based on predicting the consequences on the microclimate of changing greenhouse design. Several variations on the greenhouse design have been described and examined, i.e. the number of spans and gutter height. Climate investigations were based on numerical simulations using the CFD model and included the dynamic effect of the crop on the flow as well as the subsequent heat and mass exchanges. The results show: (i) that the structural design elements, such as the height of the greenhouse and the number of spans, have significant consequences on climate performance; (ii) that we cannot indefinitely increase the height and the number of spans of greenhouses; (iii) that increasing the volume of the greenhouse raises heat requirements and thus the economic profitability of this kind of investment is debatable.