Selection of greenhouse design and technology options for high temperature regions

Greenhouse production facilities in Australia are located in regions which include temperate, subtropical and tropical climate zones. High (over 35degreesC) dry bulb temperatures are common for many of these sites and crops are potentially at risk. There are numerous options available to greenhouse operators to minimise or eliminate these risks. These environmental modification techniques can be broadly categorised as: greenhouse design (shape, dimensions and roof configuration), reducing solar load through shading and venting, forced air circulation and evaporative cooling. The selection of the most appropriate technique for both new and existing greenhouses is a challenge for many greenhouse managers who seek to operate profitable businesses in a market that currently provides only moderate financial returns. Whilst provision of adequate ventilation is well recognised, the characteristics and implications of some of the other techniques are not as well appreciated and understood. The criteria to be used in the selection of alternative cooling techniques have been identified and the performance of natural ventilation of greenhouses and fog cooling compared.