New method to design better greenhouses

Doctorate student Bram Vanthoor of Wageningen UR Glastuinbouw has developed a method of calculation to design greenhouses better suited to local circumstances. The method has been tested for the Netherlands and Spain. During the tests two different greenhouse designs were built fully in line with the local situation. The method offers the possibility to optimise greenhouse building worldwide. Vanthoor will defend his thesis on Friday 17th of June.
Arch greenhouses, parral greenhouses, Venlo greenhouses and wide roof greenhouses, the variation worldwide is enormous. When designing a greenhouse one must also choose between a large number of different construction elements, such as e.g. roofing materials, heating and cooling systems. Which kind of greenhouse the grower chooses and how the greenhouse is being fitted is amongst other things, dependent upon the outside climate, economic factors, legal issues, social circumstances and the presence of sources, such as water, energy and CO2. The choice in favour of one possibility very often has a direct influence on the other elements and also depends on the plants to be cultivated in the greenhouse. This makes it very difficult to optimize the design process.

Optimization design
Bram Vanthoor developed a design method, which dependent on the local climate and economic conditions, designs a greenhouse which supplies the maximum financial result. The method always includes local circumstances and takes eight design elements into consideration, namely greenhouse construction, roofing material, outside awnings, chalk materials, energy screen, heating system, cooling system and CO2 quantity dosing system.

The design method is based on three models, namely one greenhouse climate model, one plant model and an economic model. These models calculate, dependent on the variables supplied, the financial result. After that an optimalisation-algorithm adjusts the design step by step. In this way the financial result is maximised finally and the best greenhouse found.

The design method has been tested in Spain and in the Netherlands. The model was designed quite differently for both locations, but with realistic proposals for the most successful greenhouse in both instances. The Spanish greenhouse had a larger ventilation area and was specially built to prevent high temperatures, whilst in the colder Netherlands a higher working capacity and an energy screen were fitted. It became clear at both locations, that the economic performance of the greenhouse improves by a high percentage of light passing through and that an outside screen, geothermic heating and mechanical cooling make the result worse.

Perspective of the method
The method has in first instance been developed for tomatoes. Adjustment for other
plants is possible. The design method of the greenhouse can assist in optimizing the cultivation of plants in greenhouse further. It is also possible to establish the best location to build new greenhouse with the new approach and the results of the economic changes on the cultivation can be predicted. Bram Vanthoor in the meantime lives and works as a business developer for a horticultural supplier in Mexico. The acquired knowledge is used there to adapt greenhouse to the local conditons.

Source: Fresh plaza
Published on: 6/20/2011