Growers can change a lot of settings in the greenhouse process control computer. These settings finally result in the desired greenhouse climate. Consequences of these settings in terms of energy use are often not clear.
Optimal control can calculate how a desired climate in the greenhouse can be realised in an energy optimal manner. The grower can define the desired climate by setting bounds for temperature, RH, and CO2. Also the maximum amount of available CO2 can be specified. The optimal control system then determines, based on model calculations, the minimal amount of energy, ventilation, and CO2 injection that are needed to realise the desired climate.
In the figure it can be seen that the greenhouse air temperature (a) does, indeed, stay between the bounds. The negative energy input means active cooling (b). Ventilation windows are closed as much as possible to keep CO2 inside the greenhouse.
The proposed method gives more insight to the grower on the energy that is needed to create the desired climate. In general, energy can be saved by changing the bounds and giving the system more freedom. At this moment, further analysis will be done on the analysis of the optimization results.
This research is part of the project 'Optimal management of energy resources in greenhouse production systems' and is supported by the Dutch Technology Foundation STW. Besides Wageningen UR, also Hortimax B.V., Lek/Habo B.V., and Boonekamp Roses B.V. are involved in this project.