Summary

Climate Monitor is a generic platform for analyzing various plant processes, climate factors and keeping quality of greenhouse plants. The program is designed such that is allows easy integration of new analysis models and new sources of data. It has among others been used for analysis the optimal use of supplementary lighting.

Standard empty shell of the Climate Monitor.

The artificial light analysis is first of all based on a prediction model for estimating photosynthesis of greenhouse plants 24 hours ahead in time, and estimates the photosynthesis in 1 hour slot intervals. The predictive model looks at the parameters of the particular greenhouse, including glass factors, metal frame, shades and the power consumption and effect of artificial lights as well as temperature and CO2 levels from the climate control computer and local weather forecasts in order to estimate the changes in plant photosynthesis from turning the light on or off in the 24 hour period ahead in time. With the predicted levels of photosynthesis the data can then be analyzed to see if the desired photosynthesis sum can be met within the next 24 hours by natural means, and if not, the analysis will continue in the decision support part of the system.

Input parameters for the artificial light analysis module.

The decision support module uses local electricity market prices 24 hours ahead in time and the predicted photosynthesis data to make the decision when it is most cost-effective to turn on the artificial lights in the greenhouse. Seeing as the most common practice for greenhouse staff during winter is to use the artificial light to provide working light the module takes into account the work schedule of greenhouse staff to find any hours where the lights must be used. Conversely the module will also take into account the fact that greenhouse plants benefit from having several hours of complete darkness to be used for regeneration, meaning there are hours where the lights must not be used. With these considerations the periods of time in which the artificial light should be used are found.

The results of the analysis are displayed in Climate Monitor and shows the steps taken in the analysis from naturally occurring photosynthesis to artificial light assisted photosynthesis. The results are displayed in graphs as well as a summary explaining which hours to use the artificial light and the monetary cost for doing so.

Steps 1,2 and 3 taken in an example analysis.

Future improvements

Structure the artificial light analysis module for user decision making. Make it possible for the user to decide an arbitrary combination of rules that should in the analysis and allow for decisions being made during the analysis when special conditions are met. Make the set of results customizable.
The analysis only looks at which hours during the day the artificial lights should be used. Lowering the time slot interval to shorter periods of time makes for finer control of the artificial light and saves money.
Need testing on the accuracy of the photosynthesis prediction model by turning the artificial light on and off at the times determined by the analysis and then checking the recorded climate values the day after to see the difference in predicted and actual photosynthesis.
The photosynthesis prediction model can be further refined. Some values used in the model are assumed to be constant while in real life are not, such as the CO2 level in a greenhouse.