A technique of adaptive control of the temperature in a greenhouse using ventilator adjustments

Abstract On-line statistical time series analysis provides a means of adaptive control of the temperature in a naturally-ventilated greenhouse. The non-linear relationship between internal temperature in a naturally-ventilated greenhouse. The non-linear relationship between internal temperature and ventilator aperture depends on the external air temperature, wind velocity and solar heating. A linear time series formula with variable parameters can be closely fitted to successive samples of aperture and internal temperature data and used to predict the ventilator adjustments that maintain the required temperature. Starting with an equation for the heat balance in a greenhouse it was first shown that the adaptive control should be superior to proportional plus integral control with fixed parameters. It was later confirmed that the analysis and control were applicable to a real greenhouse, and some improvements to the control algorithm were introduced.