IntelliGrow: a greenhouse component-based climate control system

A new greenhouse climate control system has been constructed with the objective of decreasing energy consumption while maintaining. or even increasing, plant production. The system is based on the use of mathematical models for estimating the absorption of irradiance, leaf photosynthesis and respiration. The model builds on a general leaf model that with a few modifications can be used for different greenhouse crops. The temperature, which was controlled according to the natural irradiance, was allowed to vary considerably more than in a standard climate. Under low light conditions, energy use was reduced because the temperature was lowered. In contrast, when irradiance is higher, the plants seem able to utilize both a higher temperature and CO2 During nighttimes the temperature was lower than in standard climate. The thermal screens were used according to a screen simulation system. The system balances the energy costs saved via isolation against the production loss caused by the decrease in irradiance. A six-month trial of the system resulted in energy savings ranging from 8% in late spring (April-June) to 40% in early spring (March-May). During the winters 1997-98 and 1998-99 the accumulated energy savings per season varied between 20% and 38% at two different locations in Denmark. (C) 2003 Published by Elsevier Science Ltd.