Jesper Mazanti Aaslyng

IntelliGrow: a greenhouse component-based climate control system

Abstract 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.

Climate control software integration with a greenhouse environmental control computer

Abstract To integrate dynamic model based climate controlling in real-time with an environmental control computer a system integration interface—BipsArch—was developed. The three main objectives were: (1) to supply standard routines for communication with the environmental control computer. (2) to establish a set of databases to represent the current informational environment for the greenhouse. (3) to formulate a language capable of defining the working concepts of greenhouse process control. Experiments were performed to test this interface concept over a four month period simultaneously at two locations. During this time BipsArch managed the data flow between the greenhouse environmental control system and the modeling software.

A sensor for microclimatic measurement of photosynthetically active radiation in a plant canopy

A photosynthetically active radiation (PAR) sensor has been described and tested, the sensor is so small that it can be placed directly on a leaf in the canopy. It is inexpensive to produce and several can be used in the canopy at the same time to obtain realistic measurements of irradiance distribution. Its characteristics satisfy the PAR sensor requirements, and correlation to a standard commercial sensor is better than 0.97. Spectral response, cosine relationship, stability and calibration are described, as well as its construction and electronics.