Using a wireless sensor network to determine climate heterogeneity of a greenhouse environment

One of the main targets of a greenhouse control system is to generate a uniform climate environment, which has obvious economic advantages, due to homogenous crop, lesser diseases and the potential energy saving. By using a dense wireless sensor network, the spatial distribution of climate parameters and thus the uniformity of greenhouse environment can be determined. This information can be used by the growers to detect cold and wet spots in greenhouse environment and to adjust their climate control system. In this study, the horizontal climate heterogeneity of the greenhouse environment is analysed. Six experiments were performed in commercial greenhouses observing the micro-climate with 100 wireless sensors under different conditions and for different crops. From the data the spatial and temporal distribution of air temperature T and relative humidity RH was obtained. Instantaneous spatial differences varied up to ±5°C for T and ±20% for RH, depending on location, time of day and season. Significant differences of ±2°C for T and ±12.5% for RH, while averaging data over longer periods (5 days), have been observed. Further research is needed to investigate the way the information regarding the spatial and temporal distribution of climatic parameters can be integrated in the control systems and finally to quantify the energy saving potential.