Gradients of temperature and relative humidity of air in greenhouse with wireless sensor network

Abstract

The distribution of temperature and relative humidity of air is one of the factors that influence the uniformity of crop growth in greenhouse. The heterogeneity of these elements distribution was evaluated in a greenhouse with different combinations of mechanical and natural ventilation, in Campinas (SP, Brazil). A wireless sensor network with nine SHT75 transducer spatially distributed and a meteorological station were used to measure the internal and external environment, respectively. In the closed greenhouse, there are strong vertical gradients in temperature and relative humidity of air. When the exhausters are turned on and the greenhouse is allowed to ventilate, transferring the thermal energy with external environment, these gradients decrease. When the greenhouse is ventilated only via mechanical ventilation, the temperature and relative humidity gradients are larger than those observed with roof ventilation associated with mechanical ventilation.