Impact of environmental factors on energy balance of greenhouse for strawberry cultivation

Abstract

This study elucidated the effects of passive solar greenhouses on strawberry cultivation in temperate areas. The energy required to heat the greenhouse was calculated. Furthermore, the results of a field test performed in a temperate area in central Japan were presented. Environmental conditions such as the ambient temperature, solar radiation, and relative humidity were experimentally investigated. The results of this study indicate that the maximum temperature difference between the inside and ambient air temperatures was 16.4 °C during the evaluation period. The maximum reduction in solar radiation through a transparent vinyl sheet in the greenhouse was approximately 30% when compared with the ambient solar radiation. Additionally, heating requirements were estimated to achieve optimal cultivation conditions in the future. The monthly heating requirement of the greenhouse was between 60.0 and 327.6 MJ/(m2･month), and the energy requirement for heating was found to be maximum in the extremely cold month of January. The energy required for controlling the optimum environment for sensitive plant cultivation was proposed. The proposed evaluation methods can also be applied to other regions for cooling.