Field test and analysis of microclimate in naturally ventilated single-sloped greenhouses

The greenhouse is a modern agriculture technology that is widely used to provide a favorable microclimate for vegetable growth when an open field is inappropriate for cultivation. Field tests were conducted to test diurnal variations of temperature, relative humidity, and solar radiation and to analyze the microclimate characteristics in naturally ventilated single-sloped greenhouses of different sizes. The results showed that indoor air temperature and humidity under natural ventilation varied from 28.9 °C to 25.8 °C and 96% to 84%, which illustrates that ventilated greenhouses are able to create a favorable self-maintained, energy-balanced environment for vegetable growth. Moreover, it was found that a greater height and shorter span facilitates heat preservation and energy saving in single-sloped greenhouses. In addition, the relationship between the incident solar radiation and indoor air temperature was determined. This study provides a reference for further research to reduce energy consumption and achieve a favorable greenhouse microclimate, leading to higher product quality, improved yield and shorter cultivation time in single-sloped greenhouses.