Abstract
Sunlight greenhouse is a typical energy-saving greenhouse widely used in north China. This type of greenhouse has only one transparent roof facing to south direction and solid walls in direction of north, east and west. Those walls and the floor soil play a roll as a heat storage during daytime, and those stored heat and the thermal curtain on the roof allow to keep the inside environment adequate for crop growth without or with less supplemental heating during night in winter season. In this study, a basic model is developed to simulate thermal environment of the sunlight greenhouse without crop, using energy and mass balance equations. The validation of the model is performed with the measurement data at the sunlight greenhouse of China Agriculture University (CAU) in Beijing. The greenhouse air temperature, relative humidity and other temperature of the greenhouse components are generally predicted well except the north wall, whereas the partial opening of the film to prevent overheating causes unexpected change of ventilation rate and then discrepancy between predicted and measured value during the daytime. Secondary simulation is also carried out varying the number of air exchange at several intervals and the result shows that the model may have further accuracy by introducing proper air exchange rate.
