Development of a thermal model for simulation of supplemental heating requirements in Chinese-style solar greenhouses

The simulation model CSGHEAT has been developed to estimate the hourly heating requirements in a Chinese-style solar greenhouse. The heating model was developed based on the heat balance of greenhouse air. With the set indoor temperatures, the surface temperatures of the floor and north wall were estimated by solving ordinary differential heat balance equations. The model is relatively easy to use because the model does not need to input measured data such as solar radiation like other models, and most of the heat sources and sinks in the Chinese-style solar greenhouse are included in the model. The model was validated with experimental data, and the predicted result was found to be in good agreement with the measured data. The mean difference between the measured and the estimated ground temperature is about 1.4 degrees C, and 1.8 degrees C for the north wall. The average percent error and relative root means square error (rRMSE) value for hourly heating prediction are 8.7%, and 11.5%, respectively. Therefore, the CSGHEAT model is considered to be sufficiently accurate and a reliable tool for researchers and others in the greenhouse industry to assist in designing and analyzing supplemental heating requirements in Chinese-style solar greenhouses.