Thermal performance of single span greenhouses with removable back walls

To improve the thermal performance of conventional single span greenhouses (SPGs), two types of greenhouses with removable back walls that are suitable for the climate in southern Jiangsu province, China were investigated, one with fully-removable back wall (FRG) and one with half-removable back wall (HRG). The removable back walls are made of jute fibre boards and installed in winter for heat preservation. They were removed in summer for ventilation. The thermal environment of the new greenhouses were studied experimentally. Results suggest the air temperature in the greenhouse with removable back walls could be maintained above 8.2 degrees C while the lowest temperature in the single span polyethylene greenhouse was only 2.9 degrees C, on sunny days in winter. During summer the highest indoor outdoor air temperature difference of the SPG was 9.0 degrees C whereas with the HRG and FRG they were 6.8 degrees C and 6.1 degrees C, respectively. No significant difference of heat release was found inside room between HRG and FRG. The removable wall combined with jute fibre boards represents a potential design improvement for the back wall of solar greenhouses. (C) 2015 IAgrE. Published by Elsevier Ltd. All rights reserved.