Energy sustainability performance of a sliding cover solar greenhouse: Solar energy capture aspects

A new-type of Sliding cover Energy-saving solar Greenhouse (SEG) has been developed. It is addressing several structural problems of traditional solar greenhouses, mainly energy capture and balance features. At northern latitudes, solar irradiance in wintertime is limited, which, along with extreme low outside temperatures, raises many energy sustainability issues. Capturing incident energy primarily depends on south-facing shape and cover transmittance characteristics, and this paper sets out an analysis framework for heat gain, leaving out other heat balance conservation factors (insolation). A circular shape has been selected for the SEG and is compared to Liaoshen-type Solar Greenhouse (LSG) that uses an elliptical south shape, used in traditional Chinese solar greenhouses. The SEG replaces passive north wall heat storage of LSG with active heat storage in water, thus creating an advantage in stored energy management. The shape factors and aperture efficiencies of the two designs were analysed and experimentally assessed during typical clear-sky days in four seasons. This provides a theoretical basis for structural and environmental optimisation. The design of SEG moved the ridge forward and increased the lighting roof angle, resulting in better solar radiation capture for winter sun altitudes. The newly-introduced SEG design exhibits better winter energy capture and less summer cooling load and features, by construction, and better performance in many other aspects, including potential automatic intelligent management actions. In addition to the SEG's energy capture analysis, along with briefing on light and temperature superiority, the design may also compensate for its higher constructional cost by superior automation capacity that calls for a combined holistic intelligent solution and offers many operational sustainability advantages. (C) 2018 IAgrE. Published by Elsevier Ltd. All rights reserved.