Design methodology and thermal performance of passive energy-saving agriculture greenhouse

Chinese-type solar greenhouse (CSG) enable sustainable winter vegetable production without external heating, yet 30 percent of CSGs face safety risks from suboptimalr design methodologies. This study classified three design methodologies: thermal insulation (CSG Ⅰ), solar transmittance (CSG Ⅱ) and solar interception (CSG Ⅲ), and conducted a two-year comparative evaluation of their thermal performance. The feasibility of unheated overwintering production in extreme cold environments was verified through comprehensive experimental and numerical methods. The solar interception methodology provided the suitable thermal environment, and increased the land utilization. During overwintering production, CSG Ⅲ increased indoor temperature by almost 5–9 °C, reduced winter humidity by 7–11 percent, and reduced CO2 concentration by 22–42 percent. The solar radiation capture was increased by 5–13 percent. The internal temperatures of back wall and soil were increased by 38 % and 30 %, respectively. The solar interception methodology realized the basic requirements for the unheated production where the lowest temperature was −28 °C. This optimized design addresses key limitations in current CSG systems through its novel solar interception strategy, demonstrating significant potential for energy-saving winter vegetable production in high-latitude cold regions.