Solar greenhouse construction belongs to the discipline of facility agriculture engineering, which is about high yield and high efficiency. However, due to the unbalanced and insufficient development of agriculture, the uncoordinated development between urban and rural areas, low level of investment in agriculture, severe talent shortage, and many other factors, the modernization of facility agriculture has been seriously stalled, making it a "low-lying land" in today's economic and social development. Most solar greenhouses are built by experience or blindly borrowing methods from others due to the constraints of traditional and primitive building materials, construction methods, and economic conditions, as well as the lack of architectural thermal theories, advanced technical methods and the application of new materials and technologies. As a result, these solar greenhousesareriddledwith problems including poorly designed structures,poorthermal performance, low land utilization, and poor control of the light and heat environment, which make it difficult for traditional greenhouses to meet the conditions to grow warm-season vegetables and fruits during winter nights, leading to frost damage and pest attack. In addition, these greenhouses are not suitable for mechanized operation due to their poor structure, resulting in low yield rate and poor economicperformance, and making farmers feel discouraged. To address this issue, Prof. Chen Chao's team has been working hard to respond toissuesrelating to agriculture, farmers, and rural areas and the rural revitalization and agricultural modernization strategy. With the research objectives of significantly improving the land utilization rate, solar fraction, and capability of light and heat environment control of solar greenhouses, the team carried out a systematic, in-depth and comprehensive innovative research in the theories and methods of modern solar greenhouse building technologies, standardized building design technologies, new phase change material technologies, high-performance solar thermal utilization technologies and engineering implementation methods, and developed a set of "long chain" high-performance solar phase change heat storage solar greenhouse technology system which can adapt to regional climate.

The technology hasmadethe following four contributions. First, the heat transfer mechanism of solar greenhousesthat adapt to regional climate and can maintain production with low energy consumption and high efficiency throughout the year has been revealed, a thermal design theory of solar greenhouse building has been developed, and a new method of high-performance solar greenhouse building design has been proposed. Second, a high-performance GH-20 cement-based composite phase change heat storage material, and a preparation and molding process have been invented. Third, a series of preparation and industrial production technologies for high-performance multi-surface condenser and multi-tube solar air collector that adapted to solar greenhouses have been developed. Fourth, based on the phase change heat storage, condenser-based air collector and wall ventilation technologies,astandardized design technology system for solar greenhouses adapted to regional climate has been developed.

The research results have been employed to guide the constructionandrenovation of more than 60 high-performance demonstration solar greenhouses in Beijing, North China, Northwest China and Jiaodong. Compared with traditionalsolargreenhouses, the land utilization rate of a single solar greenhouse has increased by more than 30%, and the yield of overwinter production ofwarm-season vegetables and fruits with high economic value has increased by more than 20%. The cumulative area of land with the coverage of related technologies has reached 1,775 mu (about1.18 km2), bringing about more than 4.61 million yuan of economic benefits. Between 2018 and 2020,the completion unitsand application unitshavewitnessed additional sales of 169.31 million yuan and an additional profit of 22.47 million yuan. The implementation of this project, the construction of demonstration bases, and the training of key technologies can help improve theconceptand level of solar greenhouse construction technology in northern China, promote the standardized design, construction, operation and management of modern facility agriculture, raise farmers' awareness of modern production,and increase employment andrevenue.