Performance of a novel internal insulation in Chinese solar greenhouse for the cleaner and energy-saving production in high latitudes and cold regions

Chinese solar greenhouse (CSG), which facilitates year-round vegetable cultivation without energy consumptions or carbon emissions, is significant for sustainable agriculture. However, the overwintering production is often damaged by frost in high latitudes and cold regions. Since as much as 60% of the heat is lost from the front roof, a novel internal insulation was proposed to improve the thermal insulation capacity of the unheated CSG. The traditional single-layer front roof was transformed into comprehensive external and internal thermal insulation to reduce nighttime heat dissipation. The mathematical model and the energy balancing equations were established to clarify the theoretical basis and evaluated the effectiveness of the proposed method through experiments. The results indicate that the internal insulation helped reduce the heat loss of the front roof by 13.67% and the total heat saving in CSG was 8.75%. The average indoor temperature was improved by 2.01 K, and the difference with outdoor temperature could reach 36.26 K. The economic benefit 36.93 USD per day for winter production. The results can provide scientific evidence for the system design of internal insulation in solar greenhouses or other agricultural settings, in order to guarantee the cleaner and energy-saving production of annual vegetable supply in high latitudes and cold regions.