ENERGY EFFICIENT HEATING TECHNOLOGIES AND MODELS IN LEAN-TO CHINESE SOLAR GREENHOUSES: A REVIEW

In such cold area as north part of China, energy accounts for 65% of total greenhouse crop production cost. Therefore, it is of prime importance to reduce energy consumption for greenhouse crop productions. Technologies for reducing energy consumption in greenhouse crop productions can be classified into two categories. One is to design energy saving greenhouses with less energy demand and/or less energy losses, such as the lean-to Chinese solar greenhouses with north heat storage walls. The other is to employ energy efficient heating technologies, such as heat storage with phase change materials and heat pumps. In this paper, the recently developed greenhouse energy-saving technologies and their optimal design based on models were reviewed and discussed. Many studies have demonstrated that performance and design of heating systems can be improved by such models as computational fluid dynamics (CFD). Models are not only a useful tool for optimizing greenhouse design and energy saving systems, but also essential for well use of the new technologies.