| The solar greenhouse is a kind of new-type greenhouse with distinct Chinese characteristics, which is used by the masses of peasant's users. The energy-saving solar greenhouse can work naturally without heating in winter and has popularized at North, Northwest and Northeast in China. Greenhouse introduction should consider the weather characteristics of local area and combine local weather advantages with the structure of the greenhouse to meet local production. If unsuitable greenhouse structure and relevant technology are introduced blindly, they can cause energy waste and bring low productivity effect.The improving Yiyou type solar greenhouse of Shouguang area in Shandong was introduced totally to the area of Fengxian and brought indoor crops freeze injury in a continuous cloudy weather with low temperature. To resolve this problem, the author determined greenhouse internal and external temperature, illumination, indoor soil temperature, etc. environmental factors via experiment to understand the daylighting and heat preservation of local greenhouses. The data analysis shows light transmittance of membrane drops because of much dust and accordingly the daylighting quality of local greenhouses on cloudy day is relatively bad. The soil temperature indoors is low in the daytime on cloudy day, influencing crops to grow. The heat preservation at fine night is worse than that at the cloudy night. The minimum temperature indoors is about 5℃, lower than the temperature of crops' growing lower limit. The production management of local greenhouses is relatively bad. Because of unventilating in time, the maximum temperature indoors goes beyond 35℃ in the daytime, far higher than the temperature of crops' growing upper limit. At the same time cover or take off heat curtain has no unity of standard, too early or too late will influence heat preservation of greenhouse at night and the photosynthesis of the crop.According to the local greenhouses' current situation and the heat preservation principle of solar greenhouse, the author took measures such as adding PPC foam board to back wall, digging cold-proof ditch, choosing heat curtain with strong warm performance, determining suitable time to cover or take off covering curtain, strengthening productionmanagement, etc. Experiments had been done to verify the result of above measures, indicating that warm and light environment indoors has been improved obviously. The result shows light transmittance of local greenhouses has been improved by about 20% on sunny day and by 6% to 10% on cloudy day. The minimum temperature indoors has been improved by 4~6 癈 and the maximum temperature indoors does not exceed 28 癈. The temperature change is in the crop necessary range. According energy balance and plural return, author derived the math formula to determine suitable time of covering or taking off heat curtain, changing the method used to determine time by experience in the past. Concrete time given by math formula can increase the photosynthesis of the crop furthest and improve heat preservation of greenhouse at night.In order to demonstrate the improvement result of local greenhouses and determine time to cover or take off heat curtain online, the author developed the micro-climate simulation program of solar greenhouse in Fengxian. This program, which is written by MatLab 6.1, mainly facing the production administrator and technician of greenhouse, can be used to not only show the performance of greenhouse to the visitor, but also instruct the administrator to work actually. The program mainly demonstrates heat preservation, daylighting of solar greenhouse and the calculation of covering or taking off heat curtain time. It adopts the graphical display, directly perceived through the senses succinctly. According to the needs of user input and output, the interaction is strong.
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