Sunshine is an indispensable energy source for green plants for photosynthesis, and it is also the main thermal source of sunlight greenhouses. Therefore, when designing the sunlight greenhouse, we must first solve the lighting problem of the greenhouse, and limit the sun to the greenhouse.
The sunlight greenhouse in northern China is mainly used in winter, spring and autumn. The height of the sun in winter is low, the sunrise is southeast, and the sunset is in the southwest. Therefore, in order to limit the use of the sun in winter, the sunlight greenhouse mostly uses the position of the northern dynasty and the extension of east and west.
Practice has proved that the external temperature in the winter morning is very low. After the straw curtain is opened in the morning, the indoor temperature often decreases significantly. The position of the sunlight greenhouse is as good as westward, which is conducive to extending the light time and night insulation at night. It is suitable for 5 degrees west, and it should not exceed 10 degrees.
When the light incident angle increases from 0 degrees to 40 degrees. The influence on the transparent light transparency of transparent materials is not large. The reflection loss rate of the amount of light is only a few percentage points; when the incident angle changes within 40 degrees and 60 degrees, the transmittance of light transmission is transmitted. The increase in the angle of the rate shows a significant decline; when the incident angle is greater than 60 degrees, the light transmission rate shows a sharp decline. Therefore, a 40 -degree incident angle or a 50 -degree projection angle is a critical point that affects the transparent materials light transmittance. In the early days of the development of sunlight greenhouses, the projection angle of the winter solstice and sunlight lighting surface of the winter solstice reached 50 degrees of lighting angles as a reasonable lighting roof angle.
