The special design of the green house light

Daylighting design of solar greenhouse light

Sunlight is not only an indispensable energy for photosynthesis of green plants, but also the main heat source of solar greenhouse. Therefore, when designing a solar greenhouse, we should first solve the lighting problem of the greenhouse and maximize the transmission of sunlight to the interior of the greenhouse.

Solar greenhouse light in northern China are mainly used in winter, spring and autumn. In winter, the height angle of the sun is low, the sunrise is in the southeast and the sunset is in the southwest. Therefore, in order to maximize the use of sunlight in winter, solar greenhouses mostly adopt the orientation of north facing south and east-west extension.

Practice has proved that the outside temperature is very low in winter morning. After the grass curtain is opened in the morning, the indoor temperature often decreases significantly. The orientation of the solar greenhouse should be West as far as possible, which is conducive to prolonging the illumination time in the afternoon and heat preservation at night. It should be 5 degrees to the west, not more than 10 degrees.

When the incident angle of light increases from 0 degrees to 40 degrees, it has little effect on the transmittance of transparent materials. The reflection loss rate of light quantity is only a few percentage points; When the incident angle changes from 40 degrees to 60 degrees, the transmittance decreases significantly with the increase of the incident angle; When the incident angle is greater than 60 degrees, the transmittance decreases sharply. Therefore, the incident angle of 40 degrees or the projection angle of 50 degrees is the critical point affecting the transmittance of transparent materials. In the early stage of the development of solar greenhouse, the daylighting angle with the maximum projection angle of 50 degrees from the sun to the daylighting surface of the greenhouse on the winter solstice is determined as the reasonable daylighting roof angle.