sunlight greenhouse

Daylighting Design of Sunlight Greenhouse

Sunlight is an essential energy source for green plants to carry out photosynthesis, and it is also the main heat source for solar powered smart greenhouses. Therefore, when designing a solar greenhouse, the first step is to solve the lighting problem of the greenhouse and maximize the transmission of sunlight into the interior of the greenhouse.

The solar greenhouses in northern China are mainly used in winter, spring, and autumn. In winter, the solar altitude angle is low, with sunrise in the southeast and sunset in the southwest. Therefore, in order to maximize the use of sunlight in winter, solar greenhouses are often oriented in a north-south and east-west direction.

Practice has proven that the outside temperature is very low in winter mornings After opening the grass curtain in the morning, the indoor temperature of the eastern greenhouse often drops significantly. It is better to position the solar greenhouse towards the west as much as possible, which is beneficial for extending the afternoon light time and keeping warm at night. It is advisable to be 5 degrees west and not exceed 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 is only a few percentage points; When the incident angle varies between 40 degrees and 60 degrees, the transmittance shows a significant downward trend with increasing incident angle; When the incident angle is greater than 60 degrees, the transmittance shows a sharp decrease trend. So, a 40 degree incident angle or a 50 degree projection angle is the critical point that affects the transparency of transparent materials. In the early stages of the development of solar greenhouses, the maximum projection angle of the sun on the greenhouse's lighting surface on the winter solstice day, reaching 50 degrees, was set as the reasonable lighting roof angle.