Temporary control of climate screens in growing crops responsive to day length is carried out so as to obtain a specific length of days. Shading can also be used with the strong solar radiation to protect plants from UV and / or to reduce the air temperature in the greenhouse. They can also act as a thermal insulation curtains (energy efficient). With such use should be shut screens always after sunset, when the outside temperature falls below the value at which included heating.
The day usually shading are drawn when the intensity of solar radiation exceeds the level set by the gardener of radiation - that is, one that can cause burns or growth of plants in the greenhouse air temperature above the optimum temperature for photosynthesis. Radiation level at which the crop should be shaded, can be determined using the data stored in the computer change from earlier days. For example, suppose that the upper limit of optimal air temperature is 25°C. The data collected are to be found radiation levels at which the air temperature rose above 25°C, because at this value is assumed shading. If the computer makes it possible to close screens prostate, are further steps should be such as to maintain the optimal temperature, while the least shading the plants. If there is no danger of burns or excessive plant growth temperature in the greenhouse, we should never raise screens in the day, as it is a reduction in yield.
The big problem with the programming of each device is working properly placed sensors that measure climate parameters under which to operate these devices. This applies especially to the work screens when radiation causes heating of the plant. As the optimum temperature for photosynthesis, the temperature should understand that "feel" the plants, and that the intense radiation is generally higher than air temperature. The best solution is to control screens based on readings from sensors measuring the temperature of the plant - which, unfortunately, in Poland it is rare - and not air.
In measuring the air temperature is important to place the sensor height. At low plant is placed over the plants, and at high - among them. With some computers can work climate, two or more sensors in a greenhouse. In this situation, one should be placed above the tops of plants, and the rest of the stags.