In smaller sized greenhouses, a manual system opened and closed by hand could possibly be installed. These work easiest when the screen material is backed by a track system.
Start time – when in the morning will the display screen system start operation
Stop time – when in the afternoon will the screen system stop operation
Light level – at what light intensity will the screen end up being activated either to open up or close
Maximum/minimum temperature – what exactly are the limitations of temperature desired
Maximum/minimum humidity – What exactly are the limitations of humidity desired
Gap positions – this sets the percent open or close position under different conditions such as in early stages a winter early morning to lessen thermal shock or during the summer to provide better shading. The gap steps and speed of movement can be controlled in a few systems.
Time delay – under changeable weather conditions this avoids frequent starting and closing
Wind speed – To lessen heat loss, the screen could be closed early below high wind speed conditions
Snow detection – this can open the display and turn on heat when it starts to snow.
The typical system uses nylon monofilament or stainless steel rack drive for greenhouse china cables to aid the screen materials. The screen material can either rest along with the network of cables or be suspended by hooks from the cables. A gearmotor powers a drum or rack and pinion that moves the leading edge of the screen material. Control can be either with a manual switch or electronic controller.
Based on the over, the grower is required to enter the following parameters in to the controller:
A weather station is required to provide outdoor light level, temperature, humidity, wind and rain or snow conditions.