Screening

Screening & shading: managing light & energy

Smart climate screens are essential for optimizing greenhouse conditions. For instance, energy-saving screens can cut energy use by as much as 47%, while light-diffusing screens ensure the most effective spread of natural light within the greenhouse, thereby enhancing both yields and product quality. Complete blackout screens allow crops as Chrysanthemum and Cannabis to be on the correct night-day cycle. In short, there are screen types for any appliance and mechanisms to open and close them.

Control over light, energy & climate

There are three basic functions that screening fabrics are designed for. Selecting the right screens and using them wisely allows you to manage light, energy and climate. Control over light is the primary function and can be broken down into light transmission, light diffusion and blackout.

Light Control

Shading
Keeping intense sunlight and heat out of the greenhouse with shading screens. These screens often have aluminium incorporated into the fabric, and mostly serve a double function as energy saving screens during night time.
Diffusion
Screening is a perfect way to create diffusion when desired. Light diffusion screens scatters the light, eliminating shade and thus allowing light to penetrate deep into the crops.
Blackout or Light Deprivation
Eliminating the influence of light is also a possibility. Whether this is to control the length of the day, or to prevent light pollution towards neighbours and nature. Screening fabrics have been developed to eliminate all light transmission.

Energy Saving

Closing screens prevents conditioned air to leave the greenhouse or simply to rise to the top of the greenhouse. Conditioned air is brought to the desired temperature and humidity with energy. Keeping this heated or cooled air at the place where it is needed will save a lot of energy.

Climate Control

By making the screen properties work for you by opening and closing the screens, the climate can be controlled. Screens can be opened partially to allow warm, moist air to ventilate. Shading can prevent temperatures to reach undesired heights, but can also be used as a diffuse cloud.

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Screening Mechanisms

There are four different mechanisms in the field of greenhouse screening. For horizontal screening, the mechanics for opening and closing the screens are different. In vertical screening, there are two types of motors that can be used: tube motors and regular motors that turn a tube.

Horizontal Screening

Push-Pull screen system

In the push-pull system, the screen system is operated by rack and pinion gears and push-pull tubes. These are connected to the screen profile that is pulled between the trusses. The diabolo wheel brackets ensure the guidance of the push-pull tube.

The push-pull system exerts less force on the side walls, which is an advantage when working with multiple screens, beacause this allows for a lighter structure.

Pull-Wire screen system

In the pull-wire system, a drive tube with tension sleeves and steel cables that are wound and unwound, provides the horizontal movement of the screen profile between the trusses. The cloth resting on the wire bed is mounted to the screen profile that moves between the trusses to open or close the screen.

The advantage of the pull-wire system is that it intercepts less light than the push-pull tubes of the push-pull system.

Vertical Screening Systems

In the greenhouse gable, side walls, and interior walls, vertical (rolling) screens can be used. In side walls, the roller screen can serve multiple functions, such as sun protection, energy saving, and blackout functions, or to limit light emissions. With a vertical screen, in combination with a horizontal top screen, a more constant temperature can be achieved in the greenhouse, due to the insulating properties of the screening fabric.

Vertical screens are driven by a rolling tube that rolls up the screen fabric. For the different lengths and heights of the systems, the rolling tube mostly differs between Ø 50mm and Ø 63 mm. Roller tubes are available in single-groove and double-groove versions. In the double-groove roller tube, two simultaneously fabrics can be mounted. This system is also known as the Twin-Roll screen system.

A vertical screen system is powered by tube motors. Thanks to the compact installation dimensions of tube motors, it is particularly suitable for mounting in the roller tube. As a result, the required installation space in the greenhouse is limited. In some cases, tube motors are undesired, and are replaced by external drive motors that roll the roller tube. This motor must then be guided up-and-down along with the screen movement.