Greenhouses made from PLEXIGLAS®: High energy efficiency, lower costs
Plants no longer exclusively grow in a particular region and during a specific season, but increasingly in greenhouses all over the world. PLEXIGLAS® multi-skin sheets contribute to sustainable production thanks to their excellent thermal insulation.
Greenhouses protect plants from the cold, too much rain and even hail. They allow fruit and vegetables to be cultivated efficiently – even in regions where the field conditions make it impossible to produce food all year round. This includes northern Europe, where gigantic greenhouses are in operation, as well as regions around the world plagued by drought. In these regions, scientists are using current research projects to test how greenhouses can extend the harvesting seasons.
One prerequisite for the sustainable production of fruit and vegetables is greenhouses that minimize the consumption of resources. Alongside water, energy is the main issue in commercial fruit, vegetable and flower cultivation.
High energy efficiency, lower costs
Cooling in summer and heating in winter: energy is a considerable cost factor for greenhouse operators. In Germany, operators already spend up to 10 percent or more of their turnover to heat their greenhouses, and increasing energy costs will drive this share higher.
Thermal insulation in greenhouses is the best way to save energy in commercial plant cultivation: The greenhouses then require less heating in winter and less cooling in summer. Good insulation is decisive for innovative greenhouses that convert sunlight to geothermal heat, thereby saving energy for the winter. The multi-skin sheets made from PLEXIGLAS®, the brand acrylic glass from Evonik, are very well suited for this task. The insulating properties of the multi-skin sheets help reduce the energy required in greenhouses when compared to conventional glazing.
What are PLEXIGLAS® multi-skin sheets?
Multi-skin sheets, often also referred to as twin-wall sheets, double-wall skin sheets, double-skin sheets or multilayer cross-braced plates, are hollow profiles. They consist of two parallel outer plates (braces) as well as, if needed, additional inner braces running parallel to the outer braces. The braces are connected to one another via crosspieces.
The resulting air cavities are characteristic for multi-skin sheets. The special construction of PLEXIGLAS® multi-skin sheets (see graphic) allows a high load capacity with relatively little sheet weight; it also allows a good to very good thermal insulation, as the static air in the cavities is a poor heat conductor compared to solid material.
Comparison of glazings
Thanks to their thermal insulation, PLEXIGLAS® multi-skin sheets reduce the energy required in greenhouses compared to conventional glazing. This can be determined by the material’s thermal transmittance, the U-value. The lower the U-value, the less energy passes through the material. Materials with a lower U-value insulate better than those with a higher U-value. Depending on the ancillary conditions, PLEXIGLAS® multi-skin sheets (U-value e.g. 2.5 W/m²K) can lead to over 50 percent energy savings in greenhouses compared to single glazing (U-value 5.8 W/m²K).
Reduce energy consumption
There are a number of varieties of PLEXIGLAS® multi-skin sheets with different thermal insulation levels available for differing international requirements on greenhouses.
The thermal transmission coefficient of a 16-millimeter thick PLEXIGLAS® multi-skin sheet is 2.5 W/m²K. Maximum thermal insulation is achieved by a 32-millimeter thick PLEXIGLAS® Resist NO DROP multi-skin sheet with a U-value of 1.5 W/m²K.
PLEXIGLAS® Heatstop SDP, in contrast, is able to reflect infrared rays, thereby reducing the heat generated in greenhouses in very hot regions.
Equally as crucial in commercial plant cultivation is that, despite this excellent thermal insulation of PLEXIGLAS® multi-skin sheets, the transparency is not affected – unlike with other materials. PLEXIGLAS® multi-skin sheets allow up to 91 percent of the incoming light rays to pass through – meaning it makes almost no difference whether a plant grows outdoors or in a greenhouse.
And UV radiation, which is so important for plant quality, easily passes through the sheets. In fact, light utilization is above average even during inclement weather. Through a patented technology against condensation formation, the sun rays will not be inhibited by drops of water, which can otherwise form in the often-tropical climate of a greenhouse.
Durable and easy to clean
The transparency remains intact for a long time. We guarantee that PLEXIGLAS® multi-skin sheets will show virtually no sign of yellowing, even after 30 years of continuous use, and that sunlight will continue to reach the plants. Find out more on the PLEXIGLAS® durability here.
In addition, PLEXIGLAS® multi-skin sheets are robust and easy to clean. Dirt and grime take far longer to stick to the especially smooth and non-porous surface than on other materials. This minimizes cost and resource-intensive cleaning processes. Even after many years, greenhouses with PLEXIGLAS® multi-skin sheets look almost like they did on the very first day. An investment in PLEXIGLAS® is an investment in a sustainable future.