Plants no longer exclusively grow in a particular region and during a specific season but in greenhouses all over the world. PLEXIGLAS® contributes to a sustainable production of vegetables and flowers.
Strawberries in winter and fresh flowers are only available all year around because millions of plants can grow in huge greenhouses simultaneously. Such commercial professional greenhouses are high-performance facilities, whose operators place specific requirements on the materials used. For example, the materials need to let in as much light as possible as it enables fast growth and intensive colors. At the same time, energy-efficient production is gaining ever more importance.
10 reasons for PLEXIGLAS® in greenhouses
High light and UV radiation for the best growth results
After all, the prices for gas and other energy sources have increased significantly in the past decades and the global climate objectives demand the reduction of CO2 emissions. Moreover, sustainability also plays an ever-greater role for consumers. “Energy is a crucial factor for sustainability in commercial fruit, vegetable and flower cultivation,” says Bernd Petri, responsible for roofing products made of PLEXIGLAS® at Röhm. For plants to grow all year round at stable temperatures, cooling is required in summer and heating in the winter. “By reducing their energy consumption for heating and air conditioning, greenhouse operators make a positive contribution to climate protection and can save money at the same time,” explains Petri.
Improving insulation in greenhouses
An important starting point for saving energy in commercial plant cultivation are well-insulated greenhouses. They require less heating in winter and less cooling in summer. The multi-skin sheets made from PLEXIGLAS®, the brand acrylic glass from Röhm, are very well suited for this task. They are made from two sheets, whereby the upper sheet rests on multiple connection bars which in turn rest on the lower sheet. The resulting air cavities act as an insulating layer, as the static air in the cavities is a poor heat conductor compared to solid material. “PLEXIGLAS® multi-skin sheets provide much better insulation than single glazing,” says Petri.
Thanks to their insulation, PLEXIGLAS® multi-skin sheets reduce the energy required in greenhouses compared to conventional glazing. Furthermore, greenhouses made from PLEXIGLAS® provide the plants with the right combination of sunlight and UV rays.
A material’s U-value indicates the thermal transmission coefficients. The lower the value, the less energy passes through the material. Materials with a lower U-value are thus better insulated than those with a higher U-value.
With a 16-millimeter-thick PLEXIGLAS® multi-skin sheet, the heating energy consumption can be reduced by around 40 percent compared to conventional, single-glazed greenhouses. Maximum insulation is achieved by the 32-millimeter-thick multi-skin sheet PLEXIGLAS® Resist NO DROP. PLEXIGLAS® Heatstop SDP, on the other hand, can reflect infrared rays and reduce the heat generated in greenhouses in very hot regions. “Through this energy conservation, the investment is amortized within a few years,” says Petri.
High light transmittance
Equally as crucial in commercial plant cultivation is that, despite this excellent insulation, the light transmittance is not affected – unlike with other materials. “Glazing for greenhouse construction should allow at least 85 to 90 percent of the light to enter the greenhouse,” explains Petri. “Our multi-skin sheets combine good insulation with a high light transmittance of up to 91 percent,” says Petri. “These kinds of values can usually only be achieved by single-layer materials.” 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.
A greenhouse for extreme conditions
For good plant growth, greenhouses require a material with high light transmittance – or, in other words: one percent more light means one percent more growth. PLEXIGLAS® multi-skin sheets let in enough sunlight for tomatoes, cucumbers and other crops, even in inhospitable regions such as the Antarctic.
Around 40 years ago, Dutch operators became the first pioneers in greenhouses made of PLEXIGLAS®. During the first big energy crisis, the brand acrylic glass became even more popular among plant cultivators – not only to save heating energy, but also because the material is more robust than glass. A factor that should not be underestimated in the stormy coastal regions of the Netherlands. In the USA, Japan and Scandinavia too, PLEXIGLAS® multi-skin sheets are well established in greenhouses as well as in zoos and botanical gardens. “The durability of our material also plays a big role here. After 30 years, there is still no sign of any yellowing, meaning it maintains its maximum light transmittance permanently,” explains Petri.
Different versions of PLEXIGLAS® multi-skin sheets are available for the various requirements worldwide. For example, the PLEXIGLAS® Resist SDP multi-skin sheets are particularly robust and thus even more impervious against hail. “Greenhouses made of PLEXIGLAS® create a climate in which vegetables can ripen and plants can thrive,” says Petri. “At the same time, the good insulation allows operators to save energy, which in turn reduces heating costs and protects the environment.”