By Kylie Gettleman
Ceres Greenhouse Solutions is now offering an exciting new glazing option for our greenhouses in the form of ETFE film. Widely used in Japan for decades but with little use in the United States, Ethelyne Tetrafluoroethelyne (ETFE) is a translucent polymer sheeting with great benefits for greenhouse production. At Ceres, we installed our first ETFE covering last year to retrofit a high tunnel for Warren Tech School in Colorado and we are now designing and engineering full-scale Ceres energy-efficient ETFE greenhouses.
Why Use ETFE?
ETFE film allows for more than 95% light transmission, including the UV spectrum. Even on low-light days, more light will be entering your greenhouse. Full-spectrum light, especially UV-A, plays an important role in plant health and nutrition. Your plants will grow faster, healthier, and taste better. In a natural UV environment, plants produce a higher number of protective compounds, like beta carotene, anthocyanin, and glycosides, that contribute to the color, flavor, and nutrition of many plant species. UV spectrum light also acts as gentle radiation, cutting down on molds, funguses, and certain plant diseases in your greenhouse. Our friends at Warren Tech have experienced a decrease in pest pressure, specifically slugs and aphids, since installing their ETFE film. We believe that this may have something to do with an increase in UV spectrum light in the greenhouse because researchers have found that higher levels of glycosides and other protective compounds deter pests in some plant species.
ETFE is lightweight and strong. Only 1/100th the weight of glass, ETFE allows for wider truss spacing and, therefore, less shading in your greenhouse. And yet, it is remarkably strong for how lightweight it is. ETFE can elongate up to 400% without breaking, making it a great option for locations that experience a lot of hail, high winds, or are prone to earthquakes. We have different thicknesses of ETFE we can offer (60 um – 300 um) based on site-specific weather challenges.
ETFE ages well. A typical polyethylene greenhouse will need to be re-sheeted every 3-5 years due to steadily lower light transmission levels. Data shows that ETFE will only lose 5% light transmission over 20 years. We have seen ETFE greenhouses in Japan continuing to perform well at over 30 years of age. ETFE is self-cleaning due to its nonstick surface, which means snow slides off faster than other glazing materials and it resists dust or pollen that contributes to lower light transmission levels.
ETFE can be installed in one or two layer configurations. The outer layer is thick (100-300 microns) to protect the greenhouse from the elements and is completely clear to allow up to 95% light transmission. The inner layer is able to be much thinner (60 microns). Both layers combined create a diffuse effect which eliminates shadows and scatters the light as it enters the greenhouse, allowing the light to penetrate the plant canopy more effectively. A bubble of air sits between the two layers of ETFE, which gives it an R-value of about 1.8 ft2·°F·h/BTU (US) or 0.32 m2·K/W (SI). ETFE film is available in clear or diffuse.
Diffuse ETFE Clear ETFE
As greenhouse designers, we are always on the hunt for new technology that will allow our clients to grow better, more efficiently, and more sustainably than before. Experimenting with new products is a huge part of what we do and we’re excited to be able to offer ETFE as an innovative solution to greenhouse growers that require full-spectrum, long-lasting, and highly durable glazing materials.
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