When making plans for a new greenhouse, one of the first things to determine is the principle design and its cover material. Often growers are weighing the odds between two materials; glass or polyethylene. But did you know that there is also a third material that combines the best of both worlds?
Ethylene Tetrafluoroethylene, better known as EFTE, is a fluorine based material that at first sight looks like a standard polyethylene greenhouse film. But according to Luigi Pezzon of Italian thermoplastic film manufacturer PATI, the physical and chemical characteristics of the two films are different, and EFTE can be better compared with glass than with polyethylene.
A major benefit of EFTE is the high light transmittance of the material, also in the UV bands. "EFTE is very clear and has a high light transmission of 93%, which is higher than standard glass or polyethylene film", said Pezzon.
It is known that more light usually means more production, so why does not every greenhouse has EFTE on top of their greenhouse? "Well, that has to do with the cost of the material", explained Pezzon. "The chemical compound and manufacturing process makes EFTE a very good material but also and expensive material. The price is more in the region of glass than in the price region of poly."
Yet, plenty of growers prefer EFTE above polyethylene due to its excellent light characteristics. But there is more too it. Pezzon: "Despite the fact that it is more expensive, it is more durable and has a very good life span that can last for 15 to 20 years. It is no longer needed to replace the film every few years, and due to the special chemical composition the high light transmission does not deteriorate."
On top of this, the film has a built in dirt resistance: The low surface tension of the EFTE film makes for a self-cleaning material that does not hold any dust or any other pollution. A rain shower is enough to clean the greenhouse and it is not required to clean the roof with a roofwasher.
By making a one time investment in EFTE, a grower will save costs as he does no longer need to wash or replace the film anymore. EFTE is also known for its excellent heat retention characteristics; it keeps the heat inside much better, which is especially interesting for cold climate horticulture."
For these reasons, PATI has delivered many EFTE material to professional growers in countries in Northern Europe like Holland and the UK. These growers are motivated by the high light transmission and energy saving characteristics of the film.
Yet, Pezzon also sees a future for the film in regions with many sun radiation, that destroys standard film. "For growers that need to replace their film every two year due to the intensive sun radiation and heat it becomes very interesting to consider EFTE too. That is why we ship many EFTE to growers in the Middle East and countries with tropical climates."
Pezzon also explained that EFTE is often installed in botanical gardens and architectural designs, such as the Beijing Olympic Swimming Pool. In these situations EFTE is also preferred above glass due to the weight and flexibility.
"This is also an interesting aspect for greenhouse growers, as they can save on the costs of their structures when installing a lighter EFTE film instead of much heavier glass."
The Olympic swimming pool covered with EFTE.