Perfect light conditions are essential for optimum plant growth. Greenhouse yields depend on whether these conditions can be achieved during all harvesting cycles whilst keeping costs low.
ETFE greenhouses offer a high performant alternative to conventional constructions made of glass or durable composite materials. In addition to the functional features of ETFE films, NOWOGREEN® offers further properties, that help maximize the light inlet of greenhouses.
How does it all work? Let us guide you through the different harvesting cycles in an ETFE greenhouse by the example of strawberries:
Cycle 1 – January to April
In winter and early spring, the intensity of sunlight is still comparatively low. The objective is to make the best possible use of them. The clear variant of NOWOGREEN® offers 94 % light transmission (92 % for the diffuse type). In combination with the self-cleaning properties (lotus effect) of ETFE films, unimpaired UV transmission is guaranteed. Thanks to its high surface tension, nothing can adhere to the film. Water and dirt simply roll off, which keeps the film clean.
Thanks to innovative coating, similar effects are also guaranteed on the inside of the greenhouse. As a result of temperature fluctuations between day and night, condensation can form on the inside of the greenhouse. Standing drops of water on the film have a lens-like effect and concentrate the sun rays, resulting in burn marks on the harvest products and overall reduced light inlet. Recent studies reveal that condensate on the glass can lead to 7 % light loss. When light levels are low, up to 20 % light loss must be expected. As a result, the plants are supplied with less light, which inhibits plant growth. (Source: Study GTB -1025 by Wageningen University UR).
The solution: NOWOGREEN® features a special anti-drop coating that prevents the formation of droplets. The hydrophilic coating on the inside of the film ensures that the rising condensate forms a laminary film of water, which drains off the surface in a controlled manner. This prevents the film from steaming up and guarantees excellent UV transmission.
The transparent NOWOGREEN® film offers an SHGC-Value (Solar Heat-Gain Coefficient) of 94 % (diffuse variant: 92 %). That means the IR thermal radiation heats the greenhouse and the energy demand and respective costs for heating the greenhouse are reduced.
Cycle 2 – May to July
During this time the sun unfolds its maximum power. Too much power actually, when the aim is to ensure ideal conditions for plant growth. Long lasting high UV radiation heats up the air inside the greenhouse significantly. 90 % of installed greenhouses are therefore lacquered with chalk paints to minimize the UV radiation and to protect the crops. At the end of this phase, the paint needs to be washed off again in order to prepare for Cycle 3.
Lacquering and the later wash-off of the chalk paint generate additional costs for materials, personnel and equipment. An overview:
- € 2.000/Ha/Saison for lacquer and solvent
- Vast amounts of water to wash off the paint without leaving any residue
- Appropriate equipment
- Additional staff costs
Due to the high surface tension of the ETFE film the chalk coating for shading does not adhere to the film. A long-term solution available on the market are shading screens, which can also be controlled electronically and deployed automatically to regulate the shading individually. Shading systems such as these are not only efficient, but also more sustainable as vast amounts of water are saved.
Cycle 3 – August to December
Autumn comes and days are becoming shorter again. Every ray of light that can be obtained without additional artificial lighting is valuable. In this cycle, the self-cleaning properties are again beneficial as rainwater and dirt simply run off, while the inner anti-drop coating supports the optimum light transmission.
One film that masters the lighting challenges in all harvesting cycles. Due to their numerous advantageous properties, ETFE films are becoming increasingly established in greenhouse construction. In addition to the described properties, the films also impress with decade-long durability and light weight, allowing costs for maintenance and construction material to be lowered. Thanks to its high elongation at break, the film can also withstand hail (class 3) without shattering. NOWOGREEN® – The superior way of greenhouse covering.
About Hueck Folien
The film coating specialist based in Baumgartenberg/Austria has more than 20 years of experience in ETFE film coating in the architectural sector and gives the films a special look and functionality through different coating solutions, printing patterns and colour options: from innovative shading to maximum weather resistance and hydrophilic properties.
NOWOGREEN® is a patented product developed in cooperation between Nowofol® and Hueck Folien. The entire supply chain is based in Europe.
Visit our website for detailed information and demonstrational videos: https://www.hueck-folien.com/en/design/nowogreen
