Since 2018, there has been a standard that scientifically measures the light properties of greenhouse screens — NEN 2675:2018. This standard helps accurately determine and compare both light transmission and Hortiscatter for different climate screens, giving growers a fair basis for comparison.
Light transmission beyond perpendicular measurement
Perpendicular light transmission alone does not fully reflect how much light reaches the crop, because most light — especially in winter — enters a greenhouse diffusely rather than directly. Light comes from all directions, so diffuse light transmission is the key measure growers should consider when evaluating greenhouse covers and climate screens.
Investing in extra light pays off
Transparent energy-saving climate screens have become widely popular because they can be used during the day to save energy and reduce crop radiation. A simple rule applies across seasons: the more light a screen allows through, the faster the crop grows. On average, 1 % more light results in about 0.8 % more growth, and even small increases matter in dim winter conditions.
Diffuse light transmission matters
A lot of attention goes into measuring the diffuse light transmission of greenhouse glass, but the same care should be given to climate screens. Svensson Climate Advisor Joris Vermonden encourages growers to always request diffuse light transmission data according to NEN 2675:2018 when purchasing screens, or have samples tested. The cost of such measurement is minimal compared with the potential light gain achieved over years of production.
Choosing the right screens
In many crops, using a double energy screen has become the norm. The Luxous 1147 FR screen from Svensson is a highly transparent choice, but more growers now opt for combinations such as Luxous 1147 H2no FR. The H2no version allows condensation droplets to spread into a film, which can translate to a 7–8 % light gain when condensation occurs. This is especially valuable during extended screen use in autumn, winter and spring.
Improved light quantity and quality
Evaluating screens should include both the quantity and quality of light they transmit. Diffuse light is distributed more evenly over all leaves and can penetrate deeper into the crop canopy. This allows more leaves to participate in photosynthesis. Research from Wageningen University shows that increasing Hortiscatter by 10 % under the same conditions can boost crop growth and production by 2–8 %, depending on the crop.
Sun protection and Hortiscatter
For screens designed primarily for energy savings, diffuse light transmission is the main focus. For screens designed for sun protection, Hortiscatter becomes particularly important. Screens like Harmony excel by converting intense direct sunlight into high-quality diffuse light, benefiting overall plant health and light use efficiency.
Contact
For more information, please contact climate advisor Joris Vermonden at joris.vermonden@ludvigsvensson.com or +31 6 21 17 84 58.
