Practical tests confirm higher production under AntiReflect
The first growers to use the new AntiReflect coating are seeing higher production as more light is entering their greenhouses. AntiReflect is being launched commercially this year.
After many years of development and testing, Mardenkro is this fall launching its revolutionary coating which reduces reflection off the greenhouse roof. This new product brings more than 3% more light into the greenhouse all year round. The coating can be applied to any existing glass greenhouse, thus putting antireflection within reach of every grower.
More light converted into more production
Prior to the launch, several nurseries tested the coating at their nurseries last winter and spring. These practical tests confirm the increase in production, model calculations by Wageningen University & Research (WUR) reveal.
Using the Intkam crop model, the WUR researchers measured how well vegetable and ornamental crops were able to convert the additional incoming light into production. The result in tomato (standard cultivation) and sweet pepper was an increase of around 3%, with more than 5% in cucumber (2 crops per year). Production in rose and gerbera was up by more than 2.5% and by more than 3% in chrysanthemum. The calculations in ornamental crops took account of the assimilation lighting used.
Effective in all seasons
A proportion of sunlight is lost due to reflection off a greenhouse roof with standard glass and therefore cannot be converted into production. This reflection can be prevented with AR glass, but that is only an option in a new build. For existing glass greenhouses, AntiReflect works just as well – in fact, the coating scores even better in some respects. It is dirt-repellent, so less dirt adheres to the coated greenhouse roof than to standard glass. This feature can boost light gain in the greenhouse.
In the Light Lab at WUR, measurements and calculations were performed using the Raypro model to determine transmission at all angles of incidence. This is important because every additional percent of light counts in the darker months, when the sun shines in at a low angle for most of the day. According to this research, transmission is always between 3 and 4 percent higher than on uncoated glass over a large trajectory – from 0° to around 70°. The researchers concluded that the light gain is constant in all months. Besides PAR light, transmission of infrared light also increases, albeit to a lesser extent.
Coatings can be combined
AntiReflect can be left on the greenhouse roof all year round and lasts for at least a year. Other coatings such as ReduFuse and ReduHeat can be applied on top with no performance loss. When these coatings are removed at the end of the season, the AR function of the coating underneath remains intact.
Careful application is key
The amount of transmission depends mainly on the thickness of the coating. So Mardenkro has liaised with contractors to produce work instructions for applying a very even layer on a clean greenhouse roof. This can only be done mechanically. Some of these companies were involved in the trial phase and are fully aware of the level of care required, while others will have to carry out tests themselves to achieve the best result.
AntiReflect is only available as a ready-to-use formulation, so it is impossible to get the dose wrong.
To avoid damaging the coating, no fluoride-based cleaning products should be used on it. When removing a coating applied on top (such as ReduFuse or ReduHeat) with ReduClean, it is important to allow it to be washed off by rain and not to immediately remove it with a roof washer.
Exercising care at all times will ensure an effective coating that performs well and generates gains for the grower all year round.
