revive producers with a simple energy-efficient glass

Agculture announces the launch of Geysir, the first energy-efficient monoglazing with high hemispherical light transmission. “With this product, we are continuing our vision of empowering growers to grow healthier crops and increase yields while reducing their use of carbon-based energy resources,” the Agculture team says.

European producers have suffered greatly from the unprecedented increases in gas prices last year. “As experts in the field will attest, anyway what can be found to save on gas consumption really makes a difference these days. But even before these recent challenges, the horticulture industry had already embraced the movement towards more sustainable solutions to reduce the amount of CO2 emitted for each kilogram of crop produced,” explains the Agculture team. “Geysir was designed in part to address these global concerns.”

Geysir is a clear float glass treated with a low-emissivity (low-E) pyrolytic coating applied immediately after float glass production. “As a result, this in-line coating is seamlessly integrated with the glass surface, providing exceptional durability. The glass is then vacuum coated with two durable AR coatings to increase PAR and hemispherical light transmission to levels comparable to products horticultural glass coatings. E and AR coatings are considered Class A coatings by European standards, attesting to their long-lasting performance.”

Immediate energy savings
The durable low-e coating applied to the exterior surface of Geysir reflects far-infrared heat back into the greenhouse, ensuring the glass acts as a fully transparent single-layer energy screen. The result: up to 22.2% less gas consumption per year based on the latest WUR research funded by the Dutch greenhouse horticulture organization “Kas als Energiebron”*. Thanks to this energy-saving coating, the glass allows maximum light into the greenhouse, especially in winter when natural light is scarce and when the use of additional mechanical energy-saving screens would reduce the amount of natural light entering the greenhouse, thus requiring a greater use of lamps with assimilation and therefore increasing the consumption of electricity. In other words, with Geysir, growers can use fewer screening hours and increase the amount of natural light in their greenhouses during the time of year when natural light is limited.

Crop and leaf temperature control means healthier crops
The amount of energy lost by crops and leaves depends on sky conditions. When the sky is clear and the sun is shining, the sky temperature is low. The crops sense this and begin to lose energy, which leads to a drop in leaf temperature and an increased risk of condensation forming on the leaves. The result is a higher likelihood of bacteria and disease. Low-E Geysir glass reflects radiative heat loss from crops when the sky is cold but clear. On the other hand, a cloudy sky means that the temperature of the sky is high and therefore the crops do not lose much energy since the clouds themselves act as a low-e coating. In this case, there is less need for low-e glass, and if it rains and the glass gets wet on the outside, then the low-e effect is reduced (at a time when it is not anyway not necessary).

Less condensation, higher relative humidity, indirect energy savings
Due to the position of the low-e coating on the outside of the greenhouse, any heat reflected from the coating passes through the glass twice, resulting in a higher glass temperature. This means less condensation on the inner surface of the glass and a subsequent increase in relative humidity (RH). Interestingly, the increase in relative humidity did not lead to more condensation on the leaves due to the fact that the temperature of the leaves also increased. Additionally, higher RH leads to more latent heat and more stable air temperature, giving the grower a better opportunity to more easily and efficiently control the climate inside the greenhouse. Higher RH also means heat pumps can consume less gas, providing secondary savings for producers. These are all the benefits of deploying Geysir.

WUR: first harvest under Geysir

No trapped heat in summer
One of the potential problems with low-e glass in the summer is that it retains heat. Why? Since solar radiation converts to far infrared after it is re-emitted inside the greenhouse, and the low-e coating reflects all far infrared radiation, it could cause heat to be trapped inside. In such cases, growers may need to ventilate their greenhouses more, which can lead to CO2 loss and subsequent reduction in crop yield. However, if Geysir is whitewashed, it will lose its low-E effect as long as the whitewash is on the glass. This is what most cultivators do in the summer, and as a result the whitewashed Geysir acts like normal glass and heat is no longer trapped. Of course, once the whitewash is removed, the glass regains its low-e functionality and is ready for the next cold season. The high durability of both coatings ensures consistent performance each time whitewash is applied and removed.

Ideal for cold climates
In cold climates like Northern Europe and America, the cold season is longer than the hot season, requiring greater energy consumption by greenhouses compared to other parts of the world. On the other hand, the market value of the crop is much higher in the cold season compared to the warm season, due to higher operating costs during winter in cold climates. This, added to current gas prices, is making life more difficult for producers. As mentioned above, Geysir can increase winter greenhouse yields while saving significant amounts of energy. WUR is currently conducting an experiment with Geysir in Bleiswijk (the Netherlands) to demonstrate all the above advantages of this glass. The experiment will end in December, but promising results have already been observed.

For more information:
Mohammad Shayesteh
[email protected]