S06 - Session O4 - Are smart glasses with switchable optical properties the future greenhouse covers for high value crops?

Authors: Nieves Garcia Victoria *, Silke Hemming, Cecilia Stanghellini, Esteban Baeza Romero

Electrochromic glasses (EC Glass) able to instantaneously switch light intensity were evaluated on their potential for production of high value ornamental crops, such as Anthurium sp ., assumed to benefit from constant relatively low sunlight levels. Growers use shading screens or temporary coatings on glass during summer, which either react slowly or not at all to changing outside light conditions. EC Glass allow light intensity control in real time and therefore more constant light conditions. Two experiments were conducted with pot anthurium, within the public-private collaboration project Smart Materials. Research questions were: Is EC glass able to control light intensity on a constant level with changing sunlight conditions? Does it improve crop growth and quality? In the first experiment, EC Glass was compared with other shading treatments achieving comparable light sums but slower control or no shading. In the second, the EC Glass was compared exclusively with coated glass, both aimed at maintaining slightly higher light sums than in the first experiment. The light levels were well controlled under EC Glass. In the first experiment there was a trend to shorter plants and smaller leaves & flowers compared to reference plants grown in a "normal" greenhouse due to overheating of the glass panes on dark state and consequent overheating of ambient air during hot days. In the second experiment plants under EC glass received higher light sum by more constant light, less peaks on sunny days and more light on clouded days. However, this did not translate in faster growth, more flowers or better plant uality. The achieved light advantage by the EC glass was counteracted by high leaf temperatures that lead to stomata closure and lower photosynthesis efficiency during sunny periods. More research is required to evaluate the potential of smart glasses as greenhouse covers for high value crops.