Diffuse glass can potentially contribute to the objective of a profitable sustainable greenhouse horticulture, due to the improved growing conditions (production and quality) without energetic consequences. In research experiments it has been repeatedly proven that diffuse glass leads to a higher yield. However, adoption of diffuse covers in practice has been met by some skepticism. The main reason is that in practice (contrary to experiments) the components light and diffusivity are inextricably linked. That was the reason for this research, in particular to unravel light transmission and diffusivity in commercial practice. For this project, the data from 5 growers were used, who have both a greenhouse with a diffuse greenhouse cover and a greenhouse with a clear greenhouse cover, with crops of cucumber, tomato and cherry tomato. Climate data, light level at crop height and yield data were analyzed to answer two questions 1. “Does diffuse glass result in a higher yield in practice?” And 2. “Does the energy use under diffuse glass differ from the energy use under clear glass?”. To correct for other factors (such as planting date), the “radiation use efficiency” has been determined for all crops, that is: how many kilos are harvested per unit of available solar radiation. On average for all crops, the RUE in the diffuse greenhouses was 8% higher compared to the clear greenhouses. After correction for all other factors, there is clearly no difference in energy consumption between the diffuse and the clear greenhouse. Therefore, the energy efficiency in the diffuse greenhouses is higher compared to the clear greenhouses.
|Name||Rapport / Stichting Wageningen Research, Wageningen Plant Research, Business unit Glastuinbouw|