A higher production due to diffuse glass?

Published on
July 1, 2019

Plants need light to grow. In greenhouse horticulture there is a golden rule: 1 percent more light ensures 1 percent more yield. But what happens if no glass is used in a greenhouse, but diffuse glass? Does that lead to even higher production, as is often thought, and to an increase in energy efficiency? The Greenhouse Horticulture Business Unit of Wageningen University & Research is investigating this at a large group of practice companies.

Diffused glass spreads the incoming sunlight. The light rays are then bent in different directions. The degree of spread is called 'haze'. Glass with a high haze factor ensures higher production, was the conclusion of a few experiments a few years ago: 10 percent more diffuse light means 1.5 percent more production.

But is that definition correct? And is less energy required when using diffuse glass? Many Dutch growers have their doubts and opt for 'normal' glass in the greenhouse construction for a new greenhouse.

Comparison between normal and diffuse glas

The WUR wants to know for sure once and for all what the effects of diffuse glass are on production and energy consumption. For this purpose, a study was started in the autumn of 2018 at a large group of growers of various crops, such as tomato, cucumber and strawberry. These growers - currently there are thirteen - use both normal and diffuse glass. This makes comparisons possible.

For these growers, WUR analyzes the climate data and production figures for recent years. In addition, light sensors are hung in greenhouses with and without diffuse glass. The properties of the glass used are checked with the relevant grower. This fall, WUR will present the first results of the research.

This research is funded by the Kas als Energiebron program.