Around the turn of the year, by commission of Wageningen UR, The Bom Group converted the Sunergy® greenhouse at the Innovation and Demo Centre (IDC) in Bleiswijk from a closed greenhouse with cooling to a semi-closed one with roof vents.
During this, the existing roof glass was also replaced with the very translucent diffuse type supplied by Horti Glass International (type D75+AR). This is diffuse glass with a haze factor of approx 75% and is treated with ‘Sunarc’ anti-reflective etching. Measurement results from WUR give a direct light transmission for this diffuse glass of approx 99% and a hemispherical light transmission of approx 89%.
The existing screen systems were renovated, with the lower screen being provided with new XLS 10 Revolux fabric.
Monitor energy consumption
On 17 January, vine tomatoes of the race Komeett were planted in the greenhouse, simultaneously with the other IDC tomato greenhouse, a VenlowEnergy type. In the coming year, the cultivation and energy consumption of these two greenhouses will be compared together. The expectation is that the Sunergy® greenhouse will come out at an energy consumption below 20 m³/m² annually with a high production, given its abundant-light diffuse glass, while the VenlowEnergy® Greenhouse, with its roof of high-insulating glass could even come out under 12 m³/m² annually, though it has a somewhat higher cost price and will have slightly lower production. In the Sunergy® greenhouse, use is also made of a new dehumidification system (based on the Next Generation Semi-Closed Greenhouse), by means of which the air can be dried without loss of sensible or latent heat.
At the end of the year, we will know how the cultivation proceeds in these two greenhouse versions and how the light transmissions and energy consumptions compare together.
This research and the refurbishments are financed by the Ministry of Economic Affairs and the Product Board for Horticulture in the context of the research programme Greenhouse as Energy Source.
For more information:
WUR – IDC Bleiswijk
Feije de Zwart
Horti Glass International www.hortiglassinternational.com
Bom Group www.bomgroup.nl