The "Kas als Energiebron" (Glasshouse as an Energy Source) programme is helping to meet the Netherlands' ambitious sustainability targets through a combination of use reduction, renewable energy generation and more efficient use of fossil fuels.
This was the verdict from energy policy adviser Aat Dijkshoorn at a recent meeting of UK glasshouse growers hosted by the Horticultural Development Company (HDC) and GrowSave.
The Dutch government intends that new glasshouses should be climate-neutral from 2020 and existing ones should cut energy use by 50 per cent on the 2010 figure.
"Already over 50 per cent of Dutch glasshouse production is heated by combined heat and power," said Dijkshoorn. Geothermal power "is a hot topic in the Netherlands with 10 glasshouse sites already using it - that would not have happened without this programme".
Meanwhile, a range of efficiency measures are being trialled at the GreenQ research glasshouse complex and with commercial growers under the "New Growing" (Het Nieuwe Telen, HNT) programme. These include drawing in outside air, circulating air from top to bottom within the glasshouse and extra energy screens - measures that have 50 per cent subsidies - as well as temperature integration, aquifers and heat pumps.
Consultant Paul Arkesteijn of screen manufacturer Svensson added that, while the company's single Revolux screens have been shown to save 11cu m of gas (108kWh) per square metre per year in tomatoes and 14cu m in cucumbers, a second such screen upped these figures to 22 and 24cu m respectively.
Grodan crop consultant Andy Lee added: "We see double screens eventually becoming standard."
Dijkshoorn explained that other technologies currently under investigation include double glazing - but he warned "we don't expect this to be any time soon" - as well as new dehumidifying technology and hybrid LEDs.
Meanwhile, more than 100 firms are part of study groups under the HNT programme. "They want to know what they can do now," he said. It is expected to continue despite the likely abolition of industry levy body and part-funder the Dutch Horticulture Production Board at the end of this year, a move that Dijkshoorn described as "ideologically driven".
Case closed - Glasshouse method dropped
Hailed a few years ago as the next big thing in sustainable glasshouse growing, so-called "closed glasshouses" have been quietly dropped by the Dutch horticulture industry, Aat Dijkshoorn told the meeting. "Some that were used for salad have been abandoned, though you can use them in a different way. Right now Lans Tomatoes has the only fully closed tomato glasshouse in use. But we'e learnt a lot from them."