Adaptive greenhouses, fitted with a cover that can be adapted to the outside climate on a monthly or even hourly basis for example, could reduce the costs of heating and dehumidification by 30 to 60 per cent. This is one of the conclusions drawn from the CAGIM, Climate Adaptive Greenhouses project: Inverse Modelling. Additionally, an adaptive greenhouse cover could increase production by 14 per cent, too.

These data were presented at the ‘Smart adaptive façades for greenhouses and commercial or industrial buildings’ symposium held at the Rotterdam Ahoy Stadium on 27 January. Researchers from various universities and knowledge centres and the greenhouse horticulture industry have been exploring the possibilities offered by dynamic and adaptive façades, as well as greenhouse covering and control systems, for some time. This research showed that this technology in theoretical calculations could lead to substantial energy savings from which greenhouse production will also benefit.

Non-stop adjustments

In an adaptive greenhouse, the individual properties of a greenhouse – such as the glass, the insulation, the air supply – are continually adapted to guarantee maximum plant growth and a minimal use of energy. The researchers based their research on a situation that is unhindered by the availability of the necessary technology and materials. The success of the project therefore depended on the availability of all the necessary technology. As this is not yet possible in practice, we will still have to wait some time before fully adaptive greenhouses can be built.

Energy-neutral greenhouse

During the symposium Laure Itard of The Hague University of Applied Sciences and Delft University of Technology demonstrated that a fully adaptive situation for greenhouse horticulture will be possible in the near future. In other words, the energy-neutral greenhouse is just around the corner. A number of technological feats, materials and breakthroughs are responsible for this:

  • Intelligent greenhouse covering material;
  • Methods to eliminate excess heat, without any concessions to light;
  • Isolating the properties of building materials;
  • Transparent insulation and adaptive coatings;
  • Climate façades;
  • Electricity generation through greenhouses.

Other crucial elements are various types of screening systems and adaptive control strategies.

Gert Jan Swinkels of Wageningen University Research Centre presented various trials and pilots that were carried out with innovative greenhouses. Before he started, he emphasised the important of sunlight. ‘You can’t beat sunlight in terms of efficiency. Growing a single kilo of tomatoes in a modern greenhouse takes 0.7 m3 of natural gas. However, if you are using the most efficient type of state-of-the-art LED lighting, you will need 2.7 tot 3.5 m3 of natural gas to grow the same kilo of tomatoes. And 1% extra light still translates into 1% extra yield.’

High-tech greenhouses

The high-tech greenhouses that provided a large portion of the input for the adaptive greenhouses of the future are, in random order:

  • The DaglichtKas; the daylight greenhouse that intercepts direct sunlight and uses this to generate heat while allowing diffuse light to pass through for the crop;
  • The ELKAS; the electricity-producing greenhouse that generates electricity from any sunlight not needed by the crop;
  • The VenLowEnergy Kas; a greenhouse that uses state-of-the-art systems, requiring only 0.2 m3 natural gas per kilo of tomatoes;
  • The 2SaveEnergy Kas; a greenhouse that uses conventional glass covered with specific types of foil, requiring only 0.23 m3 natural gas per kilo of tomatoes;
  • The Winterlight Kas; a greenhouse that allows 10% more light to enter the greenhouse in winter, thus increasing yield by 20% in comparison to a state-of-the-art reference greenhouse.

Download the entire Climate Adaptive Greenhouses research report: Inverse Modelling or visit this website for more information.

Text: Rob van Mil. Photo: Mario Bentvelsen.