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The future of greenhouse climate management

A specialist in developing, producing, and marketing growing media, fertilisers, soil improvement materials, and composting products, Biolan has recently developed an innovative greenhouse management system that offers some major benefits for a relatively small investment and low operating costs.

Biolan has developed the system by combining a new method for cooling greenhouses with existing technology to create an energy-efficient concept for closed greenhouses that really delivers in terms of a lower energy requirement, enriched CO2 levels for better plant growth, and better pest and disease control.

Known as Novarbo™, the patentpending system sprays a controlled curtain of water droplets along the roof of a greenhouse to conduct moisture and heat away. The water is collected at floor level and sent to a reservoir outside the building, where it is filtered and allowed to cool before being recycled back into the greenhouse.

Initial versions of the system were tested with cucumbers, and resulted in a 30% increase in overall yield and a 40% increase in the yield of premium-quality cucumbers compared to a conventional greenhouse system using ventilation and fogging to control temperature and humidity.

Suitable for a range of climates

By keeping CO2 inside rather than losing it when the excess heat from supplementary lighting has to be vented, the Novarbo™ system helps growers get more out of their greenhouses.
A closed greenhouse environment offers many advantages, and the concept has been the subject of extensive R&D in the horticultural industry in recent years. A closed environment enables all the factors affecting growth to be optimised, particularly CO2 levels during periods of high light conditions, plant protection, and minimising the loss of heat that takes place when ventilating excess humidity under artificial lightning in a cold climate.

The Novarbo™ system absorbs the excess heat and moisture generated by the sun and artificial lighting without using forced ventilation by binding it to the water in the system’s curtain of water droplets. The curtain condenses the latent heat and acts like an open-air heat exchanger. By enabling a higher level of CO2 to be used and coupling this with additional lighting and advanced temperature control, the Novarbo™ system also opens up new opportunities for timing the growth of different crops.

Trials lasting two years in a commercial greenhouse have shown that the system offers a coefficient of performance (CO P) of 60-200, which is very high compared to that of normal heat pump systems, which typically have a CO P of 3-8. Trials also confirmed significantly higher crop yields, up 25-41% with cucumbers, 25% with cut roses, and 10% with tomatoes.

It’s all in the droplets

  • The curtain of droplets provided by the nozzle
    units in the Novarbo™ system absorbs heat and
    moisture. One curtain every 10 metres across a
    greenhouse is sufficient
  • A droplet separator unit at floor level collects
    the water, separating it from the stream of air
    generated by the curtain
  • Water is returned to a cooling pool
    (100-400 m3/1,000 m2)
  • A filtration unit keeps water in the pool
    clean. Chemical disinfection can be used if
    needed
  • Overall system control is provided by a
    greenhouse’s normal automation system.
> Teppo Rantanen
(Published in HighTech Finland 2010)