Voen tunnel 2012

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Use of tunnel technology is becoming widespread around the world as part of farmer risk mitigation strategies. Voen Covering systems of Germany have a plastic covering system that retro fit existing propriety tunnels with vented plastic cover which eliminate one of the main problem when using exiating plactic covers -- it get too hot.

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Voen tunnel 2012

  1. 1. Tunnel TechnologyHow advanced is it?
  2. 2. Why use this Tunnel ?– Environmental protection, wind bird rain– Cost affective– Crop timing– Assurance of supply– Protection against rain– Protection against hail– Protection against birds– Protection against sun– Protection against frost– Has to provide an improved microclimate– Has to by wind resistant– Has to be easy and quick to set up and take down– Has to be cost affective / economical– Reduce chemical inputs
  3. 3. World is not perfect and either are Tunnels• Issues – Temperature and humidity control – Wind – continual maintenance – Labor intensive – Higher management input, pest and irrigation
  4. 4. No 1 enemy
  5. 5. Wind• 20 may 2011• “Scottish soft fruit growers – Hit by storm-Catastrophe • 1500 acres of tunnel lost • $42m damage • Yield down 25% • Source BBC news
  6. 6. Ventilation PrincipalsNatural VentilationDriving Forces –Thermal BuoyancyWindMechanicalVentilationDriving Force–Fans
  7. 7. The VOEN covers overlapping flaps hailnet base double stitched and glued
  8. 8. The idea: Permanent ventilation Regulation of temperature Plant health Characteristic growth Stable acid values Stable firmness of fruits Fruits with good size and best quality
  9. 9. The idea:Permanent ventilation
  10. 10. Temperature comparison Tunnel – Venting tunnelIn average 2-4°C less temperature in a tunnel with VOEN ventilation. Already slight air movements provide ventilation of the VOEN film.The difference goes up to 9°C.
  11. 11. Realised projects: Tomatoes in Czech Republic Prevention of bacteriosis Regulation of peaks intemperature
  12. 12. Realised projects: Provence / France Venting covers on raspberries Summer temperatures about 40°CRegulation of peaks in temperature
  13. 13. Realised projects: Southern Germany Venting covers on apricots Minimum of humidityPrevention of diseases and cracked fruits
  14. 14. Realised projects: Southern Germany
  15. 15. Technical information Single Bay Tunnels Venting surface from the bottom up to an angle of minimum 40°Steep hoops for more venting surface
  16. 16. Technical information Multi Bay Tunnels Small venting area with flat angles
  17. 17. Technical information Multi Bay Tunnels Good venting area with steep angles
  18. 18. Typical Tunnel construction
  19. 19. Risk mitigation• Tunnel design and management is moving at an incremental rate• Use of Tunnels should be seen as part of your farms risk mitigation strategy.• Sufficient evidence exist to suggest your highest risks are wind and Climate control• Therefore you need to consider strategies around wind and climate.
  20. 20. Options for consideration and thoughtsWind.Consider the shape and strength of you hoopsHave you sufficient anchorageIs the location shelted or in a wind funnel?In long tunnels- should it be anchored and braced ever 50 m on windy sitesHow can the wind escape?
  21. 21. Options for consideration and thoughtsClimate• How am I going to ventilate the tunnel• Drainage- where is the Roof water going?• Do I need to irrigate more.?• Do I need to monitor tunnel temperate?• Will tunnels increase or decrease pest and disease management ?
  22. 22. Self-ventilating Plastic for tunnelsAdvantages• Guaranteed crop• Reduced losses• Reduce labor cost for cooling• Safety lever for spike in temperature• Even temp. – rise and fall• Can handle strong winds- blows through• Higher shade• Reduce plastic replace- high UV stabilization- 5-7years
  23. 23. Self-ventilating Plastic for tunnelsDisadvantages• Increase cost• Installation time could be slightly slower
  24. 24. Thanks for your attention

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