This document discusses tunnel technology for crop protection and cultivation. It provides advantages such as environmental protection, cost effectiveness, crop timing assurance, and protection from weather elements. However, it also notes issues like temperature and humidity control, wind resistance, maintenance needs, and pest and irrigation management. The main challenges are wind damage and climate control. It then discusses ventilation principles and realized projects using venting tunnels for tomatoes, berries, and stone fruits. Technical specifications for venting area and angles in single and multi-bay tunnels are also covered. Finally, it considers options for wind protection and climate control, as well as the advantages and disadvantages of self-ventilating plastics for tunnels.

2. Tunnel Technology
How advanced is it?

3. 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

4. World is not perfect and
either are Tunnels
• Issues
– Temperature and humidity control
– Wind
– continual maintenance
– Labor intensive
– Higher management input, pest and irrigation

5. No 1 enemy

6. 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

7. Ventilation
Principals
Natural Ventilation
Driving Forces –Thermal Buoyancy
Wind
Mechanical
Ventilation
Driving Force–Fans

10. The VOEN covers
overlapping flaps
hailnet base
double stitched and glued

11. 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

12. The idea:
Permanent ventilation

13. 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.

14. Realised projects:
Tomatoes in Czech Republic
 Prevention of bacteriosis
 Regulation of peaks in
temperature

15. Realised projects: Provence / France
 Venting covers on raspberries
 Summer temperatures about 40°C
Regulation of peaks in temperature

16. Realised projects: Southern Germany
 Venting covers on apricots
 Minimum of humidity
Prevention of diseases and
cracked fruits

17. Realised projects: Southern Germany

18. Technical information
 Single Bay Tunnels
 Venting surface from the
bottom up to an angle of
minimum 40°
Steep hoops for more venting
surface

19. Technical information
 Multi Bay Tunnels
 Small venting area with flat angles

20. Technical information
 Multi Bay Tunnels
 Good venting area with steep angles

21. Typical Tunnel construction

24. 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.

25. Options for consideration and
thoughts
Wind.
Consider the shape and strength of you
hoops
Have you sufficient anchorage
Is the location shelted or in a wind funnel?
In long tunnels- should it be anchored and
braced ever 50 m on windy sites
How can the wind escape?

26. Options for consideration and
thoughts
Climate
• 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 ?

27. Self-ventilating Plastic for
tunnels
Advantages
• 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

28. Self-ventilating Plastic for
tunnels
Disadvantages
• Increase cost
• Installation time could be slightly slower

31. Thanks for your attention