FILM PLASTIC GREEN HOUSE-GLASS HOUSE- GREEN HOUSE WITH DOUBLE LAYER COVERING

1. FILM PLASTIC GREEN HOUSE-
GLASS HOUSE-
GREEN HOUSE WITH DOUBLE LAYER
COVERING

2. GLASS GREENHOUSE
• Glass as glazing materiel
• High light transmission
• Higher air infiltration
• High initial cost
• Low thermal resistance- high heating cost

3. • 3 type glasses
1. Annealed glass
• Cheapest glass
• very weak and prone to cracking
• Broke into sharp pieces

4. 2. Tempered glass
• Heat-treated glass
• Very clear
• six times stronger than
annealed glass
• Expensive than annealed type
• Broke into granular pieces

5. 3. Laminated glass
• Two or more sheets of glass bonded using
ethylene-vinyl acetate (EVA) or polyvinyl butyral
(PVB)
• Do not break
• Block 99% UV radiation
• Resistant to high load
• Highly expensive

7. Single Pane Glass
• Low energy efficiency
• High heating cost
• Glass 3mm -Light transmission - 95%
- R-Value- 0.96

8. Double Pane Glass
• Energy efficient
• Low heating cost
• “Low-E” reflective coating
on the inner pane of
glass- insulator
• Double Glass 16mm- R Value -2.1
-light transmission -90%
• “Low-E” glass - R Value- 3.45
-light transmission- 70%

9. Designs for glasshouse
• Lean-to type
• Even span type
• Ridges and furrow type
-Less working cost
-Energy efficient

10. Ridges and furrow type greenhouse Even span greenhouse

11. Sash bar

12. FILM PLASTIC GREEN HOUSE
• Flexible plastic films- polyethylene,
polyester, polyvinyl chloride, polyvinyl
fluoride
• Polyethylene- since 1930s
• Most common type in India

13. Advantages
• Easier for covering- less time, less labour
• Low initial cost
• Cost of heating-40% lower than single layer
glass and FRP greenhouse
• Low cost of management

14. Polyethylene
• Most popular
• Thickness -200 micron
• Transmittance- 88-89%
• Susceptible to UV light-
-reduce light transmission
-become brittle
• polyethylene - 1-2 year

15. Cont…
• UV stabilized polyethylene -3-4 year
• Condensation of vapour on film
• Thermal resistance incorporated by IR
blocking chemicals

16. Polyvinyl chloride
• 8 mil - 4 year
• 12 mil – 5 year
• Transmittance-86%
• Vinyl film-static charge –attract dust-reduce
light transmittance
• Costlier than polyethylene

17. Polyester
• Higher life
• 5 mil on roof – 4 year
• 3 mil on wall – 7 year
• High light transmittance- same as glass
• Free from static electricity
• Heat retention curtains- capacity to block
radiant energy

18. Polyvinyl fluoride(PVF)
• Life- 10 year or more
• Light transmission- 4 mil- 92%
• 4 mil PVF- tensile strength-4 times of 6 mil
polyethylene

19. • Film plastic greenhouse designs are mainly
of two styles
1. Quonset-style greenhouse
2. Gutter-connected green house

20. Quonset-style greenhouse
• Less expensive
• Trusses- 0.75 inch pipe for 20 feet wide
greenhouse
-1 inch- 30 foot wide greenhouse
• Trusses - 30-36 inches apart
• Width of covering material -32 feet for 20
feet wide greenhouse
-40-42 feet for 30 feet greenhouse

21. Cont…
• Wooden frame- film is nailed to frame
• Metal frame-metal channel lock screwed to
frame –film tightened in it using wiggle wire

23. Gutter-connected greenhouse
• Gutter -12-40 foot apart
• Columns –in each or alternate gutter
-11 m row spacing
• Minimum exposed surface area-low heating
cost
• For 17 foot wide bay- 20 foot wide film

25. Greenhouse with double layer
covering
• Two layer film –dead space, in between
• Supporting upper layer-plastic strips, wood
strips ,metal channel lock
• 2 layer-outer layer 6 mil, inner layer 4 mil
• Squirrel cage fan- to inflate the space
between two layer (49-68 Pa)

26. Squirrel cage fan
metal channel lock

27. Advantages
• High energy efficient
• Improved insulation properties
• Light transmission can be controlled