Green house technology

2. Introduction
• Green houses are relatively light structures to
maintain a favorable micro-climate desired by the
crop to be grown.
• Managing crop production inputs such as water,
seed, fertilizer etc. to increase yield, profit,
reduces wastes and become eco- friendly.
• The structure is supposed to withstand loads due
to its own weight, wind, snow, hanging baskets
and should allow maxim mum light transmission.

3. DESIGN CONSIDERATION
 Site Selection
 Orientation
 Size of green house
 Structural Design
 Height
 Availability of Electricity
 Source of Water
 Climatic factors
 Wind Effects

4. Site Selection

5. Some Extra Points…
• A greenhouse is designed to withstand local wind, snow and
crop loads for a specific cropping activity.
• In this way, the structure becomes location and crop specific.
• The building site should be as level as possible to reduce the
cost of grading, and the site should be well aerated and
should receive good solar radiation
• Provision of a drainage system is always possible.
• It is also advisable to select a site with a natural windbreak.
• To prevent shadows on the crop, trees located on the east,
south, or west sides should be at a distance of 2.5 times
their height.

6. Orientation

7. Structural Design
• The structural parts that can cast shadows in the
greenhouse should be minimized.
• A straight side wall and an arched roof is
possibly the most common shape for a
greenhouse.
• A hoop type greenhouse is suitable for low
growing crops, such as lettuce, or for nursery
stock which are housed throughout the winter
in greenhouses located in extremely cold region.

8. ARCH & HOOP TYPE

9. Size of green house
• Size of green house is should be selected on
availability of land.
• Depending on market access and experience of
greenhouse cultivation is suggested to start with a
naturally ventilated greenhouse having greenhouse
having minimum size of 100 m2.
• Experienced farmer may go for larger size of
greenhouse.

10. HEIGHT
• Ideal Height for naturally ventilated small
greenhouse (250m2) should be in range of 3.5 m
to 4.5 m and 5.5 to 6.5 m for larger green
house.
• For fan and pad cooling system should be
slightly less than naturally ventilated green
house but not more than 5.5 m.

11. Availability of Electricity
• Electric appliances such as motor, fan, light and
other measuring instruments need electric
power for uninterrupted operations.
• Ensure availability of electricity.

12. Source of water
• Availability of water in respect to quality and
round the year supply has to be ascertained
before finalization of the site.
• Pumping cost from wells and bore well should be
cheaper
• Micro irrigation system facilities should be
installed inside the green house.

13. Climatic factors
Sl.No
.
Climatic Factors Important Activities Desirable level in a
green house
1 Radiation/Light
Intensity
Photosynthesis,
Photoperiodsis, Photo
morphogenesis
25,000-50000 lux
2 Temperature Cell Division, Elongation,
Transpiration etc.
18-25oC (Air)
20-25oC (Soil)
3 Relative Humidity Quality of Plant 60%
4 CO2 Photosynthesis 350-1000 ppm
5 Air movement/Wind
/movement
Influence temp, RH & CO2
conc.
Inflow:Outflow-1:1

14. Wind effects
• If GH is naturally ventilated , advantage of
natural wind direction has to be taken to
maximum possible.
• The maximum dimension of GH should be
perpendicular to wind direction especially in
summer.
• For fan & Pan natural wind direction should be
same as the air blown by fan.

15. Various Components of Greenhouse / Poly-
house
• The main components of greenhouse like
structure, covering/glazing and temperature
control systems need proper design for healthy
growth of plants.
• Freestanding (single) or ridge and furrow (gutter
connected) greenhouses are two common styles
of commercial greenhouses.
• The freestanding style is often a Quonset, which
will accommodate many growing situations but
presents height.

16. Structural members of greenhouse
• Hoops
• Foundation
• Lateral supports
• Polygrip assembly: poly grip mechanism
will provide a firm grip of the ridge line pipe
and hoops at right angles without allowing for
slippage.
• End frame:

17. Foundation
• The foundation must resist overturning and vertical
pressure from structural loads and snow, and
should extend below the frost line.
• Concrete is the most appropriate material for
permanent structures.
• Specific recommendations are usually provided for
adequate durability of the foundation, experienced
builders, is highly recommended.

18. Contd…
• The foundation can be 60 cm x 60 cm x 60 cm or 30
cm diameter and one meter depth in PCC of 1:2:4 or
1:3:6 ratios.
• The vertical poles should also be covered to the
height of 60 cm by PCC with a thickness of 5 cm.
This avoids the rusting of the poles.
• *PCC stands for plain cement concrete. The mixture
of cement, fine aggregate (sand) and coarse
aggregate are generally called plain cement
concrete (PCC).

19. Structural Components

21. Structural Components

22. Side Wall
• It supports the trusses and bears the weight of the
greenhouse.
• Set in concrete footings
• Typically spaced 10 feet apart
Truss:
• Structural component that supports the weight of the
greenhouse roof.
• Consists of rafters, struts, and chords.

23. Purlin :
• Purlins run along the length of the
greenhouse.
• Keep the roof trusses aligned.
Ridge :
• Where the roofs come together at the top of
the greenhouse.
• Many greenhouses have a ridge vent(s).

25. Framing Materials
• Aluminum is the most economical material for
constructing the greenhouse frame.
• Steel is commonly used but must be painted or
galvanized to resist high moisture conditions within
the greenhouse.
• Wood was once a common framing material, but it
has steadily lost popularity for number of reasons.
The main disadvantage of wood is that it
deteriorates over time.

26. Covering Material
• Glass
• Acrylic
• Polycarbonate
• Polyethylene (double layer)
• Fiberglass

27. Procedure of GH Erection
• Mark a 4m × 20m rectangular area on the site, preferably
orienting the longer dimension in east-west direction. This
rectangle will act as the floor plan of the greenhouse.
• Mark four points on the four corners of the rectangle.
• Start from one corner point and move along the length of
marked rectangle, marking a point every 1.25 m distance until
reaching the other corner (16 bay; 17 points). The same
procedure is repeated on the other side of the rectangle.
• Dig 10 cm diameter holes up to 70 cm depth on all marked
points with the help of bucket auger or a crowbar. This way a
total of 34 holes on both the parallel sides of the greenhouse
floor is obtained.

28. • Poly grip sections formed according to the drawing into two 20m
length.
• Fix the prefabricated poly grip channels to the foundation pipes at
1.25 m spacing with the help of 6 mm diameter bolts.
• Set these assemblies on temporary supports between the holes
with the foundation pipes hanging vertically in the holes.
• Pour cement concrete mix of 1: 3: 6 around foundation pipes in
such a way that the lower 15 cm to 20 cm ends are covered in
concrete. The concrete is compacted around the foundation pipes
with the help of the crowbar and is allowed to cure for 2-3 days.
• After curing, fill the soil around the foundation pipes to the ground
level and compact it well.
• Position end frames on the two ends. Mark the position of legs and
dug holes for fixing of legs. Now install both the end frames.

29. • Put all the hoops in the foundation pipes in such a way that
straight portion of hoop is inserted into the foundation and rests
on the bolt used for fixing of poly grip channel .
• Take a 20 m long ridge line by spacing 15 mm diameter pipes
together. Put the 20m long pipe at the ridge line of the hoops.
• Use cross connectors on the ridge line pipe, in such a way that
one half of it remains on the one side of the hoop and the other
half on the other side.
• Put two bolts of 6 mm diameter in the holes provided in the ends
of cross-connector. Tie a few of them with the help of nuts.
• Repeat the same procedure for joining all the hoops with ridge
line pipe.

30. • Spread polyethylene film over the structure from one
end to the other end without wrinkles and keeping the
edges together.
• Place polyethylene film between the poly grip channel
and right angle strip and secure them under pressure
with the help of iron rods.
• The film is stretched gently and fixed on the other
parallel side by poly grip. This way the polyethylene is
secured on both the longer sides.

31. • On the other two remaining ends, polyethylene is
nailed to the end frames using wooden battens and
nails.
• The remaining portion of the end frames is covered
with polyethylene film, which is secured with wooden
battens and nails.
• Mechanical ventilation, heating and cooling
equipment is installed on the frames as per the
cropping requirement.

32. Material required for a greenhouse having 4m×20 m floor area
Material Specification Quantity
GI pipe Class A 25 mm dia, 85 cm long 30 m total
GI pipe Class B 15 mm dia, 6 m long 21 Nos
GI Sheet 20 gauge, 90×40 cm 4 sheets
MS flat 25×3 mm size 4 m
Lateral support to end frames 10 mm dia rod 10 m
Cement concrete 1:3:6 mix 1 m3
UV stabilized LDPE film Single layer 800 gauge, 5.4
m2/kg
154 m2
Polygrip
Channel 2000×3.5×4 cm 2 Nos.
Angle 2000×2×2 cm 2 Nos.
Key 6 mm dia, 56 mm length As per requirement
Wooden end frames 5×5 cm wood 0.15 m3
Nuts and bolts 8 mm dia, 35 mm long 70 sets
Miscellaneous items like nails,
hinges and latches
As per requirement

33. A four feet diameter ventilation fan is
installed in the East wall of each
greenhouse bay.

34. So-called curtain walls (four feet
high) are installed around the
outside perimeter wall of the
greenhouse. The bottom foot of
the walls is dug into the ground to
make for an effective heat-loss
barrier.

35. One by one, the panes of glass are
secured to the roof of the greenhouse.
Each pane is secured at the ridge first,
and at the gutter last. Rubber strips
are inserted between the glass and
the greenhouse frame.

36. The curvature of the glass
is possible due to the fact
that the glass is tempered.
This curvature adds
additional strength to the
roof construction.

37. The ventilation inlet window is
located along the entire West
wall of the greenhouse. The
external frame is needed to
support the opening and closing
mechanism of the window.

38. Shade curtains are installed to be
able to reduce the amount of solar
radiation reaching the plants during
the brighter summer months. The
curtain also acts as an energy
shield when it is closed during the
night in order to prevent warm air
from rising and cooling against the
cold glass roof

39. High-pressure sodium luminaires
(with 600-watt lamp bulbs) are
installed in the greenhouse. A total
of 144 luminaires is installed over
the total growing area of 6640
square feet (one lamp for every 46
square feet). The distance between
the top of the plant canopy and the
bottom of the luminaires is 10.5
feet.

40. Vertical airflow fans are installed to blow
greenhouse air directly onto the lettuce
crop. This air movement is needed to
help prevent tip burn (a physiological
disorder in lettuce plants, comparable to
blossom end rot affecting tomato). The
extra air movement increases plant
transpiration, resulting in increased
uptake of water and nutrients (including
Calcium, which plays a major role in the
occurrence of tip burn).

41. An evaporative cooling pad was installed
along the entire ventilation inlet opening
in the West wall of the greenhouse. On
warm days, the pad is wetted and the
incoming air is cooled as it passes
through the pad and water evaporates
into the incoming air.

42. A pump and plumbing system is installed to
pump water from and (outside) storage tank
onto the evaporative cooling pad. The excess
water is drained and returned to the storage
tank.

43. A storage tank for the evaporative
cooling water is installed just outside the
greenhouse. This tank will only be used
during the warmer summer months and
is drained and cleaned before the winter
season.

44. Thank You