CONSTRUCTION OF GREENHOUSE

BIRSA AGRICULTURAL UNIVERSITY
Protected Cultivation and Secondary
Agriculture
LECTURE 10: CONSTRUCTION OF GREENHOUSE
BY
DR. PRAMOD RAI
DEPARTMENT OF AGRICULTURAL ENGINEERING

Materials for construction of greenhouse (GH)
Structure materials
Cladding materials
Gadget for environmental control

GH type based on cost of construction or
technology
Low cost or low tech GH
Medium cost or medium tech GH
High cost or hi-tech GH

Structu
re &
Glazin
g
Environment Culture
method
Expected
yield of
tomato
(kg/m2/yr)
Investme
nt cost
(Rs./m2)
Canopy Root
Bambo
o or
Wood
Single
layer
Passive
cooling
(roof and
side wall
vents)
No
heating
Soil
Drip
irrigation
with
manual
control
Med-
high
wire
10 – 20 300-500
Low cost or low tech GH

Structure
&
Glazing
Environment Culture
method
Expected
yield of
tomato
(kg/m2/yr)
Investmen
t cost
(Rs./m2)
Canopy Root
Steel
frame
Double
PE film or
rigid
plastic
Passive/A
ctive
cooling
(vents+pa
d/fan)
With or
without
air heating
Basic
level of
computer
control
Soil or
soiless
substrate
Drip
irrigation
Some
control
High
wire
culture
Longer
season
Usually
computer
ized
fertigatio
n
25 – 50 500 –1500
Medium cost or medium tech GH

Structure
&
Glazing
Environment Culture
method
Expected
yield of
tomato
(kg/m2/yr)
Investment
cost
(Rs./m2)
Canopy Root
Steel or
Aluminu
m frame
Glass,
polyethyle
ne or
Polycarbo
nate
Forced
ventilation
+
evaporativ
e cooling +
hot water
pipe
heating +
CO2
enrichment
+ shading
(light) +
energy
blanket
Soilless
substrate
Drip
irrigation
with full
automated
control
(EC
control
according
to light
intensity)
High wire
culture
Fully
computeri
zed
fertigation
Recirculat
ion
Hydroponi
cs
50 – 75
More than
1500
High cost or high tech GH

Greenhouse Construction Materials
Low cost greenhouse
S. N. Materials Purpose Photographs
Structural Materials
1. Bamboo Used for structural
components like column,
beam, truss, etc.
2. Wood Used for structural
beam, truss, etc.
3. Concrete pillars Used for column only.

Cladding Materials
1. UV
stabilized
poly film
Used for cladding GH to
create favorable micro
climate inside the structure.
2. Shade net Used for reducing the solar
radiation inside GH.
3. Insect proof
net
Used as cladding material to
check the entry of insects
inside the structure.
4. Profile with
spring lock
To fasten the covering
materials with structure.
.

Miscellaneous
1. Wire To fasten the structural
members with each other.
2. Coal tar For preservation of bamboo
and wood from decay.
3. PVC pipe Put the bottom of the
bamboo pole inside the pipe
and then put in the soil. It
will prevent the bamboo
from termite attack and other
decay.
4. Waste
plastic
mulch
Wrap the bottom of the
bamboo pole with the waste
plastic to prevent decay due
to moisture.
.

Medium cost greenhouse
1. GI Pipe Used for structural
beam, truss, etc.
2. Gutter To drain out the rain water
from the roof of the
greenhouse.
3. GI cable To support the shade net or
aluminates in the greenhouse

Cladding Materials
1. Multilayer
UV
stabilized
poly film
2. Different
color Shade
net
Used for reducing the solar
3. Insect proof
net
4. Profile with
spring lock
To fasten the cladding
.

Gadgets for environment control
1. Exhaust fan
with pad
To decrease the air
temperature in GH by
evaporative cooling.
2. Foggers To increase the humidity and
decrease the air temperature
inside the GH.
3. Misters To increase the humidity
within the micro climate of
the plants.
.
.

Miscellaneous
1. Nut and
bolts
To fasten the structural
members with each other.
2. Thermal
screen
Thermal screens allow to
control light & temperature
more precisely, It is designed
to keep the heat inside the
structure.
.

High cost greenhouse
1. GI Pipe Used as structural
beam, truss, etc.
2. Gutter To drain out the rain water
from the roof of the GH.
3. GI cable To support the shade net or
aluminates in the GH.

Cladding Materials
1. Multilayer
UV stabilized
poly film
2. Polycarbonate
sheet
Used for cladding GH.
3. Glass Used for cladding GH.
4. Different
color Shade
net
Used for reducing the solar
.

Cladding Materials
5. Insect proof
net
6. Profile with
spring lock
To fasten the covering
7. Floor
covering
Used for floor covering to
prevent fungal development.
8. Thermal
screen
Thermal screens allow to
control light & temperature
more precisely, It is designed
to keep the heat inside the
structure.
.

Gadgets for environment control: Cooling
1. Exhaust fan
with pad
To decrease the air
temperature in GH by
evaporative cooling.
inside the GH.
3. Misters To increase the humidity
within the micro climate of
the plants
4. Exhaust fan Pull out the hot air from
inside the GH to bring down
the temperature.
.

S. No Materials Purpose Photographs
Gadgets for environment control: Cooling
5. Roof
evaporative
cooling
Sprinkling of water onto a
surface of the roof so as to
form a thin layer.
Water temperature fall to the
wet bulb temperature of the
closely surrounded air.
6. Painting of
GH roof
with
hydrated
Calcium
oxide
It reduces both the
temperature & the light
intensity.
7. Shading nets It will diffuse light rays &
reflect heat, come either in
white or green and can be
thinned using paint solvent.
.

Gadgets for environment control: Heating
1. Unit heaters They can provide uniform bench
top temperatures as well as under
the bench temperature.
2. Central Heating
(hot water
system)
Steam or hot water is produced,
plus a radiating mechanism in the
GH to dissipate the heat.
3. Central Heating
(steam heating
system)
4. Radiant heater
system
These heaters emit infrared
radiation, which heat objects such
as plants, walks and benches, they
will warm the air surrounding
them.
.

Gadgets for environment control: Lighting
1. High Intensity
Discharge
lamps
It generates the
supplemental lighting in the
GH.
2. Metal Halide
lamps
They provide the best
overall spectral distribution
of all horticultural lamps.
3. High Pressure
sodium lamps
Used for commercial
supplemental lighting in
horticulture. They are the
most efficient in the PAR
range with the exception of
low pressure sodium lamps.
4. Incandescent
lamps
They are not very light
efficient and a relatively
short lamp life, it is usually
not the most effective
radiation sources.
.

Gadgets for environment control: Lighting
5. Fluorescent
lamps
It produce light from the
excitation of low pressure
mercury vapor in a mixture
of inert gases.
They are more light efficient
than incandescent lamps and
have much longer life span.
Gadgets for environment control: Inside air circulation
1 Axial fan It accelerate the air
movement inside the
greenhouse to maintain the
uniform temperature and
RH.
.

Gadgets for environment control: CO2 enrichment
1. CO2
generator
(Inside)
To Increase the CO2 level
inside the GH structure.
2. CO2
generator
(Outside)
inside the GH structure.
3. CO2
cylinder
inside the greenhouse
structure.
.

Gadgets for environment control: Relative humidity
1. De-
Humidifier
To decrease the humidity.
2. Humidifier To decrease the air
temperature by increasing
the humidity.
inside the GH.
.

Miscellaneous
1. Nut and
bolts
To fasten the structural
members with each other. .

Growing media
1. Vermi
Compost
Organic manure for soil less
cultivation.
2. Coco pit Organic manure for soil less
cultivation.
3. Vermiculite Organic manure for soil less
cultivation.
4. Growing
bag
Used for soil less
cultivation.
.

Gadgets used in greenhouse (GH)

Temperature
One side registers the maximum temperature and other
side records minimum temperature. The bend at the
bottom of the thermometer contains mercury which
moves up or down based on the expansion and
contraction of alcohol.
When the temperature rises, the alcohol expands and
pushes the mercury up the maximum column. This also
pushes the mercury down in the minimum column.
Similarly, when the temperature falls, the alcohol
contracts and pulls the mercury up in the minimum
column resulting in a fall of mercury in the maximum
column.
The steel indexes are located on the surface of mercury.
They move along with the flow of mercury up and
down. When temperature reaches its maximum and
minimum limits, the metal indexes remain at the place.
This helps in recording the maximum and minimum
temperature of the day.
Digital thermometers are becoming more
common. They are easier to read, offer remote sensing
capabilities in hard-to-reach areas, and sometimes have
data logging capabilities.

Surface Temperature
In cases where large differences in temperature exist between GH plants and
surrounding surfaces such as walls, glazing and floor, the radiant temperature
of those surfaces can influence the effective plant temperature.
An infrared thermometer measures surface temperature. This is a line-of-sight
instrument and detects the radiant temperature of object(s) it can see.
Infrared thermometers employ a lens
to focus the infrared light emitting
from the object onto a detector known
as a thermopile.
The thermopile absorbs the infrared
radiation and turns it into heat. The
more infrared energy, the hotter the
thermopile gets. This heat is turned
into electricity. The electricity is sent
to a detector, which uses it to
determine the temperature of whatever
the thermometer is pointed at.

Humidity
The traditional way to measure relative humidity is a
two-step process: First obtain wet bulb and dry bulb
temperatures, and then convert it to relative humidity
using a psychrometric chart.
The dry bulb temperature is commonly measured with a
standard thermometer. The wet bulb temperature is
determined from a standard thermometer modified with a
wetted fabric wick covering the sensor bulb.
The adiabatic evaporation of water from the thermometer
bulb and the cooling effect is indicated by a wet bulb
temperature lower than the dry bulb temperature in the
air.
Relative humidity can be measured directly by using
hygrometer. Digital hygrometers determine relative
humidity with solid-state devices and electronics.
The sensor is a matrix material in which electrical
properties change as water molecules diffuse into or out
of the matrix material in response to water vapour
content.

Lux meter
Lux is a measurement of the overall intensity of light within an environment for
any given area or distance from the source or lux is the amount of light in
an environments perceived by the human eye.
In other words, the lux is a unit of measurement of brightness, or more
accurately, illuminance.
A lux meter is a device for measuring brightness. It specifically measures the
intensity with which the brightness appears to the human eye. This is different
than measurements of the actual light energy produced by or reflected from an
object or light source.
A lux meter works by using a photo cell to capture light.
The meter then converts this light to an electrical current. In
turn, the amount of current depends on the light that strokes
the photocell or light sensor.
Lux meters read the electrical current, calculate the
appropriate value, and shows this value on its display.

Air speed
Air speed is measured with an anemometer.
Vane type anemometer [Suitable for air speed (>50 fpm)]
Hot-wire anemometer [Suitable for air speed (<50 fpm)]
A vane type anemometer is more rugged and usually less expensive than a
hot-wire anemometer. It is well suited to measure high speed air. Designs
vary, but most have a three inch-diameter vane propeller, which starts turning
when the propeller is held in an air stream.
In modem instruments the speed of rotation of the
vane is sensed and measured electronically and
the air speed, which is a function of the speed of
rotation of the vane, is indicated on a meter.
Vane anemometers do not measure low air speeds
because the mass of the vane requires a fair
amount of air movement to induce rotation.
Vane anemometers are not considered accurate
below 50 to 60 fpm, even though the meter
displays a velocity at these low air speeds.
Vane type anemometer

A hot-wire anemometer has a very fine, short wire, often the thickness of a
human hair, positioned between two supports which incorporates a
temperature-sensing thermistor. The wire is heated by electronic circuitry and
air flowing over the wire causes its temperature to decrease.
By detecting this temperature decrease, or
by evaluating the amount of current
supplied to keep the temperature of the
wire from decreasing, the anemometer
determines the speed of the passing air.
A hotwire anemometer is the instrument
of choice for low air speed
measurements. Air that is virtually still
(<50 fpm) exists in many GH, especially
away from ventilation inlets and outlets.
Due to their small size, it can be used in
small places.
Air speed
Hot-wire anemometer

Portable CO2 monitor
Plants use carbon dioxide (CO2) in a process called photosynthesis, GH
growers frequently increase plant production through supplementation of
carbon dioxide in the GH environment. The ambient carbon dioxide
concentration is around 350 to 400 ppm. Growers usually enrich the GH
environment to a level of around 1,000 ppm.
CO2 sensor involves the gas being pumped or diffused into the light tube.
The electronics then measure the absorption of the characteristic wavelength
of light. The amount of light absorption is converted into an electrical output
that provides a parts per million (ppm) or % volume measurement.
Continuous monitoring of CO2 concentration is
done as part of some GH environmental control
systems using CO2 monitor.
The difference between the amount of light
radiated by the IR lamp and the amount of IR
light received by the detector is measured. Since
the difference is the result of the light being
absorbed by the CO2 molecules in the air inside
the tube, it is directly proportional to the number
of CO2 molecules in the air sample tube.

Sunshine Recorder
A sunshine recorder is a device that records the amount of sunshine at a
given location or region at any time. Sunshine recorder is used to measure
the duration in hours of bright sunshine during the course of the day.
It essentially consists of a glass sphere mounted in a section of spherical
brass bowl with grooves for holding the recorder cards.
The hours of bright sunshine are recorded by the rays of the sun passing
through the sphere, which undergo focus and burn a hole through the card
placed behind it. The card itself is calibrated so that the hours and minutes of
the day are measured across it.
There are set of grooves for taking
three sets of cards, long curved for
summer, short curved for winter and
straight cards at equinoxes.
The sphere burns a trace on the card
when exposed to the sun, the length of
trace being a direct measure of duration
of bright sunshine.

Pyranometer
A pyranometer is an instrument for the measurement of the solar radiation
received from the whole hemisphere. It measure global irradiance, the
amount of solar energy per unit area per unit time incident on a surface of
specific orientation emanating from a hemispherical field of view. The
global irradiance includes direct sunlight and diffuse sunlight.
The working principle of the it mainly depends on the difference in
temperature measurement between two surfaces like dark and clear. The
solar radiation can be absorbed by the black surface on the thermopile
whereas the clear surface reproduces it, so less heat can be absorbed. The
thermopile plays a key role in measuring the difference in temperature. The
potential difference formed within the thermopile is due to the gradient of
temperature between the two surfaces. These are used to measure the sum of
solar radiation.
The solar radiation spectrum that
reaches earth's surface extends its
wavelength approximately from
300 nm to 2800 nm, 97% of the sun’s
spectral distribution “total solar”
radiation. Units are W m-2.

Net Radiometer
A net radiometer is a type of actinometer used to measure net radiation (NR)
at the Earth's surface for meteorological applications. The name net
radiometer reflects the fact that it measures the difference between
downward/incoming and upward/outgoing radiation from Earth.
It is based on a thermopile sensor whose warm joints are in thermal contact
with the receiver while the upper cool joints are in thermal contact with the
lower receiver. The temperature difference between the two receivers is
proportional to the net irradiation.
The temperature difference between
hot and cold junction is converted
into a voltage by Seebeck effect. The
two receivers are made from a
portion of spherical coated Teflon.
The particular form of the two
receivers provides a response in
accordance with the cosine.

Spectroradiometer
It splits incoming radiation into individual wavelengths or prescribed
wavebands, then measures the irradiance (energy) of the photons. It
measures spectral irradiance as µMolm-2s-1 nm-1or Wm-2nm-1 .
Spectrometers discriminate the wavelength based on the position the light hits
at the detector array allowing the full spectrum to be obtained with a single
acquisition.
Most spectrometers have a base measurement of counts which is the un-
calibrated reading and is thus impacted by the sensitivity of the detector to
each wavelength. By applying a calibration, the spectrometer is then able to
provide measurements of spectral irradiance, spectral radiance and/or spectral
flux.
This data is also then used with built in or
PC software and numerous algorithms to
provide readings or Irradiance (W/cm2),
Illuminance (lux), Radiance (W/sr),
Luminance (cd), Flux (Lumens or Watts),
Chromaticity, Color Temperature, Peak
and Dominant Wavelength.

LAI meter
Leaf area index (LAI) is a measure for the total area of leaves per unit
ground area and directly related to the amount of light that can be
intercepted by plants. It is an important variable used to predict
photosynthetic primary production, evapotranspiration and as a reference
tool for crop growth.
Leaf area index (LAI) quantifies the
amount of leaf material in a canopy. By
definition, it is the ratio of one-sided leaf
area per unit ground area.
It is a lightweight, portable, linear array of
photosynthetically active radiation (PAR)
sensors for non-destructive measurements
of leaf area index. It allows you to measure
canopy PAR interception and calculate
LAI at any location within a plant or forest
canopy.

Soil thermometer
Mercury-in-glass thermometer are used for this purpose. The bulb is inserted
into a hole in the ground with the stem lying along the surface. A
thermometer that has been fused into an outer protecting glass shield is used
for measurement at greater depths. To obtain a measurement, the instrument
is lowered into a steel tube that has been driven into the soil to the desired
depth.
Digital soil thermometers are also used for measurement of soil temperature.
A soil temperature thermometer can perform a
measurement in five steps:
1. Determine the proper depth to perform the
measurement.
2. Use a screwdriver to make a pilot hole. This
ensures that the thermometer’s probe will not be
damaged if forced into hard soil.
3. Insert the thermometer into the pilot hole.
4. Provide shade if the sun is bright. This ensures that
the reading is accurate.
5. Take a reading in the morning and late afternoon,
and then average out the results.

Pollinator
Pollination is a process where the pollen from the male parts of the flower are
transferred to female flower or female parts of the flower. This process has to
happen for the fruit setting.
In nature, this happens in multiple ways. Bees do most of the pollination and
pollination by wind also happens. But when you are growing plants in a GH or
a closed environment where bees can’t enter and there is not a lot of wind, the
grower needs to help in the pollination process.
To assist pollination in your GH, you need a pollinator that can be used to
pollinate flowers that have their male and female parts in the same flower.
This flower pollinator is a simple tool that causes vibration of the flower
stalk resulting in pollination.

Tensiometer
A tensiometer is a device for measuring soil water
tension. It consists of a cylindrical pipe about one
inch in diameter with a porous ceramic cup attached
to one end and a vacuum gauge attached to the other.
It indirectly measure soil moisture tension.
Tensiometer readings are easily interpreted and
indicate the soil water conditions experienced by the
plants’ roots.
To measure soil water tension, the end of the
tensiometer with the porous cup is inserted through a
pilot hole in the soil, which has been made with a soil
probe.
After installation the tensiometer is filled
with water and allowed to equilibrate with
the soil water for about twenty-four hours.
Tensiometers should be installed in the zone
of greatest root density, at about one-quarter
to one-third of the maximum root depth.
Tensiometer indicate when to irrigate, but not
how much to irrigate.

Daily light integral (DLI) meter
Daily light integral (DLI) describes the number of
photosynthetically active photons (individual particles
of light in the 400-700 nm range) that are delivered to a
specific area over a 24-hour period.
This variable is particularly useful to describe the light
environment of plants.
DLI is usually calculated by measuring
the photosynthetic photon flux density (PPFD) in
μmol·m−2·s−1 (number of photons in the PAR range
received in a square meter per second) as it changes
throughout the day, and then using that to calculate total
estimated number of photons in the PAR range received
over a 24-hour period for a specific area.
In other words, DLI describes the sum of the per second
PPFD measurements during a 24-hour period.

If you have any question/suggestion
Mail me: pramod_kgp@yahoo.co.uk
Contact me on WhatsApp: 8986644713

CONSTRUCTION OF GREENHOUSE

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