Cladding materials

Question 1

what is the purpose of cladding materials?

Answer 1

prevent draughts
prevent rain entering structure
withstand weight of snow in winter
withstand the force of high winds

Question 2

what wave of radiation do plants give off?

Answer 2

long wave - we use glass as a cladding material as it traps it :)

Question 3

what wavelength of radiation does natural light give off?

Answer 3

short - glass permits entry of this and plants/soil absorb it.
It is then re-radiated as long wave

Question 4

describe the greenhouse effect

Answer 4

long wave radiation cannot pass through glass
(the plants radiate it out of them)
therefore the glass reflects it back into the greenhouse.

Question 5

how thick is horticultural glass and what percentage of natural light does it let through?

Answer 5

3mm thick
90% visible light

Question 6

what gauges does polythene come in and what percentage of visible light transmits through?

Answer 6

600 and 720gauge

85% visible light.

Question 7

Describe PVC as a cladding material

Answer 7

lasts 5 - 6 years
retains more radiation than polythene
allows 85% LTF

Question 8

describe double glazing as a cladding material

Answer 8

costly
added weight means a much stronger structure
reduces heat loss

can use with polythene sheets but condensation forms so reduced light transmission

Algal growth can occur if condensation not allowed to dry out which is even worse for light transmission

Question 9

describe acrylic sheeting

Answer 9

strong
good insulation/light transmission properties
Can be bent into curves

Large amount of contraction/expansion with temps
Can last up to 15 years

Question 10

what are the positives of using protective structures?

Answer 10

longer growing season
protection from Blight and Cold
Wider choice of plants available

Question 11

What are the negatives of using protective structures?

Answer 11

closer control of humidity needed
costly to but structure
Structure needs maintenance
Irrigation needs to be provided