GREENHOUSE GLAZINGS
Glass
Film Plastic
Rigid-Panel
GLASS
Float-1/8” double strength common in US
Light Transmission:
Single Layer = 88%-94%
Double Layer= 77%
High air filtration
High thermal conductivity
Lower relative humidity
$2.00-$7.00 ft2
Low impact resistance
Life Span = 25+years
PLASTIC FILMS
Polyethylene
Vinyl
Polyvinyl Fluoride
Polyester
Tefzel
PLASTIC FILMS
POLYETHYLENE
Major film used in the US
6-mil exterior / 4-mil interior layers (double
layer for insulation)
UV inhibitors increase life span; 3 to 4 year
life
Antifog materials =
less condensation problems
IR blockers =
less heat loss
PLASTIC FILMS
POLYETHYLENE
Costs (per layer)
6¢/ft2 for 3-year film (UV inhibitor added)
 7¢/ft2 for 3-year + antifog
 8¢/ft2 for 3-year + IR blocker
 9¢/ft2 for 3-year + antifog + IR blocker
 Labor to recover = 12¢/ft2 to 23¢/ft2 of
ground area covered by greenhouse (not
of roof area)

PLASTIC FILMS
VINYL
Polyvinyl Chloride
8 and 12 mil films (4 and 5 year life)
21.5¢/ft2 for 12 mil
Static charge is bad
Used in Japan
PLASTIC FILMS
POLYVINYL FLUORIDE
Tedlar
95¢/ft2 for 4 mil / 2 mil tube
PLASTIC FILMS
POLYESTER
Mylar
Too expensive for glazing but is used for
shade cloth material
PLASTIC FILMS
TEFZEL T2
Ethylene tetrafluoroethylene
Should last 20 years
95% light transmission for single layer
91% light transmission for double layer
More IR loss than polyethylene
$1.20/ft2 (but lasts 20 years)
Use limited by 50-inch width limit right now
RIGID-PANEL
Polyvinyl Chloride
Fiberglass-Reinforced Plastic (FRP)
Acrylic and Polycarbonate
RIGID-PANEL
POLYVINYL CHLORIDE (PVC)
Has been phased out for the most part
2+ year life span
4x the cost of polyethylene film
Light exposure = dark and brittle
RIGID-PANEL
FIBERGLASS-REINFORCED PLASTIC
(FRP)
more popular in past
5-20 yr. life expectancy, depending on
grade
panels flexible enough to conform to the
shape of quonset frames
transmits 88-90% PAR
-$1.00 ft2
RIGID-PANEL
FIBERGLASS-REINFORCED PLASTIC
(FRP)
more resistant to breakage than glass
light distribution more uniform than glass
because
less expensive to cool (20% less than glass)
fewer structural members than
glass
FRP surface subject to etching
by dust abrasion
glass lasts indefinitely, FRP
may last half lifetime of grower
RIGID-PANEL
ACRYLIC AND POLYCARBONATE
Double or triple-layer
10 yr. Life
Often coated to prevent condensation
drip; acrylic coating on polycarbonate
slows UV degradation
Corrugated Polycarb
RIGID-PANEL
ACRYLIC AND POLYCARBONATE
Used for glazing side and end-walls
8mm-16mm thick, thinner can be
bent, thicker cannot
Acrylic-83% PAR;
Polycarbonate-79% PAR
Acrylic-$2.10 ft2
Polycarbonate-$1.60 ft2
Acrylic