GREENHOUSE GLAZINGS

GlassFilm PlasticRigid-Panel

GLASSFloat-1/8” double strength common in US Light Transmission: Single Layer = 88%-94%Double Layer= 77%High air filtrationHigh thermal conductivity Lower relative humidity$2.00-$7.00 ft2

Low impact resistanceLife Span = 25+years

PLASTIC FILMS

PolyethyleneVinylPolyvinyl FluoridePolyesterTefzel

POLYETHYLENEMajor film used in the US6-mil exterior / 4-mil interior layers (double layer for insulation)UV inhibitors increase life span; 3 to 4 year lifeAntifog materials = less condensation problemsIR blockers = less heat loss

PLASTIC FILMS

POLYETHYLENECosts (per layer)6¢/ft2 for 3-year film (UV inhibitor added)7¢/ft2 for 3-year + antifog8¢/ft2 for 3-year + IR blocker9¢/ft2 for 3-year + antifog + IR blockerLabor to recover = 12¢/ft2 to 23¢/ft2 of

ground area covered by greenhouse (not of roof area)

PLASTIC FILMS

VINYLPolyvinyl Chloride8 and 12 mil films (4 and 5 year life)21.5¢/ft2 for 12 milStatic charge is badUsed in Japan

PLASTIC FILMS

POLYVINYL FLUORIDETedlar95¢/ft2 for 4 mil / 2 mil tube

PLASTIC FILMS

POLYESTERMylarToo expensive for glazing but is used for shade cloth material

PLASTIC FILMS

TEFZEL T2

Ethylene tetrafluoroethyleneShould last 20 years95% light transmission for single layer91% light transmission for double layerMore IR loss than polyethylene$1.20/ft2 (but lasts 20 years) Use limited by 50-inch width limit right now

PLASTIC FILMS

RIGID-PANEL

Polyvinyl ChlorideFiberglass-Reinforced Plastic (FRP)Acrylic and Polycarbonate

POLYVINYL CHLORIDE (PVC)Has been phased out for the most part2+ year life span4x the cost of polyethylene filmLight exposure = dark and brittle

RIGID-PANEL

FIBERGLASS-REINFORCED PLASTIC (FRP)

more popular in past5-20 yr. life expectancy, depending on gradepanels flexible enough to conform to the shape of quonset framestransmits 88-90% PAR-$1.00 ft2

RIGID-PANEL

FIBERGLASS-REINFORCED PLASTIC (FRP)

more resistant to breakage than glasslight 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 abrasionglass lasts indefinitely, FRP may last half lifetime of grower

RIGID-PANEL

ACRYLIC AND POLYCARBONATEDouble or triple-layer 10 yr. LifeOften coated to prevent condensation drip; acrylic coating on polycarbonate slows UV degradation

RIGID-PANEL

Corrugated Polycarb

ACRYLIC AND POLYCARBONATEUsed for glazing side and end-walls8mm-16mm thick, thinner can bebent, thicker cannotAcrylic-83% PAR; Polycarbonate-79% PARAcrylic-$2.10 ft2

Polycarbonate-$1.60 ft2

RIGID-PANEL

Acrylic