“Greenhouse Guts” Lecture Series

1. Feb 17 “Greenhouse Guts”Lecture Series Greenhouse Management & Floriculture Agriculture Technology Department Plymouth High School

2. To recognize and explain three kinds of equipment that can ventilate a greenhouse • To recognize and explain two kinds of equipment that can heat a greenhouse • To distinguish between the four types of greenhouse covering materials (glass, polycarbonate, polyvinyl chloride and polyethylene TARGETS LECTURE: Glazings ACTIVITY: Understand how the systems are used in the Plymouth HS Greenhouse Understand how the computer controls the GH climate. Discover the purposes of the head house

3. Covering (Glazing) Glass Acrylic Polycorbonates Vinyl (polyvinyl cholride) Polyethylene (#1 used)

4. G l a z I n g s Factors to Consider when choosing a Glazing • Capital available • Desired energy savings • Crop(s) grown • Period of time the GH is in operation • Natural environmental conditions • Above 80% light transmission is good • u-value • ability of heat to move through the product • Lower value (more heat trapped) • High value (more heat is lost) • #/ft2/hour • Strength of Glazing • Dead loads • Snow • Live loads • Google: National GH Manufacturing Association • NGMA: building codes

5. Glass • Thickness: - Single Strength: (SSB): 1/16” - Double Strength (DSB): 1/8” • Light transmission: 90% • u-value = 1.13 • Life Expectancy ???(no rocks through windows) • Cost: $3.50-7.00 per ft2 (what does this all include?)

6. Fiberglass Reinforced Polyester • Dimensions: -51 ½” wide, up to 24’ long • Cost ($.85-$1.75/ft) • 10-15 years life expectancy, UV light breaks down fibers, turning material yellow • u= 1.2 • 35% savings over glass • 88% light transmission (diffuses light) • Surface deteriorates

7. Acrylics • Trade names: • Exolite, Acrylite, Plexiglass, Lucite, Deglas • Holds 10-60 lbs/ft2 • Dimensions: - 5/8” thick, ¼” flexible • Light transmission: 83% • Build houses E-W • Heat: • u=.56-.6 • 40-50% savings over glass • Longevity: 10yr • Guaranty 30yr • Growers still getting same light penetration, do not yellow • Snow load • Flammability: can burn • $2-$4/ft2

8. B. Acrylics http://www.greenhousemegastore.com/Deglas-Acrylic-Panel-16mm-Clear/productinfo/CPC-DG16/

9. Impact Modified Acrylic • Used a lot in the hail belts in the US • Multi-wall • 85% light transmission • 10x impact strength of acrylic (hail zones) • Like acrylic

10. Polycarbonates • Tradenames: • Exolite, Lexsaon, Tuffak, Polygal, Primex,cryoflex, qualex, Twin Wall • ¼” thick to 5/8” thick • Width=48” Length= up to 32’ long sheets • U=.58 -.69 • (40-50% heat savings) • Good for 10yrs, light intensity, looses 1%/yr • Fire: self-extinguishing • Light: about 80% + 1% loss/yr • Snow: 25lbs/ft2 • Cost: $1.35, $3, $4 per ft2 • Coatings available • Anti-condensation • Acrylic for UV protection

11. Examples of glazing http://www.greenhousemegastore.com/Polycarbonate-Panels/departments/1034/?gclid=CKiiidvLvaQCFcPsKgod5hzwzw http://site.green-house-kit.net/GrnHouseGlazingMaterials.jpg&imgrefurl

12. Other coverings • Plastic Films • 2-8mils (.002” - .008”) • Vinyl (polyvinyl chloride) • 8-12 mil • $$$ • 4-5yrs • Static electricity • ETFE (ethylene Tetraflouoroethylene) • $$$ • Polyester • $$$ • Durable for 7 yrs www.farmwholesaleag.com http://www.stuppy.com/commercial.aspx

13. Polyethylene • Heat Savings: dbl= 40% • Dbl: stability against wind • Cost $.06 to .09/ft2 (about $5/ft2 for entire house) • # 1 Glazing Film used • Life Expectancy 3-4 yrs • Tradenames: Visqueen 1504, Arco Tufflite • Single layer or Double layer • Light Transmission • 67% double and 87% for single • Diffused light • u=1.1 ¾” to 8” spacing of too big =air currents (2” is optimum) .2 to .3 static pressure 6ml 4ml

14. END OF TODAY • Wednesday • Early Release