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Greenhouse Structures

Greenhouse Structures. Identify the different types of greenhouses and their arrangements. Greenhouse Range- Two or more greenhouses side by side Attached Greenhouse- Connected to building, floral shop, garden center, office, home, ect. Attached Even-span, window mounted, lean-to

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Greenhouse Structures

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  1. Greenhouse Structures

  2. Identify the different types of greenhouses and their arrangements • Greenhouse Range- Two or more greenhouses side by side • Attached Greenhouse- Connected to building, floral shop, garden center, office, home, ect. • Attached Even-span, window mounted, lean-to • Freestanding- Separate from other buildings • Even-span, uneven –span, Quonset, Gothic arch • Connected Greenhouse- Does not include sidewalls within structures • Gutter-connected, dutch, barrel vault, sawtooth

  3. Match the greenhouse structures with their advantages. • Attached: • Less construction material • Can be used to head and cool homes • Attached Even-span • More available space • Free standing: • Maximum sunlight available for plants • Allow regulation of many different types of plant environments

  4. Match the greenhouse structures with their advantages Cont. • Freestanding • Even-span • Allows more freedom of space/ Movement and equipment • Connected: • Less construction material • Less land needed • Heat conservation due to less exposure • Workers and equipment can move through buildings

  5. Describe the internal structures and equipment of a greenhouse • Frame • Pressure –treated wood • Aluminum • Galvanized steel • Note: Glass green houses require more structural support that polyethylene • Foundation • Continuous concrete bed upon which greenhouse is built • Water and electrical lines are place

  6. Describe the internal structures and equipment of a greenhouse cont. • Concrete Footings • Non-continuous supports located below the frost line (cannot be affected by frost heaves). • Take the place of foundation • Spaced at intervals according to placement of support anchor posts • Sidewalls • Between the footings and supports • Holding greenhouse covering in place

  7. Describe the internal structures and equipment of a greenhouse cont. • Common components of greenhouses: • Ridge – Top of greenhouse; runs the length of the house • Anchor support posts – Provides structural support • Trusses – Adds structural support • Consists of rafters, chords, and struts • Purlins – run the length of the greenhouse, bolted to each truss and adds structural support • Ventilators – attached to the sides or ridge of the greenhouse these open to allow ventilation

  8. Describe the internal structures and equipment of a greenhouse cont. • Greenhouse covering • Glass • Provides excellent light transmission • Long lasting • Double strength, grade B weight used for greenhouse except in cold areas • Expensive installation and heating • Requires good structural support of aluminum or steel

  9. Describe the internal structures and equipment of a greenhouse cont. • Greenhouse covering • Polyethylene • Inexpensive installation • Low heating cost • Short-lived • UV inhibitors increase its life span • Produces condensation which increases wet plant foliage and disease possibilities • Light reduction compared to glass

  10. Describe the internal structures and equipment of a greenhouse cont. • Greenhouse covering • Corrugated Fiberglass – Reinforced Plastic • Low in cost • Ease of installation • Tensile strength • Longer lifespan • Good light penetration • Can degrade over time from ultraviolet damage, dust & pollutants • Flammable and may increase insurance costs

  11. Describe the internal structures and equipment of a greenhouse cont. • Greenhouse covering • Acrylic • Light weight • Ease of installation • Good lighting transmission • Long lifespan • Flammable

  12. Describe the internal structures and equipment of a greenhouse cont. • Greenhouse covering • Polycarbonate • Lightweight • Ease of installation • Good heat insulation • Good light transmission • Available in clear, corrugated single layer panels • Good replacement of corrugated fiberglass • Flammable

  13. Describe the internal structures and equipment of a greenhouse cont. • Interior & exterior design • Drives should be wide for trucks • Shipping and receiving doors should be accommodating to and from the drive • Parking for customers and employees • Location of offices should be easy to access from shipping area

  14. Describe the internal structures and equipment of a greenhouse cont. • Benches and Beds • In-ground beds- used for fresh florals • Raised benches- used for potted plants • Floor- used for potted plants. Surface is gravel for percolation and weed control • Three styles of concrete in-ground benches: • Longitudinal- runs length of greenhouse, used for in-ground beds • Cross-benches- runs the width, aisles run along sidewalls & between benches • Peninsular- Benches extend to sidewalls, aisles run down the center and between benches

  15. Describe the internal structures and equipment of a greenhouse cont. • Benches and Beds • Four types of raised benches • Wood bench fabric • Bench top consisting of wood connected by wire, rolled out over a bench frame, good for growing in large pots or flats • Welded • 14 gauge wire coated with plastic, with mesh of 1-2 inches, good for a variety of plants • Prefabricated plastic • Vinyl by the square foot, can be customized to fit the bench, good for growing large pots or flats • Movable (floating aisle) • 14 gauge galvanized wire on frames, mounted of steel rollers, rollers allow the bench to be movable to the right or left, this creates a need for only one aisle in the greenhouse.

  16. Describe the internal structures and equipment of a greenhouse cont. • Shading • Fabric • Black polypropylene pulled over the greenhouse to reduce light intensity and temperature, comes in a range of shades • Compound • Liquid compounds applied to glass or polyethylene covered greenhouse to reduce light intensity.

  17. Describe the internal structures and equipment of a greenhouse cont. • Aisles and walks • 3-4 feet wide • Concrete or gravel, depending upon the amount of use

  18. Heating • Night Temp: 55-650 F (min 40 - max 850 F) • Max. Day Temp: 10-15 degrees higher • Consider: • Fuel Available • Size of Greenhouse • Operational Cost • Covering & # of Layers • Site of Greenhouse: Wind • Requires Min. Maintenance / Auto Operation

  19. Locate Thermostat at plant height w/ shade over top to avoid false readings • Vented Heaters: Down drafts caused by chimney not high enough to clear ridge of g.h.(at least 2’) open doors & vents can cause draft • HEATING SAFETY MARGIN: • Rule of thumb: for est. heat loss 1.2 BTU per hour for each degree of temp differential per sqft of exposed surface

  20. Describe the internal structures and equipment of a greenhouse cont. • Heating • Unit heaters- Can be fired by natural gas, propane, fuel oil, coal or wood. Electricity is not recommended.

  21. Types of Heating • Attached Structures: Extension of Home Heating System • Hot Water: Extend Pipes into Greenhouse • Hot Air: Add Ducts and Thermostats • Open Door and Fan Blow in House Heat • Free Standing Structures: • Space Heaters w/ Electric Fans • Low Cost for Small Greenhouse • Force Hot Air Heaters • Heater w/ air circulation system & chimney • PLASTIC PUNCHED TUBE • HORTIZONTAL AIR FLOW FANS

  22. Hot Water or Steam Heat Piped in Greenhouse • More popular heating w/hot water in localized benches • Electric Heaters • Overhead heating + Soil heating cables • provides a localized plant environment which allows plants to thrive when surrounding air is lower than normal • Solar Heating • Use of black painted drums filled w/water to absorb heat & release it back into the environment

  23. Describe the internal structures and equipment of a greenhouse cont. • Cooling • Fan and Pad • Exhaust fan draws air through moist cellulose pad, air is cooled through evaporation, for dry air conditions • Fog Evaporative • Fog is generated within the greenhouse, heat is absorbed by the water droplets and evaporated, cooling the greenhouse environment, use in propagation houses.

  24. Cooling the Greenhouse • Ventilation & Circulation System • Roll up screens of wood • Lath available w/pulleys: decrease radiation 50% • Shade Cloth • uniform shade, exact degree of shade, light wt. & easy to install • Paint - On Shades: glass & polycarbornate • mix w/ water and spray on • remove w/ hot water & soap & brush

  25. Vinyl-Plastic Shading: • Rolls 55-65% shade apply by washing area & smoothing plastic on area • Fan & Pad: Evaporative Cooling • Moves air through a wet pad and it takes 1000 BTUs of heat to change 1lb of water to vapor = reduction of air temperature • Cooling capacity depends on the outside humidity • Equipment Needed: • PADS PUMP PVC PIPE • WATER TANK (1 GAL/ FT LENGTH OF PAD) • VENT

  26. MIST COOLING • SPRAY TINY WATER DROPLETS INTO AIR • REQUIRES MANY MIST HEADS OPERATED AT HIGH PRESSURE • PROBLEMS: • IF MIST CARRIES ANY MINERALS DEPOSITS CAN BE LEFT & DAMAGE FOLIAGE, WET FOLIAGE INCREASE DISEASE PROBLEMS

  27. Describe the internal structures and equipment of a greenhouse cont. • Ventilation • Natural • Air exchange is fostered through open ridge and side venting, under thermostat control. Not advised for winter cooling. • Fan tube • Fans bring in cool air which is mixed with the warm air and distributed through holes in plastic tubing that runs the length of the greenhouse.

  28. Ventilation • VERY IMPORTANT FOR AIR MOVEMENT • PLANTS GROW BETTER WHEN AIR IS CONTINUOUSLY CIRCULATING • COOLS & WARMS LEAF SURFACE PROVIDING UNIFORM TEMP. • REMOVES WARM MOIST AIR & REPLACES W/ DRIER AIR (DECREASE DISEASE) • DECREASE THE INSIDE TEMP DURING SUNNY DAYS • SUPPLIES CARBON DIOXIDE TO PLANTS

  29. Types of Ventilation • Need: • Ridge Vents: remove hot air at highest pt of greenhouse • Side Vents: side of the house to provide desirable air currents • Hand Operated Roof Vents • Automatic Ventilation System • Control by thermostat • Exhaust Fans: need to be large enough to have complete air exchange in 60 seconds

  30. Ridge Vents

  31. Ventilation Equipment • Ridge Vent • Exhaust Fan (1, 2 speed for small houses) • Vents in back of Greenhouse • Air Circulation: Poly Tube or Air Flow Fans • Horizontal Air Flow Fans: • Fans should operate continuously to push air horizontally on one side of house & in opposite direction on other side of house • Position Fans at least 12” from the Roof

  32. Horizontal Air Flow Fans

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