Class 2 Types of green house

Green house technology

1. TYPES OF GREENHOUSE

2. Types Based on Shape Based on Utility Based on Construction Based on number of Span Based on Environmental control Based on Covering/Cladding material Based on Cost of Construction

3. Based on Shape Lean to type greenhouse Even span type greenhouse Uneven span type greenhouse Ridge and furrow type Saw tooth type Quonset greenhouse

4. Lean to Type

5. This type of design is used when a greenhouse is to be constructed against the side of an existing building, so the plants can make the best use of sunlight and owner can minimizes the requirement of roof support Lean to type greenhouse

6. The design of a greenhouse depends upon the latitude of the place and the requirement of crop. Lean-to- type Useful where space is limited Least expensive, availability of water and electricity Advantages Disadvantages Temperature control is difficult Location of windows and doors on the supporting structure must be kept in mind 24

7. Even-span Greenhouses 7 This is the most common greenhouse in India The two roof slopes are of equal pitch and width.

8. Even-span – Advantages Provides more usable space and can be lengthened Can accommodate two to three benches for growing crops. Better shape for air circulation Disadvantage Most costly option 21

9. Uneven span type greenhouse 9 One roof wider than the other. Different pitch angles. Used on hillsides. Wider roof faces south for maximum solar gain.

10. Quonset Greenhouses 10 Framework consists of the pipe arches or trusses are supported by pipe . Often covered with white, polyethylene film and used to over-winter nursery stock.

11. The design of a greenhouse depends upon the latitude of the place and the requirement of crop. ATTACHED GREENHOUSES Lean-to- half greenhouse split along the peak of the roof. Useful where space is limited Least expensive, availability of water and electricity Advantages Disadvantages Temperature control is difficult Location of windows and doors on the supporting structure must be kept in mind 24

12. Ridge and Furrow Greenhouse Consist of many even-span structures placed one after another forming a range of greenhouses. The side wall is eliminated between the green Structure serves as furrow or gutter to carry rain and melted snow away.

13. Saw tooth type Greenhouses There is provision for natural ventilation Specific natural ventilation flow path develops in a saw tooth type greenhouse This design is used in areas under high

14. Based on Utility: Greenhouses for active heating. Greenhouses for active cooling.

15. Greenhouses for active heating. During the night time, air temperature inside greenhouse decreases. To avoid the cold bite to plants due to freezing, some amount of heat has to be supplied. The requirements for heating greenhouse depend on the rate at which the heat is lost to the outside environment. Various methods are adopted to reduce the heat losses, viz., Using double layer polyethylene, thermo pane glasses or to use heating systems, such as unit heaters, central heat, radiant heat and solar heating system.

16. Greenhouses for active cooling. During summer season, it is desirable to reduce the temperatures of greenhouse than the ambient temperatures, for effective crop growth. This type of greenhouse either consists of evaporative cooling pad with fan or fog cooling. This greenhouse is designed in such a way that it permits a roof opening of 40% and in some cases nearly 100%.

17. Fan and Pad Cooling System

18. Based on Construction: Wooden framed structure. Truss framed structure Pipe framed structure.

19. Wooden framed structure In general, for the greenhouses with span less than 6 m, only wooden framed structures are used. Side posts and columns are constructed of wood. Timber locally available, with good strength, durability and machinability also can be used for the construction Pipe framed Structure Pipes are used for construction of greenhouses, when the clear span is around 12m. In general, the side posts, columns, cross ties and purlins are constructed using pipes. In this type, the trusses are not used.

20. Types of protected structure Wooden framed structure Truss framed structure Pipe framed structure

21. Truss framed structure If the greenhouse span is greater than or equal to 15m, truss frames are used. Flat steel, tubular steel or angular iron is welded together to form a truss. Most of the glass houses are of truss frame type, as these frames are best suited for pre-fabrication.

22. Based on number of Span Free standing or single span Multi-span or gutter connected

23. Based on Environmental control: Naturally ventilation Passive ventilation

24. Based on Covering/Cladding material: Glass glazing. Fiber glass reinforced plastic (FRP) glazing Plastic film UV stabilized LDPE film. Net house. .

25. Glass glazing. Glass as covering material has the advantage of greater interior light intensity. These greenhouses have higher air infiltration rate which leads to lower interior humidity and better disease prevention. Plastic film Flexible plastic films including polyethylene, polyester and polyvinyl chloride are used as covering material in this type of greenhouses. They are cheap and cost of heating is less when compared to glass greenhouses. The main disadvantage with plastic films is its short life.

26. Plastic Film Net house LDPE Film

27. FRP Polyvinyl chloride rigid panels, fibre glass-reinforced plastic, acrylic and polycarbonate rigid panels are employed as the covering material in the quonset type frames or ridge and furrow type frame. This material is more resistant to breakage and the light intensity is uniform throughout the greenhouse when compared to glass or plastic. The main disadvantage is that these panels tend to collect dust as well as to harbor algae, which results in darkening of the panels and subsequent reduction in the light transmission. There is significant danger of fire hazard.

28. Based on Cost of Construction: High cost Green House Medium cost Green House Low cost Green House

29. Low cost Green House Constructed with locally available materials such as bamboo, timber etc . The UV film is used as cladding materials no specific control device for regulating environmental Parameter Light intensity can be reduced by incorporating shading materials like nets. The temperature can be reduced during summer by opening the side walls Such structure is used as rain shelter for crop cultivation. This type of greenhouse is mainly suitable for cold climatic zone

30. Medium cost Green House semiautomatic control arrangement with minimum investment. Constructed using galvanized iron pipes Exhaust fans with thermostat are provided to control the temperature. Evaporative cooling pads and misting arrangements are also made to maintain a favourable humidity

31. As these system are semi-automatic, hence, require a lot of attention and care, and it is very difficult and cumbersome to maintain uniform environment These greenhouses are suitable for dry and composite climatic zones.

32. High cost Green House Temperature, humidity and light are automatically controlled. These are indicated through sensors or signal receivers. For example, temperature control system consists of temperature sensor, heating/cooling mechanism and thermostat-operated fan.

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