🧭 Greenhouse Planning

A greenhouse can fail even before construction starts if the wrong site, orientation, or covering material is chosen. Good greenhouse planning reduces operating problems later, especially poor light use, waterlogging, high wind damage, and difficult movement of labor and materials.

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Why Planning Matters

The purpose of greenhouse planning is to create a structure that admits sufficient light, supports crop growth, resists local weather, and can be operated economically over many years.

Planning decisions affect:

1. crop productivity
2. construction cost
3. operating cost
4. labor efficiency
5. durability of the structure

Greenhouse planning is a long-term technical and economic decision, not just a construction decision.

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Site Selection

A greenhouse site should be selected so that it supports both crop growth and easy operation.

Important site-selection points are:

• level or nearly level land to reduce grading cost
• good solar exposure
• proper drainage
• good air movement
• access to water, power, labor, and transport
• protection from damaging wind where possible

Trees or buildings should not cast heavy shadows on the structure. Where windbreaks are needed, they should protect the house without reducing useful light.

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Orientation of the Greenhouse

Orientation determines how efficiently the structure receives sunlight and how it responds to prevailing winds.

The ideal orientation depends on:

• latitude
• season of use
• type of crop
• greenhouse width and design
• local wind direction

In practice, orientation is chosen to balance good light interception with ventilation and practical site layout.

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Structural Planning

Structural planning decides the shape, span, height, and frame arrangement of the greenhouse.

The structure should:

• resist local wind and other loads
• minimize unnecessary shadow from structural members
• provide adequate working height
• suit the type of crop to be grown

For example:

• hoop or arch structures are common for low-cost polyhouses
• straight side-wall structures are better where tall crops or internal benches are needed
• gothic forms can improve side height while retaining structural strength

The final structure must suit both crop biology and engineering safety.

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Choosing Covering Materials

Covering material strongly influences light transmission, heat conservation, durability, and cost.

Important selection criteria are:

Criterion	Why it matters
Light transmission	Determines photosynthetic energy available to the crop
Weight	Affects structural design and handling
Impact resistance	Matters under hail, strong wind, or rough handling
Outdoor durability	Determines service life
Thermal behavior	Influences heat retention or overheating
Cost	Controls investment feasibility

Typical service-life ranges are:

Covering material	Approximate service life
Glass and acrylic sheet	About 20 years
Polycarbonate and FRP sheet	About 5-12 years
Ordinary polyethylene	Very short life, often only a season
UV-stabilized polyethylene	About 2-3 years

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What an Ideal Covering Material Should Do

An ideal covering material should:

1. transmit visible light needed for photosynthesis
2. limit unwanted radiation that causes overheating
3. remain durable under outdoor exposure
4. keep cost within economic limits
5. provide useful life long enough to justify investment

In cool regions, higher thermal retention becomes more important. In hot regions, ventilation and heat-load management become more critical.

Summary Cheat Sheet

Planning element	Main concern
Site selection	Level land, drainage, solar exposure, access, wind safety
Orientation	Better light interception and workable ventilation behavior
Structural planning	Strength, usable space, reduced shading, crop suitability
Covering material	Light transmission, durability, thermal behavior, cost
Ideal outcome	High crop performance with manageable construction and operating cost

References

1 source • [1]

[1]

AENG252 Protected Cultivation and Post-Harvest Technology notes