Orientation and Structural Design
This domain tests how greenhouse orientation and frame design affect light, ventilation and crop load. Questions often ask you to choose an orientation or identify a structural weakness.
Orientation rules
- In tropical Maharashtra, a north–south ridge for single-span houses gives more uniform light across the day and reduces midday overheating on one side.
- In high-latitude winter production, east–west orientation can capture more low-angle winter light, but summer overheating and uneven light are penalties.
- Align the ridge perpendicular to the prevailing hot summer wind where possible, and use side and ridge vents for cross-flow.
Structural design checks
- Gutter height of 4–6 m improves air volume and reduces temperature build-up.
- Roof slope around 25–30° sheds rain and condensation.
- Design for wind load, crop load (including fruit and trellis), and hanging equipment.
- Use galvanised steel, protected joints and adequate foundations; insect screens add wind load.
Worked example
A 1,000 m² single-span house is planned with a 6 m span, 3 m gutter and ridge running east–west. Reasoning: 3 m gutter is low for tomato in a hot climate; east–west gives uneven summer light. Better choice: north–south ridge, 4.5 m gutter, 8 m span if structure allows, and ridge vents. The crop load of trellised tomato plus wind screens must be included in the truss design.
Traps that cost marks
- Copying a cold-climate orientation without adjusting for tropical summer.
- Specifying a low gutter to save cost, then fighting heat and poor airflow.
- Ignoring wind load from insect netting.
- Designing for the crop at planting but not at full fruit load.