Greenhouse Shading Systems: A Comprehensive Comparison and Usage Guide for External vs. Internal Shading
In facility agriculture, a well-designed shading system effectively regulates light and temperature within greenhouses, improving crop growth conditions. The two primary solutions are external shading and internal shading. This guide provides a detailed comparison of their advantages, limitations, and practical selection criteria to help you choose the best system for your climate and crop needs.
1. Shading System Comparison
| Feature | External Shading | Internal Shading |
|---|---|---|
| Installation | Outside the greenhouse (roof or eave) | Inside, below the roof structure |
| Cooling Effect | Best – Blocks ~90% of heat before entry | Moderate – Heat already enters the space |
| Insulation | Lower – Less heat retention | Higher – Traps some indoor warmth |
| Light Uniformity | Potential light spots (direct blocking) | Diffused, softer light distribution |
| Installation Cost | Higher – Must withstand weather | Lower – Protected environment |
| Maintenance | More demanding – Exposed to elements | Easier – Indoor access |
| Lifespan | 5–8 years (depends on material/climate) | 8–12 years (less wear) |
2. When to Choose External Shading?
✔ Hot climates/summer seasons (tropical/subtropical zones) – Prevents up to 90% of solar heat gain.
✔ Large-scale greenhouses – Reduces cooling loads (fans, pads) and energy costs.
✔ UV protection – Extends the lifespan of glazing (glass, polycarbonate, film).
Installation Tips:
- Drive system: Use waterproof, dust-resistant electric tracks or chain drives.
- Reinforced supports: Design for local wind/snow loads; secure roof attachments.
- Smart controls: Integrate with environmental systems for auto-adjustment.
3. When to Choose Internal Shading?
✔ Temperate/cold regions – Balances shading with heat retention in winter.
✔ Small greenhouses/research facilities – Easier to install and adjust.
✔ Light-sensitive crops (e.g., ornamentals, herbs) – Provides gentle, diffused light.
Installation Tips:
- Track layout: Align with roof structure to avoid wrinkling.
- Fabric selection: Opt for adjustable (30–90% shading) or reflective white screens.
- Operation: Manual for small setups; automated for large/commercial greenhouses.
4. Hybrid Solutions for Flexibility
For multi-season or multi-crop greenhouses:
- Summer: Prioritize external shading to minimize heat buildup.
- Spring/Autumn/Night: Use internal shading for insulation and light diffusion.
- Smart integration: Centralized control systems optimize energy efficiency.
Conclusion
External shading excels in heat rejection, while internal shading offers precise light and thermal management. The optimal choice depends on climate, crop type, greenhouse size, and budget. A hybrid approach may deliver the best balance. By selecting the right system, growers can achieve higher yields, lower energy costs, and superior crop quality.
