Outdoor Shading Fabrics: Openness Factor, gtot and How to Read EN 14501
How to choose solar screen fabric — openness factor, total solar factor gtot, colour and EN 14501 comfort classes — for glare, heat, privacy and view retention.
Short answer: two numbers decide most fabric choices. Openness factor governs view, airflow and daytime privacy. gtot governs heat.
Openness factor: what it controls
| Openness | View out | Privacy | Glare control | Typical use |
|---|---|---|---|---|
| <1% | Minimal | Highest | Highest | Bedrooms |
| 1–3% | Restricted | High | High | West-facing |
| 3–5% | Good | Moderate | Good | General-purpose |
| 5–10% | Very good | Lower | Moderate | View-priority |
Colour: the counter-intuitive part
- Light colours reflect more solar radiation but scatter light.
- Dark colours absorb radiation but give better view clarity.
gtot and EN 14501
gtot (total solar factor) — the fraction of solar energy that passes into the room through the fabric and the glazing together.
Mesh versus opaque
| Mesh / solar screen | Opaque PVC-coated | |
|---|---|---|
| Rain closure | No | Yes |
| View out | Yes | None |
| Airflow | Yes | None |
What to ask any supplier
- "What is the openness factor and gtot?"
- "Is the fabric two-tone?"
- "Mesh or opaque?"
- "What is the fabric warranty?"
- "What is the cleaning regime?"
- "Is the retention bead welded or extruded?"
Written by the engineering team at GRAND HOMEDECOR (Guangdong Grand Homedecor Technology Co., Ltd.).
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