What is solar shading?
Solar shading is the collective term for devices that block or reduce sunlight and solar heat, to prevent overheating, glare and reflections in a room. Shading can be fixed or movable, and fitted outside, between the panes or inside a window.
Outside works better than inside
Where the shading sits is the key difference:
- External shading stops solar heat before it passes through the glass. This is by far the most effective way to prevent overheating.
- Internal shading, such as curtains, roller blinds or venetian blinds, blocks light, but the heat is already inside. It helps against glare and for privacy, but far less against heat.
- Solar control glass lets less solar heat through. How well glass, or glass combined with shading, keeps out solar heat is expressed by the g-value (solar factor): the lower it is, the less heat gets in.
Types of external shading
- External screen blind: a fabric screen that runs down in side channels in front of the window. You can still see out.
- Awning: fabric that projects outwards, either at an angle over a window or horizontally over a terrace on folding arms.
- Roller shutter: slats that close completely. Also useful for security and insulation.
- External venetian blind: adjustable slats that let you control light and heat precisely.
- Fixed shading: an overhang, canopy, pergola or brise-soleil. Effective against high summer sun on a south facade, while still letting in low winter sun.
Tips for choosing
- Orientation: on the south (in the northern hemisphere) an overhang or horizontal shading works well. On east and west facades the sun is low, so vertical screens or blinds are more effective.
- Wind resistance: movable fabric shading must be retracted in strong winds. A wind sensor prevents damage.
- Control: motorised operation with sun and wind sensors ensures the shading also comes down when nobody is home.
- Consent: shading on the front of a listed building or in a conservation area may need permission. Check with your local authority.
- Combine with ventilation: night-time ventilation helps get rid of stored heat.
Related terms
- External screen blind
- Awning
- Roller shutter
- Brise-soleil
- G-value
- Overhang
- Canopy
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