What blinds keep heat out?
Ranked by what actually works, and honest about which options only help with glare.
The short answer
The blind that keeps the most heat out is the one mounted outside the glass. Everything fitted on the inside is managing heat that has already entered the room.
Why position beats material
Sunlight through a window becomes heat when it strikes something solid. If that something is an internal blind, the blind warms up and radiates into the room. It is doing a good job on glare and a limited one on temperature.
Intercept the same sunlight before it reaches the glass and the heat never enters. That is the whole reason external shading exists, and it is why an awning outperforms a curtain by a distance that surprises people.
Ranked, most effective first
1. External shading — aluminium shutters, external venetians, ZipScreens
Stops the sun at the outside of the glass. Aluminium shutters and external venetians also let you keep airflow while shaded. ZipScreens close a patio in against sun and wind together.
2. Thermalite plantation shutters
The best internal option. Thermalite insulates two to three times better than timber or vinyl, and seals tight to the frame so heat is not moving around the edges. Louvres let you shade and ventilate at once.
3. Honeycomb blinds
Cellular construction traps a layer of air against the glass — the same idea as double glazing, and it works in both directions through the year.
4. Sunscreen roller blinds
Good on glare and UV, and they keep the view. Real but modest effect on temperature — choose these for comfort and fade protection rather than as a cooling measure.
Fit does as much as the product
An off-the-shelf blind leaves a gap at the edge of the opening. Warm air convects straight through it, and the rating printed on the fabric becomes largely theoretical.
Everything we make is measured to the opening, which is the unglamorous reason a custom product outperforms a cheaper one with better specifications on paper.
If the environmental side matters to you
Our roller blind fabrics are PVC-free, and include plant-based Ingeo cloths made from renewable resources rather than oil, across more than 3,000 colours.
Thermalite itself is made from non-toxic recycled material, with a paint finish that is hypoallergenic and sits below acceptable VOC emission levels — nothing gassing off into the room, which matters most in bedrooms and anywhere with poor ventilation.
On the commercial side we also supply SeaPlanet FR, a flame-retardant fabric made from recycled PET reclaimed from ocean beds. See Decor Commercial for that range.
Free in-home measure and quote
Brisbane and the Gold Coast. No obligation, and we do the measuring.