Roller Shutters or Thermal Curtains: What to Choose to Insulate
For pure insulation, the roller shutter is the most effective solution: fitted outside, it stops solar radiation before it reaches the glass and creates an insulating air gap, while providing blackout and security. But it requires building work, a budget, sometimes co-ownership approval, and remains impossible when renting. The thermal curtain is the interior alternative, with no works and reversible.
The Kurtens 3-in-1 curtain, 620 gsm, holds back up to 7 °C of difference* and blocks 100% of light, hung on a simple rod. It is the best solution when a shutter is not an option, or a decorative complement where a shutter already exists.
Why the roller shutter insulates best
The roller shutter acts outside, upstream of the window. It stops solar radiation before it heats the glazing in summer, and creates a sealed air gap between the shutter and the window that limits losses in winter. PVC models with insulated slats are the most efficient. It also adds total blackout and a real security gain.
Its constraints are heavy. Installation means building work and a significant budget, often co-ownership approval, and it modifies the facade. The motorised mechanism needs maintenance. Above all, the shutter is out of reach when renting, where the structure cannot be touched.
Comparison table: roller shutter or thermal curtain
The shutter acts outside, the curtain inside. Here is the honest comparison.
| Criterion | Roller shutter | Kurtens thermal curtain |
|---|---|---|
| Thermal efficiency | Very high (exterior) | High, up to 7 °C difference* |
| Security | Yes | No |
| Building work | Yes, fitting and facade | None, on a rod |
| Renting | No | Yes |
| Reversible | No | Yes |
| Decor and acoustic | Low | Yes, dresses and dampens noise |
*Data obtained under optimal test conditions. Effectiveness depends on exposure, glazing and fitting.
The thermal curtain: the no-works interior alternative
The thermal curtain does not stop the sun before the glass like an exterior shutter, but it intercepts the radiation at the window, on the inside, and limits losses in winter. The Kurtens curtain, 620 gsm and three layers, holds back up to 7 °C of difference* and blocks 100% of light. Its advantage over the shutter is elsewhere: it hangs on a rod, with no works or drilling, stays fully reversible, dresses the window and dampens noise. Discover the custom thermal curtains collection.
For the full anti-heat strategy, see our guide on how to cool a room without air conditioning. ADEME confirms that protecting your openings from the sun is the most effective summer measure, in its summer comfort guide.
Summer in practice: block the sun during the hot hours
The summer reflex is the same in both cases: cut the sun during the hottest hours, then ventilate at night when the outside air drops. With a shutter, you close or tilt it during the day to stop the radiation before the glass. Without a shutter, the thermal curtain drawn at the same hours takes over on the inside, intercepts the radiation at the window and keeps the room cooler, then opens in the evening to enjoy the cool air. In both cases, effectiveness depends on the discipline of the gesture: close early and keep closed while the sun beats down.
When the shutter, when the curtain, when both
The roller shutter is the answer when you own the home, can undertake works and want maximum insulation, total blackout and security. The thermal curtain is the answer when a shutter is impossible, when renting or in a restrictive co-ownership, when you want to avoid works, or a reversible, decorative and acoustic solution. On a window already fitted with a shutter, the curtain comes as a complement: it improves thermal comfort on the inside, dresses the room and dampens noise.
To compare with replacing the window itself, see also thermal curtains vs double glazing.
How much does each solution cost
The roller shutter represents an investment per window, fitting included, plus any motorisation and the maintenance of the mechanism. It is a durable but costly solution, and not recoverable when moving house. The made-to-measure thermal curtain costs the price of a curtain, fitted yourself, and moves freely. For a controlled budget, a rental, or a window that already has a shutter, it is the most accessible solution.
The Kurtens thermal curtain
The Kurtens 3-in-1 curtain insulates the window without touching the structure. It combines three technical layers, weighs 620 gsm, holds back up to 7 °C of difference* and blocks 100% of light, while dampening noise. Cut to measure to the exact dimensions of the window, it avoids leaks on the sides, hangs on a rod with no drilling, and stays reversible. It works in summer against the heat and in winter against the cold. Configure yours in the custom thermal curtains collection.
Frequently asked questions
Does a thermal curtain insulate as well as a roller shutter?
No, not in absolute terms. The roller shutter acts outside and stops radiation before the glass, which makes it more effective. The thermal curtain acts on the inside and holds back up to 7 °C of difference*. Its advantage is elsewhere: no works, reversible, decorative, and possible when renting.
Which solution to insulate without being able to fit a shutter?
The thermal curtain is the best interior alternative when a roller shutter is impossible, when renting or in a co-ownership. Hung on a rod, with no works, it limits losses in winter and blocks solar radiation in summer, while dressing the window.
Can I add a thermal curtain on top of a roller shutter?
Yes, it is even a good combination. The shutter blocks heat and cold outside, the curtain adds a barrier on the inside, dresses the room and dampens noise. The two complement each other without getting in the way.
Does a thermal curtain work in summer and winter?
Yes. A dense thermal curtain blocks solar radiation in summer and limits heat loss in winter. The Kurtens 3-in-1 curtain, at 620 gsm, works both ways, which makes it useful all year round.
Does the curtain provide the security of a shutter?
No. Security against break-ins is an advantage specific to the roller shutter, which the curtain does not provide. If security is your priority, the shutter remains essential; the curtain plays on thermal comfort, blackout and decor.
Does made-to-measure improve the curtain's insulation?
Yes. A curtain that is too narrow or too short lets air leak on the sides and at the bottom. Cut to measure to the exact dimensions of the window, the curtain covers the whole opening and removes those thermal bridges, which clearly improves real insulation.
Key takeaways
The roller shutter is the most insulating solution, because it acts outside, but it requires works, a budget and remains impossible when renting. The thermal curtain is the no-works interior alternative: reversible, decorative, acoustic, it holds back up to 7 °C of difference* and works in summer and winter. When a shutter is impossible, or as a complement to an existing shutter, it is the most flexible and accessible solution. The Kurtens 3-in-1 curtain, 620 gsm, is cut to your exact dimensions. Configure yours in the custom thermal curtains collection.
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