Solar Film or Heat-Blocking Curtains: What to Choose Against Heat
Solar film and heat-blocking curtains both block solar radiation, but they are not managed the same way: film sticks to the glass and stays permanent, darkening the window all year and never coming off, while a curtain is drawn or opened at will, day and night, and moves freely. The film acts at the glass, the curtain acts at the window and can be modulated.
The Kurtens 3-in-1 curtain, 620 gsm, holds back up to 7 °C of difference* by intercepting the radiation, with no building work and no professional fitting. Reversible and useful in winter against the cold too, it adapts where film, being irreversible, forces a permanent compromise on light.
What solar film does, and its constraints
Solar film is a thin layer applied to the glazing that reflects part of the radiation. Manufacturers claim up to 90% of solar heat rejected depending on the model, by blocking infrared before it heats the room. It is an effective, discreet solution that takes up no space.
Its constraints are structural. Film is permanent: once applied, it darkens or tints the window continuously, summer and winter, when in winter you actually want to capture the sun's heat. It is irreversible without scraping. On double glazing, an interior fit beyond roughly 1.2 m² risks thermal shock to the pane, which often requires an exterior fit by a professional. Finally, the quality of the fitting strongly determines the result.
Comparison table: solar film or heat-blocking curtains
Both intercept heat, but on opposite logics: permanent at the glass versus adjustable at the window.
| Criterion | Solar film | Kurtens heat-blocking curtain |
|---|---|---|
| Heat blocking | High, at the glass | High, up to 7 °C difference* |
| Day / night control | No, permanent | Yes, open and close |
| Useful in winter | No, darkens all year | Yes, also insulates from cold |
| Reversible | No, stuck on the glass | Yes, on a rod |
| Fitting | Pro recommended (large panes) | None, do it yourself |
| Risk to the glazing | Thermal shock possible (double glazing) | None |
*Data obtained under optimal test conditions. Effectiveness depends on exposure, glazing and fitting.
The curtain's decisive advantage: day-and-night control
This is the fundamental difference. Film forces a permanent compromise: it darkens the window continuously, including on grey days and all winter, when you would rather enjoy the light and the sun's free heat. The curtain modulates: closed during the hot hours to block radiation, open the rest of the time to keep the view and the brightness.
This control is also seasonal. A dense thermal curtain blocks heat in summer and limits losses in winter, whereas film stays calibrated to reject the sun all year. For the full anti-heat strategy, see our guide on how to cool a room without air conditioning.
How much does each solution cost
Solar film is sold by the square metre of glazing, with the addition, for large panes or an exterior fit, of a professional's labour. It is a one-off cost, but the fitting determines the result and the film is redone after a few years.
A made-to-measure heat-blocking curtain costs the price of a curtain, fitted yourself on a rod, with no labour. It lasts for years, can be moved, and also plays a decorative and thermal role in winter. For a rented home or a controlled budget, it is the most flexible solution. Discover the custom thermal curtains collection.
When film wins, when the curtain wins
Film makes sense when you want an invisible solution that takes up no space, on a window you never wish to dress, and the permanent darkening does not bother you. The curtain wins as soon as you want to keep control of the light, enjoy the sun in winter, a reversible solution with no works, when renting, or a year-round thermal benefit. The two can even be combined on a very exposed window.
To specifically protect your furniture and flooring from UV fading, a topic distinct from heat, see our guide on anti-UV curtains. And for a large exposed glazed surface, see stopping heat through a large window.
The Kurtens heat-blocking curtain
The Kurtens 3-in-1 curtain is designed to block heat at the window. It combines three technical layers, weighs 620 gsm, holds back up to 7 °C of difference* and blocks 100% of light. Cut to measure to the exact dimensions of the window, it avoids heat leaks on the sides, hangs on a simple rod with no works, and stays reversible. It works in summer against the heat and in winter against the cold, where film stays fixed on a single use. Configure yours in the custom thermal curtains collection.
Frequently asked questions
Is a heat-blocking curtain as effective as solar film?
Both block solar radiation, the film at the glass, the curtain at the window. A dense 620 gsm thermal curtain holds back up to 7 °C of difference*. The real difference is not so much raw efficiency as control: the curtain modulates day and night and also serves in winter, the film stays permanent.
Is solar film a problem in winter?
That is its main limit. The film stays stuck all year and keeps rejecting the sun in winter, just when you want to capture the free heat and light. The curtain, being adjustable, opens in winter to enjoy the sun and closes in summer to block it.
Can I fit solar film myself?
On a small single-glazed pane, yes. On double glazing beyond roughly 1.2 m², an interior fit risks thermal shock to the pane, and an exterior fit by a professional is often recommended. The curtain, by contrast, hangs on a rod with no constraint.
Solar film or curtain for a rental?
The curtain suits renting better: reversible, hung on a rod, it can be removed and reinstalled elsewhere without changing anything. Film is stuck on the glass and is not recoverable, which makes it of little use when you are not the owner.
Can solar film and a curtain be combined?
Yes, on a very exposed window the film rejects part of the heat at the glass and the curtain adds an adjustable barrier on the inside. But for most homes, the thermal curtain alone is enough and keeps the advantage of control and winter use.
Does a heat-blocking curtain work in winter too?
Yes. A dense thermal curtain limits heat loss through the window in winter, on top of blocking solar radiation in summer. The Kurtens 3-in-1 curtain works both ways, where film stays calibrated to reject the sun all year.
Key takeaways
Solar film and heat-blocking curtains both block heat, but film is permanent, irreversible and fixed on a single use, while the curtain modulates day and night, also serves in winter and is fitted with no works. Film suits those who want an invisible solution and never to dress their window, the curtain those who want control of the light, reversibility and a year-round thermal benefit. The Kurtens 3-in-1 curtain, 620 gsm and up to 7 °C of difference*, is cut to your exact dimensions. Configure yours in the custom thermal curtains collection.
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