Thermal blackout curtain vs. simple blackout curtain: a comparison
A simple blackout curtain blocks light. A thermal blackout curtain blocks light and also works against cold and noise. On the shelf, the two look alike, but their construction has nothing in common: an opaque coating on a light fabric on one side, a dense multi-layer assembly on the other. The Kurtens 3-in-1 curtain (620 g/m², 3 layers) shows a temperature difference of up to 7 °C*, measured in the laboratory between the window pane and the room.
This guide compares the two types of curtains on concrete criteria: thermal performance, blackout, sound insulation, price and durability. The goal is to help you invest in the right product for your actual needs.
What is the difference between a thermal blackout curtain and a simple blackout curtain?
The difference is not in the ability to block light (both block 95 to 100%). It lies in the construction of the fabric and the performance it makes possible:
- Simple blackout curtain: a standard fabric (polyester, thick cotton) covered with an opaque coating (often a white or black acrylic coating on the back). The coating blocks the light. The fabric has no particular insulating properties. Typical density: 150 to 300 g/m².
- Thermal blackout curtain: a technical multi-layer assembly (dense decorative fabric + high-density fleece + insulating/blackout membrane). Each layer has a function: the fabric absorbs, the fleece insulates, the membrane blocks light and radiation. The Kurtens 3-in-1 curtain weighs 620 g/m².
The difference in weight is telling: a simple blackout curtain of 150x230 cm weighs 500 g to 1 kg. A Kurtens thermal blackout curtain of the same size weighs about 2.1 kg. This extra mass is what creates the thermal and acoustic barrier.
Detailed comparison table
| Criterion | Simple blackout | Multi-layer thermal blackout |
|---|---|---|
| Blackout | 80-100% (variable, often overstated) | 100%* (multi-layer structure, no coating) |
| Thermal gain | Rarely measured | Up to 7 °C* (laboratory measurement) |
| Sound attenuation | Rarely stated | Up to 22 dB* |
| Density | Variable, often not stated | 620 g/m² (Kurtens 3-in-1) |
| Construction | 1-2 layers + opaque coating | 3+ technical layers (fabric + fleece + membrane) |
| Blackout durability | The coating cracks within 2-4 years (washing, UV) | Structural, does not degrade with washing |
| Made to measure | Rarely (standard sizes) | Yes (to the nearest cm at Kurtens) |
| Price | 15-60 € | 80-350 € |
| Lifespan | 2-5 years (fragile coating) | 10-15 years |
Thermal performance: the gap that changes everything
Between a light coated fabric and a dense multi-layer curtain, the difference does not show only on a spec sheet. You feel it in front of the window:
- With a simple blackout curtain: the fabric blocks the light, but its construction is not designed for the cold. The feeling of a cold surface in front of the window remains.
- With a multi-layer thermal blackout curtain: the feeling of a "wall of cold" in front of the window disappears. The temperature in the room is more even. The heating works less. The estimated saving is 25 to 120 euros per year depending on the glazing and the heating system (source: calculations based on ADEME data, 10-15% of heat loss through windows).
In summer, the gap is just as significant. A simple blackout curtain blocks light but lets through 80 to 90% of solar heat (the thin fabric heats up and releases the heat into the room). A thermal blackout curtain blocks light AND 60 to 80% of solar heat thanks to its mass and insulating layers.
Blackout: why coatings age badly
Low-cost simple blackout curtains use an opaque coating applied to the back of the fabric to block light. This technique has a durability problem:
- Cracking: after 10 to 20 washes, the coating starts to crack. Tiny holes appear and let light through. Blackout gradually drops from 100% to 90%, then 80%.
- Peeling: the coating comes away from the base fabric, creating uneven areas that let light through in places.
- Odor: some acrylic coatings give off a chemical smell, especially in summer when the curtain heats up in the sun.
A multi-layer thermal blackout curtain does not rely on a surface coating. Its blackout comes from the very structure of the fabric : the internal membrane blocks light mechanically, not chemically. It does not crack, does not peel and does not lose performance wash after wash. This is structural blackout, not a surface treatment.
Acoustic performance: the invisible bonus
A coated simple blackout curtain is thin and light: it is not designed to reduce noise, and its acoustic performance is rarely stated.
The 620 g/m² Kurtens thermal blackout curtain reduces noise by up to 22 dB*: the brand states this value under test conditions; the effect you notice at home depends on the noise, the other paths sound takes and the installation. This is the difference between a curtain that blocks light and a curtain that also works against cold and noise.
For a bedroom facing a busy street, this triple performance is decisive. A single curtain solves three problems instead of stacking a blackout + a thermal + an acoustic curtain (more expensive, bulkier, less effective than an integrated multi-layer). To learn more about acoustics, read our article soundproof curtains: do they really work?
When is a simple blackout curtain enough?
A simple blackout curtain remains a good choice in specific situations:
- Rarely used guest room: if the room is only occupied a few nights a month, investing in a thermal blackout curtain is not justified. A 30-euro simple blackout curtain does the job for darkness.
- Room already well insulated, with shutters: if you have shutters that you close every evening and efficient double glazing, the curtain only needs to block the remaining light (the glow around the shutters). A simple blackout curtain is enough.
- Very tight budget, temporary solution: a 20-euro simple blackout curtain will do for one summer or one winter before you invest in a durable technical curtain.
When is a thermal blackout curtain essential?
- Main bedroom (daily use): you sleep in this room 365 nights a year. Thermal insulation (stable all night), blackout (deep sleep) and acoustics (fewer awakenings) affect your health every day. The investment is fully justified.
- Baby's room: infants are sensitive to temperature (the WHO recommends 18-20 °C for babies' sleep), to light (10-20 lux is enough to wake them) and to noise (noise peaks = awakenings). A thermal blackout curtain addresses all three.
- Home without shutters: the curtain takes over the full role of the shutter (darkness + insulation). A simple blackout curtain does only half the job.
- Window exposed to cold (north, wind) or heat (south, west): the multi-layer curtain works on the feeling of a cold surface near the window and on comfort in the room.
- Street-facing bedroom: the stated attenuation of up to 22 dB* helps you get back to calmer sleep, where a simple blackout curtain is not designed to filter traffic noise.
The calculation over 10 years
| Criterion | Simple blackout (replaced) | Kurtens thermal blackout |
|---|---|---|
| Initial price | 30 € | 150 € (made-to-measure average) |
| Lifespan | 2-4 years (coating degrades) | 10-15 years |
| Cost over 10 years | 75-150 € (3-5 replacements) | 150 € (no replacement) |
| Heating savings over 10 years | 0-50 € (negligible thermal gain) | 250-1,200 € (25-120 €/year) |
| Balance over 10 years | Net cost: 25-150 € | Net benefit: 100-1,050 € |
Over 10 years, the thermal blackout curtain costs the same (or even less) than a simple blackout curtain that keeps being replaced, while generating 250 to 1,200 euros in heating savings. It is an investment, not an expense.
Discover our made-to-measure thermal blackout curtains : 620 g/m², 100%* structural blackout, temperature difference of up to 7 °C* measured in the laboratory, sound attenuation of up to 22 dB*. 14 colors, made to the dimensions of your window, free delivery in 2 to 3 weeks. To compare blackout levels, see our guide blackout vs light-filtering vs opaque. To choose the color, see the color guide.
*Data from tests carried out under optimal conditions.
Frequently asked questions
What is the difference between a blackout curtain and a thermal blackout curtain?
A simple blackout curtain blocks light with an opaque coating on a light fabric. It is not designed to insulate against cold or noise. A multi-layer thermal blackout curtain blocks light through its structure (no coating) and also works against cold and noise: the Kurtens 3-in-1 curtain shows a temperature difference of up to 7 °C* measured in the laboratory and a stated attenuation of up to 22 dB*. Three functions in one curtain instead of one.
Does a blackout curtain insulate against the cold?
A simple blackout curtain is not designed to insulate: it blocks light, not cold. To act on the feeling of cold, choose a multi-layer curtain whose performance is measured. Fabric weight alone is not enough to predict a result: the construction, how well the window is covered and the installation matter just as much.
Does the coating on a blackout curtain last?
The coating (opaque coating) on a low-end blackout curtain degrades within 2 to 4 years: cracks after 10-20 washes, peeling, gradual loss of blackout. Multi-layer thermal blackout curtains do not use a coating: the blackout comes from the structure of the fabric (internal membrane), which does not degrade with washing or UV exposure.
Is a thermal blackout curtain more expensive than a simple blackout curtain?
At purchase, yes: 80-350 euros versus 15-60 euros. Over 10 years, the cost reverses. A simple blackout curtain lasts 2-4 years (3-5 replacements = 75-150 euros). A thermal blackout curtain lasts 10-15 years (no replacement = 80-350 euros). Adding the heating savings (25-120 euros/year), the thermal blackout curtain generates a net benefit of 100 to 1,050 euros over 10 years.
Can I get a thermal blackout curtain in a light color?
Yes. The blackout of a technical multi-layer curtain does not depend on the color but on the internal structure (blocking membrane). A cream beige Kurtens curtain blocks exactly as much light (100%*) as a gray curtain. All 14 colors offer the same thermal, blackout and acoustic performance*. You choose the color on aesthetic grounds only.
Is a simple blackout curtain enough for a baby's room?
For darkness alone, a good 100% simple blackout curtain can be enough. But babies are also sensitive to temperature (the WHO recommends 18-20 °C) and to noise (noise peaks wake them up). A multi-layer thermal blackout curtain works on all three: total darkness (100%*), a temperature difference of up to 7 °C* measured in the laboratory and attenuation of up to 22 dB*. For daily use over several years, the investment is justified.
How can I tell a genuine thermal blackout curtain?
Check three criteria: the stated fabric weight, a detailed multi-layer construction (not just "blackout fabric"), and measured, quantified performance (°C, dB, % blackout). If the seller advertises "thermal blackout" without any data, it is probably a simple coated blackout curtain with a marketing label. Kurtens curtains state 620 g/m², up to 7 °C* and up to 22 dB*.
More curtain tips
Explore our latest articles
