The cold is setting in: how an insulated roller shutter reduces heat loss through the window
When the first cold snap hits, your home reveals the truth
The first week has arrived when you turn the radiators back on, and after six months of high temperatures, your home reveals its true nature.
There’s the room that warms up in ten minutes and the one that never reaches the thermostat setting. There’s the lukewarm hallway and the bedroom that stays cold even with the valve turned all the way up. The instinctive reaction is always the same: turn up the boiler temperature.
It’s the most expensive solution that solves the least. In almost all cases, there’s no shortage of heat— it just escapes. And the place where it escapes most easily isn’t the wall. It’s the window, along with everything around it.
The window opening is the weakest point in the wall
An exterior wall is thick, multi-layered, and often insulated. A window opening is not. Within that space of just a few decimeters, the window frame, the roller shutter box, the side guides, and the shutter that slides inside it all coexist.
Each of these elements can serve as a vanishing point:
- A crawl space is a box recessed into the wall—often poorly insulated—that opens inward for inspection.
- The guides create a continuous channel from the outside to the inside, extending the full height of the window.
- The roller shutter curtain is the only surface that, at night, acts as a barrier between the glass and the cold outside air.
It is precisely on this last point that a game is being played that many people don't even realize they're playing.
What's Really Inside an Insulated Roller Shutter?
From the outside, an insulated roller shutter looks just like any other roller shutter: a slat made of aluminum or steel that winds onto a roller.
The difference is on the inside. Each bar is not just an empty shell: inside is eco-friendly polyurethane foam that is highly stable and long-lasting, requiring no maintenance.
Why it matters:
- A hollow profile allows heat to pass through the metal and through the air it contains, which moves freely.
- A foam-filled profile slows down that flow: the heat encounters insulating material instead of a vacuum.
There are two benefits, no matter the season: in winter, the heat you generate has a harder time escaping, and in summer, outside heat has a harder time getting in. The result is a room that reaches the temperature you set and maintains it longer, placing less strain on the heating and cooling system.
There’s also an effect you can’t see but can feel: the same material that slows the transfer of heat also dampens noise. A better-insulated room is almost always a quieter room as well.
How a Pracal insulated profile is made: Watch it in just a few seconds
It’s helpful to explain what’s inside a profile. Seeing it is another matter entirely. In this video, filmed at our plant in Polla, follow the four steps that transform a strip of aluminum into an insulating profile:
- The coil. The aluminum coil arrives pre-painted. We apply the paint in-house using a continuous process called coil coating: we are among the first in Europe to do so, and the color remains durable over time, resisting sun and weather.
- The shape. A series of rollers folds the strip step by step until it takes on the shape of the slat.
- Insulation. As the profile closes, the injection nozzle dispenses polyurethane foam, which expands and fills the entire cavity. The profile shown in the video is medium-density.
- The finished slat. Solid profiles emerge from the production line—free of air pockets—ready to become the roller shutter for your window.
Everything takes place on the same production line, without any external steps. For you, this means consistent quality, which we monitor from the first meter to the last.
Medium density and high density: the question almost no one asks
Here's the part that rarely shows up in estimates, but that actually makes all the difference.
Insulated profiles are not all the same: they vary in terms of the density of the internal foam. In the Pracal 2026 catalog, various models—in aluminum (L09, L14, L15, Ariel) and steel (C09, C12)—are available in both medium density (MD) and high density (HD).
Medium density
It's a well-balanced solution, suitable for most windows in a home. It has a slotted cap and fits standard widths well.
High density
This means more insulation material in the same available space inside the bar. There are three practical consequences, all of them tangible:
- Superior thermal performance. More insulating material means greater resistance to heat transfer, within the exact same footprint.
- Greater rigidity. The profile flexes less. This is why the high-density version can span wider openings (on some models, the maximum recommended width reaches 200 mm) and achieves higher wind load resistance ratings for the same width. It is also heavier: in strong winds, the fabric remains more stable in the guides.
- Superior long-term mechanical integrity. The high-density design uses a screw-on cap instead of a push-on cap: the bar remains firmly in place even after years of daily use.
The benefit is a roller shutter that provides better insulation and operates more smoothly. The advantage is that you only have to make this choice once: a properly sized shading system will last for decades, and the difference in initial cost is spread out over a very long period of time.
The question you should ask your installer is exactly this: “Is the profile you’re recommending medium- or high-density?” If the answer is vague, you’ve already gained some useful information.
ΔR: the number that measures how well a roller shutter insulates
At the end of the video, a symbol appears: ΔR ( Delta R). It's the technical term for how well a roller shutter helps a window retain heat.
ΔR is the additional thermal resistance that the roller shutter, when lowered, adds to that of the window frame. The air layer between the roller shutter and the glass, along with the material of the roller shutter itself, forms an additional barrier against the cold. The more effective that barrier is, the higher the ΔR. For the same model, a high-density profile, with more foam, has a higher ΔR than a medium-density one.
The rule to remember is simple: roller shutters with a higher ΔR value = less heat loss in the home. The profile material, foam density, and the system’s seal in the tracks and box all matter.
For this reason, in addition to density, you can also ask your installer for the ΔR value of the proposed profile. It’s a technical specification, not an adjective: it can be compared.
The sheet alone isn't enough: the system consists of four pieces
An excellent roller shutter mounted on the wrong tracks performs like a mediocre one. The window assembly works well only if all its components work together:
- The insulated profile, which serves as the primary thermal barrier.
- The guides with brushes seal the gap between the fabric and the guide. Without them, a continuous air gap remains between the fabric and the aluminum rail along the entire height of the window.
- The specialized gaskets, which ensure a tight seal where the trim meets the wall.
- The wind-resistant system, where conditions require it: a reinforcing bar and a wind guide keep the fabric securely in place even during gusts.
The benefit of thinking systematically is that you solve the problem completely, rather than just shifting it elsewhere. The advantage is that you do it in a single step, without having to return to the site over the course of three different winters.
Three checks you can do today, without any tools
You don't need a thermal camera to figure out if your window space is the problem. Five minutes is all it takes.
- The tissue test. Hold a light paper tissue close to the edge of the roller shutter box and then along the tracks, with the roller shutter lowered. If it moves, air is getting through.
- The test. Try moving the lowered curtain side to side. If it wobbles inside the track, the brushes are missing or worn out.
- The "ear test." With the roller shutter down, listen to the street noise. If it sounds as if the window were slightly ajar, the seal isn't tight: where sound gets through, air gets through too.
If even just one of the three tests fails, it’s a good idea to have the window covering system inspected before getting a quote for a new window. Often, the repair is quicker, neater, and much less invasive than you might think.
Dealing with the calendar
There is one final point to consider, and it’s simply a matter of common sense.
If you have work done on your window opening now, it will benefit you through March. The same work, if postponed until January, costs the same, but in the meantime, you’ve already paid two months’ worth of utility bills with a window that’s letting heat escape.
The benefit of taking action now is having your home ready for the real cold weather. The advantage is that the rest of the heating season will already be operating under the right conditions.
Winter is coming anyway. But whether to let it in is still up to you.
Pracal is practical.
Are you a professional? Configure medium- and high-density roller shutters, tracks, end caps, and accessories in a single workflow https://shop.pracal.com/
Product certifications can be requested at tecnico@pracal.com.
