A guide to getting the most out of your thermal lined curtains
- Kerrin Auld
- Consultant
In short
Thermal lined curtains keep your home warmer by slowing the heat loss that happens at cold windows, known as the reverse chimney effect. To get the most from them, make sure the curtains fit snugly with no gaps top or bottom, choose a separate thermal lining (and an interlining in really cold areas) rather than relying on coated fabric alone, and close them before dark to trap the warmth already in the room.
Table of contents
How is heat actually lost through windows?
You know the old saying that hot air rises? Well, during cold weather that is exactly what happens, and something called the reverse chimney effect comes into play.
It is widely accepted that cold air is denser, and therefore heavier, than warm air. When it’s cold outside the air close to the window is cooled and sinks down (due to its density increasing with the temperature change). When the cooled air sinks it’s replaced by warmer air from other parts of the room.
As you can imagine, this then creates a circulating current, taking all of your warm air and replacing it with cool air. And just like that, you have lost most of your heat, not just near the window, but in the entire room. There’s more on this in our guide to reducing heat loss through windows.
How do curtains help?
Well in some cases, curtains can actually make the situation a whole lot worse. If your curtains are not fitted correctly they form a channel between the window and the curtain, creating a space for the cooled air to sit and increasing the effect of the reverse chimney.
The most important aspect to note is that it is the power of each factor combined, which decreases heat loss. No single factor works in isolation.
Step one
The first thing to ensure is that your curtains fit your windows correctly. This means that they are within a millimetre of perfect, with absolutely no gaps at the top or bottom. They need to fit against the wall snugly, creating a seal between the curtain and window.
Step two
Once you have checked that your curtains fit correctly, or got some new ones made to measure by Russells, then it’s time to think about thermal lining options.
There are two options when it comes to thermal fabric. Either, you can have a curtain that is made from a thermal coated fabric, or you can have a separate thermal lining, which sits behind the regular curtain.
Thermal coated curtains are better than nothing, but having a separate thermal lining provides a whole new level of protection.
With thermal lining, a warm air pocket is created between the lining and curtain, providing additional protection from the reverse chimney effect.
You can even go one step further to increase the insulation level by having an interlining such a bumph put in between the curtain fabric at the front and the thermal lining at the back. It simply creates another warm air pocket and is great in really cold parts of the country.
Step three
Once you have your curtains fitted, make sure that you close them before it gets dark. This allows you to utilise the warm air that is already trapped inside your house.
For thermal options that work right across your home, you can also pair curtains with thermal blinds and curtains. To get the right fit and lining for your windows, book a free in-home consultation.
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Choosing the right curtains for your home
Not sure which curtains will suit your home? Find out everything you need to know with this free guide.
Frequently asked questions
Can thermal lining be added to curtains I already own?
In many cases, yes. A separate thermal lining can often be made up and fitted behind existing curtains, giving them much of the warmth of purpose-made thermal curtains. One of our consultants can check whether your current curtains and heading style suit a retro-fitted lining.
Is a separate thermal lining better than thermal coated fabric?
A separate thermal lining gives a whole new level of protection compared with a thermal coated curtain alone, because it forms an extra insulating air pocket. Coated fabric is better than nothing, but a dedicated lining performs best.
Why do my curtains need to fit so snugly?
If curtains have gaps at the top or bottom, or don’t sit close to the wall, they create a channel where cooled air collects and the reverse chimney effect worsens. Curtains that fit within a millimetre of perfect form a seal that keeps the warmth in.
What is an interlining and do I need one?
An interlining, such as bumph, sits between the front fabric and the thermal lining to create a second warm air pocket for even more insulation. It’s especially worthwhile in really cold parts of the country, and your local consultant can advise whether it suits your home.
When should I close my thermal curtains?
Close them before it gets dark. Drawing the curtains while the room is still warm traps the heat already inside your home, so you hold on to it through the cold evening rather than letting it escape through the window.
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