Thermal Curtains and Roman Blinds: Using Lining and Interlining to minimise draught and reduce heat loss

Posted by on Nov 7, 2009 in Curtains, Tips & Techniques | No Comments

After resisting for as long as possible, the time has now come for us to switch our heating system timers on again  – because let’s face it, it’s suddenly become quite chilly over the last few weeks. Our thoughts instantly turn to how we can save money over the winter months whilst keeping our houses cosy in the mornings and evenings. Well here are a couple of hard facts to start off with:

Heat loss is mainly caused by badly insulated walls and windows: 80% of household heat is said to be lost through windows and from the thermo imaging picture below it’s easy to see why.

Thermo Imaging showing heat loss through windows
Thermo Imaging showing heat loss through windows

But if you have a fairly old house boasting single cavity walls and single glazed windows there is still much you can do to minimise heat loss and keep your energy bills down.

By “thermal” we mean the constituent parts of the curtain or blind (face fabric, interlining and lining) combine to create an insulating layer between the heat in your room and your window.

For your curtains:

  • Choose a medium to heavy weight interlining – as this thick cotton/ wool material that is sandwiched between the front (face) fabric of your curtains and the lining fabric at the back of your curtains will act as the first barrier to your escaping heat and will add both warmth and luxury to your curtains.
  • Choose a thermal or blackout lining fabric – you’ve got two options here. Thermal lining fabric has a thin, rubberised backing to it and is therefore effective at reducing heat loss. Blackout lining has an additional acrylic layer to prevent light passing through the fabric.

For your blinds:

  • the same principles basically apply. Our roman blinds are fabricated with light weight interlining as standard – as heavier weights of interlining tend to restrict the operation of the blind. However this interlining, combined with a blackout lining will still be extremely effective at reducing draught from your windows and minimising heat loss – particularly where your blind fits neatly into a recess.

Should I choose thermal or blackout lining? Well, the additional acrylic layer makes blackout lining even more effective at minimising heat loss, so we’d always recommend blackout lining over thermal. In the winter it will maximise the thermal effect of your curtains and in the summer will prevent bright light from beaming through the curtains and diluting their colours and patterns – which will also help to protect them from the damaging effect of the sun’s rays.

Are there any downsides to thermal/ blackout lining? Not really. Whilst the additional coating gives the lining fabric a little more stiffness, this doesn’t really translate through to the finished curtains – and actually makes them feel a little more substantial/ opulent. Also, in the summer months, well interlined, blackout curtains will keep your room cooler when the curtains are shut, and, which is a great advantage for bedrooms  –  darker in the evenings. However thermal and blackout linings do cost more than standard sateen linings, and will typically add 5 to 10% to the price of your curtains or blinds.

How effective are thermal curtains and blinds? Statistics abound on how much you will save on your heating bills by thermally insulating your curtains and blinds. We were struck last winter at how much warmer our sitting room was in the evening when the curtains were closed, so we decided to put the theory to the test.

We carried out a simple test on some standard sitting room curtains that had a fairly thick cotton face fabric, medium weight interlining and standard cotton sateen lining. After the heating had been on for a couple of hours the temperature in the centre of the room was 23 degrees. However even without thermal /blackout lining, the temperature behind the curtains (which covered a door into the garden) was 17 degrees – which we thought was a pretty good indicator as to how effective the curtains were at reducing heat loss!

In our next blog on energy saving we will be giving more tips on minimising heat loss – from curtain light lock to issues concerning the location of your radiators.