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Close your curtains to keep warm (and reduce bills)

Posted by Cathy Debenham on 11 January 2010 at 1:21 pm

Walking home from a friend's house last night I was surprised to see how many people hadn't closed their curtains, despite sub zero temperatures.

Hanging curtains, and closing them at dusk, can make a significant difference to the warmth of your house, and to how much you spend on heating. Research on heat loss through traditional sash windows carried out by English Heritage found that heavy curtains reduced the heat loss by 41% (and lowered the u-value from 4.3 to 2.5).

This isn't only the case for single glazed windows. Our front door is double glazed, and mostly glass. We keep the doors into the hall tightly shut, as there's a marked drop in temperature as you go past the front door. A solid door, with a good u-value is at the top of my wishlist of home improvements. In the meantime, maybe we should rig up a blanket.

Would it help, I wonder, if we could see the heat escaping out of the windows. I know that some community groups, like Bovey Climate Action and Cambridge Carbon Footprint, have invested in infra red cameras to show people pictures of where the heat is seeping out of their home. I'd be fascinated to have an infra-red photo of our house - I think it would bring it all into a clearer perspective.

While I was gawping in all these curtain-less windows, it also struck me how many houses had empty rooms with all the lights on ... but maybe that's another blog!

More information:

Energy saving and renewable energy guides.


If you have a question about anything in the above blog, please ask it in the comments section below.

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3 comments - read them below or add one

Cathy Debenham

Cathy DebenhamComment left on: 21 January 2010 at 2:57 pm

The aim is to keep any cooling air from the window behind the curtain. So you want curtains that fall at least to the level of the window sill. However, as you point out, it's not a good idea to have them covering the radiator, as all your hot air will then be trapped. 

I don't know if there's a rule of thumb. Some of ours sit on the window sill, others fall below it by a couple of centimetres. Both seems to keep the cold air out effectively. Personally, I'd prefer to take curtains up, rather than tuck them behind, but that's based on aesthetics. Any suggestions about which is better for energy efficiency are welcome.

The other thing that makes a difference is the thickness of your curtains. Heavy curtains are more effective at keeping you warmer. And there are some technical fabrics available which claim to keep the heat in / cold out. I haven't tried them, so can't vouch for their effectiveness.

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dtandersonComment left on: 21 January 2010 at 12:48 pm

What is the best height for curtains to maximise heat efficiency and reduce loss? What other recommendations are there? Our house has radiators under the windows, as normal. However, curtains that cover the radiator means that heat rises behind the curtains and heats the windows principally.

Should the curtains finish just above the radiator, or longer and tucked in behind the radiator? This last option is less aesthetic and my wife would probably not choose this. However, heating bills are ever-increasing and I need to find the best solution.

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HeatandEnergy.OrgComment left on: 16 January 2010 at 5:04 pm

Also of interest - Air Tighness Testing in existing homes, A survey of dwellings has revealed that remedial works following air tightness testing have yielded energy savings of between 15% and  30%, this can sometimes be achieved for as little as a couple of pounds and a little attention to detail. more......

This may be of interest We have limited funds available for purchase of solid wall insulation in some local authorities. See here

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