how much heat would a curtain save?

Kernel_Sanders

retired2011 wrote: »

And as to putting a duvet over the windows :eek:!

Yes, I do have some extreme ideas; how about fixing bubble wrap over the entire window as soon as the heating season starts? You'll get a good level of insulation without blocking out the light

zeupater

rogerblack wrote: »

Quite little.
To put an absolute ceiling on the heatloss.
The area is around 8 square meters in total.
http://www.puravent.co.uk/AppendixA_UValues.pdf Page 23.
Let's say they are good ones, 2W/m^2/C.
This is 16W/C for all of the windows.

The average heating over the year will be about 10C.
10C*16W= 160W.

Neglecting stuff, assuming the curtains you have add nothing to the thermal effect, and the new ones double it - you may save 80W on average.
this is around 80 pounds a year, on normal rate electricity, or 30 pounds on gas.
It's probably really questionable that the decent curtains would pay off, especially as the existing ones presumably have some effect that I'm neglecting, as I can't find nice figures.

Hi

I'd look to include only the hours when the curtains are closed and the heating's on with the +10C benefit you raise ... so around 12Hrs/day of benefit for 4 months ....

... The annual saving would therefore be more like 230kWh (16W*10C*12Hrs*120Days) which is somewhere around £23 on daytime electricity or £8 on gas/E7 ....

As you say, these figures would reflect very good curtains replacing none .....

One other thing which needs to be considered by most when looking at lined thermal curtains is that a good proportion of houses have their radiators below windows in order to not take-up useable wall space .... if the curtains overhang the window sill and there is nothing to deflect the rising heat (shelf etc) then the curtains will likely provide the opposite effect to that being desired - ie, a warmer temperature behind the curtain and therefore increased heatloss ...

HTH
Z

zeupater

Kernel_Sanders wrote: »

Yes, I do have some extreme ideas; how about fixing bubble wrap over the entire window as soon as the heating season starts? You'll get a good level of insulation without blocking out the light

Hi

Going back to the early 70's a relative used to tape a wide format cling-film to the windowframe every autumn and then shrink it with a hairdryer so that it was really taught (almost drum-skin taught) in order to stop draughts and act as a thermal barrier, similar to double glazing. It seemed to work well and you didn't really notice it was there if there were no creases .... considering this, the bubblewrap idea doesn't seem all that extreme .... :D

Z

pob1976

Kernel_Sanders wrote: »

Yes, I do have some extreme ideas; how about fixing bubble wrap over the entire window as soon as the heating season starts? You'll get a good level of insulation without blocking out the light

Great idea, I had an idea, if you have non-lined curtains, do you think a survival blanket (can get from poundland) could be put between the curtains and stitch a lining on it? Cheaper than new curtains, I might try this and see if it works. Hope this helps anyone.

EricMears

zeupater wrote: »

One other thing which needs to be considered by most when looking at lined thermal curtains is that a good proportion of houses have their radiators below windows in order to not take-up useable wall space .... if the curtains overhang the window sill and there is nothing to deflect the rising heat (shelf etc) then the curtains will likely provide the opposite effect to that being desired - ie, a warmer temperature behind the curtain and therefore increased heatloss ...

You could of course tuck your curtains behind the radiator.

zeupater

EricMears wrote: »

You could of course tuck your curtains behind the radiator.

Hi

Funnily enough, when it was severely cold the winter before last we did roll up the bottom of a couple of curtains and ensure that they were on the window sill instead of overhanging ...

We're pretty lucky as most of our radiators aren't below windows and tbh we don't need to use the gch much, relying mostly on our log-burner as the main heatsource.

Our curtains in the main living parts of the house (ie the warmest) are all heavyweight and lined and I believe that they do make a difference ... however, I certainly wouldn't go out of my way to change curtains just for saving energy/money and would recommend that anyone should consider this in the long-term as part of normal redecoration ....

HTH
Z

Ben84

You can also buy old (ugly is best) curtains with good linings from charity shops and car boot sales very cheaply and transfer the lining to another pair of curtains you like or already own. I did this with some hideous gold curtains from the 70s that were huge and had good thermal linings. They only cost £2.

Kernel_Sanders

zeupater wrote: »

We're pretty lucky as most of our radiators aren't below windows

Actually it's an advantage to have radiators below windows because that helps even out the room temperature (that's the theory, anyway).

zeupater

Kernel_Sanders wrote: »

Actually it's an advantage to have radiators below windows because that helps even out the room temperature (that's the theory, anyway).

Hi

I can understand the theory in that it would be increasing comfort by directly warming the air being cooled by the glass surface and historical existance of draughts through and around windows and their frames. However, I would have thought that improvements in the insulative qualities of glazing would have almost negated the need for this and the overiding reason for having radiators below the window cill is simply that in most circumstances the area is 'dead wallspace' .... of the windows in our house, and most others that I can think of, there are very few windows with furniture against the wall directly below them ....

HTH
Z

Kernel_Sanders

A valid point Z, and unquestionable in older homes with modern windows but solid walls. However, double glazing, even with argon between the panes, is never going to insulate as effectively as a cavity filled with rockwool.
That said, I wonder how much closer triple glazing would take this? After the last couple of bad winters and with the government struggling to meet EU energy saving targets, I was expecting this to be the 'next big thing' but no, not a wimper! The Swedes must be laughing at us.