how much heat would a curtain save?

retired2011

I have 2, one at each end of a 24 ft by 12 ft long room, windows that are approx 8 feet wide and 5 feet high.

These are wooden framed and double glazed with 12mm between the glass panes.

There are no obvious draughts coming through them except for the trickle vent which can be shut.

At present there are just ordinary unlined curtains hanging there.

How much more heat would be retained if I was to hang full length thermal lined curtains on the 2 windows?

In other words if I spent £200 or more on thick thermal lined curtains would I ever get my money back?

My gas usage for heating, not including hot water and cooking is presently about 11,000 kWh, cost about £350 for the time it is on.

rogerblack

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.

Martyn1981

Hiya R2011, I think Roger is spot on, and you won't get your money back on energy savings, but you might well get your money back in comfort.

The heavy curtains will hopefully help to reduce the cold flow somewhat, making it easier on your heating system to reach and maintain comfort levels a little faster. Also I find that air flow is a major part of comfort - for instance in the winter I'm most comfortable when the living room is 19C, with doors and windows closed. But in Summer, I find less than 21C a little 'chilly' as the doors, windows and roof velux are open, creating airflow.

By sealing off you windows, or as I call our 4.5ft by 8ft living room glass 'negative radiators', you'll help to slow things down a little.

Wifey and mother-in-law made and fitted heavy curtains with thermal lining to the bottom of our loft stairs (after I converted the loft). They are very tightly fitted to the ceiling, and have weights in the bottom to ensure they sit tight to the floor too. I was going to get a sheet of Kingspan (perhaps 100mm) and simply make a removable door for the winter, but we decided on the suck it and see approach of curtains.

14 years on, and the curtains are still in use, I put them up when the heating gets switched on (Sept/Oct) and pack them away when it goes off (Mch/Apr), on hot days I simply pull them aside. I'm still shocked each year at the temp difference if I slide my arm behind the curtains.

Last years gas bill mid July 2011 to early July 2012 (51 weeks) was £350 (including all hot water and gas oven).

So you might not get your money back on your gas bill, but it might (just might) be profitable as a home improvement investment.

Mart.

Kernel_Sanders

You'd save much more by dividing this long room and only heating the part that you need. Also, £200 is a waste of money; buy a cheap 4.5 TOG king size* quilt from a supermarket and stitch it into the curtains. This will be far more effective!

*these are usually 220 x 225cm

Barneysmom

I've bought thick cutain lining for ours and it's a big improvement.
Also the curtains are lined velvet so there's a triple layer up.

The fabric of the curtains helps too, so if you get curtains with a raised fabric such as velvet, velour or chenille, the pile traps the warm air too.

Honestly, you wouldn't believe the difference a good thick pair of curtains makes.

These are the linings I've got

http://www.dunelm-mill.com/shop/thermal-curtain-linings-166202

I bought the velvet curtains from EBay new for £30 a pair, 90x90.

outtawork

I bought curtains at the bootfair & hooked them on the back of the original curtains, so stopped any draught in the winter, so far only done the bedroom curtains. The livingroom ones are 90x90 so it might be more expensive, but they don't have to look good or even match,just be the right size.

rogerblack

One thing to note.
If you make nice insulated curtain covers that succeed in equalling the insulation of the window - you may well get condensation on the window and the curtain cover surface next to it, unless the house is quite dry.

Barneysmom

Yeah, it's a strange one that, Rogerblack - since using the thick linings wed on't seem to get the condensation we used to?
I really can't think why though. Last year winter was rotten too.

rogerblack

Barneysmom wrote: »

Yeah, it's a strange one that, Rogerblack - since using the thick linings wed on't seem to get the condensation we used to?
I really can't think why though. Last year winter was rotten too.

It was a _hell_ of a lot colder last winter than this.
http://www.metoffice.gov.uk/climate/uk/anomacts/

Look specifically at the winter 2011/2012 anomaly with 1970-2000, for example.
2011 is all blues - a degree to two degrees colder than normal.
2012 is all pinks and reds - half a degree to a degree and a half warmer than normal.

That makes a lot of difference to condensation amounts.

bobhawke

Anyone got any recommendations for where to buy curtains?
I have single glazing, high ceilings and very big windows. Can't afford double glazing yet so in the mean time was looking at getting some curtains. Need 108".

retired2011

I didn't actually think that there would be any savings but 0.0064 pence a year, or whatever 160 watts of gas cost, is nothing to be sneezed at.

So my wife's suggestion that we will save a fortune on gas if she gets new thermal lined curtains for the lounge doesn't hold water.

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