Thermally lined curtains and Roman blinds

Tim Robbins

Not sure if this is right forum

On new extension we got triple glazed windows but they are still not as good as wall. So going to get thermally lined curtains on some windows and thermally lined Roman blinds on others. Costs a bit.wondering has anyone any advice or experience?

MicktheMan

I'm wondering what are you expecting from these curtains? What does thermally lined actually mean?

What is your tg window u-value?

Tim Robbins

Very good u value for a window. Somewhere between 1.0 and 1.5 I think.

Problem is a good window is way off a good wall which is 0.18

SharkMX

Im going to go with the laws of physics and say your "thermally" lined curtains will have no effect on anything but your wallet.

Tim Robbins

But why? Any sort of curtain will usually help with a window, surely thermally lined a little more?

SharkMX

https://www.boards.ie/discussion/comment/121394515#Comment_121394515

If you have new triple glazed widows you shouldnt have any draughts at them. Sometimes curtains help with draughts. How much are these curtains and how do you you think they are going to help?

Im sticking with my first post and going to say the only effect they will have compared to normal curtains or blinds is that your wallet will be much lighter.

Jonathan

https://www.boards.ie/discussion/2058323530/thermally-lined-curtains-and-roman-blinds

Are you talking about condensation in the morning? If so you need to either ventilate the room or invest in a dehumidifier.

See this video for a good explainer.

https://www.youtube.com/watch?v=TIDb-pdOnXM

Deeec

I would be very disappointed if I built an extension and needed thermally lined blinds. A modern extension built to high building standards should be warm and not need curtains at all for warmth. Are you really sure you need this?

Being honest I've never heard of thermally lined blinds - I would be concerned that you are paying extra for something that's the same as a normal curtain or blind.

graememk

I've heard of thermal blinds, but for a triple glazed there wouldn't be much benefit in them.

Much more benefit if it was an older double glazed or single glazed window.

slave1

rear of my 70's semi is N facing, put in passive standard triple glazed a few years back, the difference was unreal re heat retention, took all blinds/curtains off the wall as no need and not overlooked. You should not need anything other than good windows

I do have cassette blinds in the front room which offer benefit of heat retention but that's because I do not like direct sunlight on TV etc

Tim Robbins

Thanks for comments.

The U Value for a triple glazed window is between 1.0 and 1.4. They are good. But no way near as good as a wall with some good insulation.

Meaning if you have four / five windows in a big room it doesn't you have a surface area that is nowhere near as good as your wall which is 0.18. I can see a temperature difference with a heat measurement. The window tends to be about 1 to 2 degree's colder than wall meaning you will get heat loss. This is with no curtains and with no blinds. I think paying 10 percent extra for thermal lining in blinds and curtains is a no brainer really.

MicktheMan

https://www.boards.ie/discussion/comment/121394500#Comment_121394500

Very good u-value for a tg window would be 0.8 w/m2K, between 1 & 1.5 w/m2K is average at best.

What you are likely noticing is the radiation effect of the 'relatively' cooler glazing surface compared to the wall surface. Any decent curtain will eliminate this effect. I'm with @SharkMX on this. Save your money, you don't need a "thermal" lined curtain, whatever that is!

Btw, had you gone for 0.8 w/m2K windows, you wouldn't need any curtains to be comfortable.

allinthehead

I got thermal lined black out curtains for a patio sliding door and they make a huge difference. But I got them to keep the heat from the sun out. I have a work station positioned near the door and at certain times of the day I would melt without them.

If they can keep the heat out would they also keep heat in?

graememk

https://www.boards.ie/discussion/comment/121397840#Comment_121397840

The heat in, is infrared heat. So you can block that coming in with the blinds, But heat lost is via conduction/convection

DC999

https://www.boards.ie/discussion/comment/121398039#Comment_121398039

I did not know that!!!

allinthehead

https://www.boards.ie/discussion/comment/121398039#Comment_121398039

I get ya, but would it not trap some heat in a similar fashion to say a duvet? They're pretty thick, like me🤣

mykrodot

I think people are becoming obsessed with airtight passive warm houses. Lets face it our Winters have become an awful lot milder. I am in 20 year old semi detached house tonight which I just bought, C3 rated, double glazed, no heating except a small stove and its way too warm!! Why are we becoming so obsessed with having absolute heat all the time, no cool spots, no air allowed in.

Climate change means we are all getting warmer weather, not colder. Yet everyone is obsessed with insulating their houses to the nenth degree!! Its not healthy. Maybe I am showing my age but years ago Autumn and Winter was far colder, frost and ice from October. We had fires, no insulation, lots of draughts and we all wore more clothes! Happy out.

Mellor

https://www.boards.ie/discussion/comment/121394511#Comment_121394511

They prevent heat transfer via radiation. Nothing about that breaks the laws of physics. It's just of limited benefit in OPs scenario

https://www.boards.ie/discussion/comment/121398039#Comment_121398039

This^^^

That is the better sue case for thermal curtains. To reduce heat gain. And they do that well in say an Australian climate. Not so much an issue in Ireland.

SharkMX

https://www.boards.ie/discussion/comment/121398287#Comment_121398287

The op was talking about heat going out. Very little of that is due to radiation.

Mellor

https://www.boards.ie/discussion/comment/121398919#Comment_121398919

Which is why in the second paragraph, I pointed out the better use case for them.

But to be really clear, they also have an R-value and that will reduce the heat lost via both conduction. The effect is marginal, but nothing about the suggestion breaks the laws of physics. I’m really not sure what you are getting at there.

SharkMX

https://www.boards.ie/discussion/comment/121398955#Comment_121398955

im not really sure why you are either tbh.

But sure lets leave it.

Flinty997

Have heavy lined (not thermal) curtains on some large windows older double glazed. But it's in an older house with drafts. Make a noticeable difference. Helps keep the heat out on very hot days. You notice it's cooler behind the curtain.

Also some black out blinds and blackout curtains in some bedrooms. Also makes a minor difference.

With triple glazing in a modern setting, can't imagine it's a hugh difference. Though hard surfaces tiles etc always feel colder vs carpet . I assume it's the same with glass versus fabric. Even when ambient temps are the same.

Tim Robbins

I am still not getting the physics here. if you have a lot of windows in a room and even if they are 0.8 u value that is still like a poor insulation standard compared to your wall which is around 0.18. So surely the curtain / blind helps the window to catch up.

MicktheMan

https://www.boards.ie/discussion/comment/121405060#Comment_121405060

The u value relates to the rate of energy flow through the element, be it a wall or window or whaterver, by conduction. But because the curtain is effectively hanging in mid air and is not part of the element, the u value of the element is not impacted. Therefore, the hanging curtain is not beneficial in reducing the conductive heat loss through the element, in this case the window.

Why 0.8 w/m2K?

Another significant form of heat transfer by windows is by way of radiation and is often misunderstood. Think of the window as a 'cold' sun shining on you when it is cold outside. Pulling the curtain is akin to pulling a cloud across this cold sun and therefore removing (blocking) the cold window radiation from your skin and instantly improves your comfort. Any decent curtain or blind will cause this positive effect. Also, it has been proven that if the overall window u value is 0.8 w/m2K or better, this radiation effect disappears.

Yellow_Fern

https://www.boards.ie/discussion/comment/121398264#Comment_121398264

I would not necessarily agree with you saying it is unhealthy but there is a mass delusion that is a good way to fight climate change.

Flinty997

We also had smog from all those fires.

I remember the bus conductors standing on door step with a torch trying to find the kerb for the driver. You could literally only see a few metres at times.

Tim Robbins

https://www.boards.ie/discussion/comment/121405369#Comment_121405369

Ok but the brick may have u-value 2.3, you put insulation in front of it and then you prevent or slow down heat loss.

Is it not the same thing? The best window is 0.8 which is not great, compared to a wall. Heat is more likely to go out through your windows than your wall. Especially if you have a few big ones. So blinds / curtains would be a good assistant?

MicktheMan

https://www.boards.ie/discussion/comment/121406131#Comment_121406131

Is it not the same thing?

No. You are confusing two different and separate heat loss mechanisms.

Is the insulation freely hanging in front of the block wall? It is not, it is FIXED to the block wall thus insulating it (if fixed properly).

Your curtain is HANGING in front of your window thus adding no insulation value whatsoever to the window.

Look, either take what I say or go and spend extra on something which will not benefit you but I'm done here explaining the science bit. Good luck!

Jellybaby_1

https://www.boards.ie/discussion/2058323530/thermally-lined-curtains-and-roman-blinds

My experience for what its worth, I recently bought 'thermal curtains' and I'm not terribly keen on them to be honest. The ones I got don't have a thermal FABRIC lining. They have something like a plasticy backing which seems to be glued to the actual curtain. I'm sorry I got these particular curtains because they just don't fall nicely, the sides stick out and I'll have to sew a couple of stitches to make them look right. I went back to the shop and the ones on display have a plastic thread holding the sides making them fall properly. I didn't notice that when I bought them. Maybe you're thinking of different type of thermal curtains though.

Tim Robbins

https://www.boards.ie/discussion/comment/121407144#Comment_121407144

Agree it doesn't add insulation to the window, but think it adds it to the room. Analogy is putting on a jacket may have a few air gaps at top and bottom but keeps you warming by slowing down the overall conduction / convention process. Science is about questioning - never stop.

Tim Robbins

https://www.boards.ie/discussion/comment/121407731#Comment_121407731

Curtains or roman blinds are up for consideration.

Thanks for you info.

SharkMX

https://www.boards.ie/discussion/comment/121410716#Comment_121410716

More importantly though science is about measuring. Try and work out how much heat you will be saving with your thermal curtains in cents and let us know.

Tim Robbins

https://www.boards.ie/discussion/comment/121411738#Comment_121411738

You can't get a u-value or any information about thermal characteristics for any blind or curtain other than it is thermally lined.

SharkMX

https://www.boards.ie/discussion/comment/121438237#Comment_121438237

Surprise, surprise :)