Insulating value of blinds rather than curtains?

Yes well off topic. Feeling a bit under the weather and pondering future improvements. The living space here is a big open plan area with empty windows - no blinds or curtains and no rails have ever been fitted. It's pretty well insulated but when it's really cold, as it was this weekend, the heating system isn't quite keeping things as warm as it should. But having taken a proper look at the windows, I don't think the designer ever thought about curtains because most of the windows are butted up close to corners or beams or other things that would get in the way. And one slopes at the top!

So I'm wondering about blinds instead but am unsure whether that would have the necessary insulating effect. I'm no expert but always thought curtains worked because air got trapped in the folds. I've never had blinds in a house, except where there were curtains over the top of them. Thoughts? TIA

There are lots of different types of blinds with a wide range of prices. Have a chat with a local curtaining shop as they usually have a good knowledge of range and prices.

For your information:

Vertical blinds have virtually no insulative effect.
Venetian blinds are almost as ineffective as verticals in terms of retaining warmth but are very good for controlling sunlight.

Some of the modern styles of roller blinds are manufactured with thermal blocking qualities and look look a lot smarter than the old style spring loaded ones.

Roman blinds are available in a variety of price ranges with custom made ones being more upmarket, best quality and can be made to fit just to the extent of the window (liner) 'frame'.

Austrian blinds are the top end and although very decorative the gathered fabric will insulate as well as curtains would.

I have pondered this a bit, and came up with a Roman blind that is essentially, a thin quilt: two layers each of a tightly woven fabric, to minimise air flow, and a thin padding between these, of dacron or similar batting, that is enough to push the layers apart when hanging loose, to maximise the insulation, but thin enough that when raised/folded, the blind can fold out of the way. If made snug fitting to the sides of the windows, this would be fairly good insulation.

When things were still tight financially, we bought one blind, made especially for our bedroom window. It's a thermally-insulating roller type and it made a huge difference to our sleeping temperature in that room. It's still one of the best purchases we ever made for the house, in terms of its effect on our comfort. Otherwise we have no curtains and except for one or two nights in a year, we're warm enough with the fire.

we have put thermal backed roller blinds on all the range sliders in the dinning/kitchen/lounge..have been impressed with them.. they do keep in the warmth..also, because they roll right up out of the way, they let in a lot more light ( and sun warmth ) than the curtains that tended to block about 1/3 of the window even when drawn aside.
an expensive purchase, but well worth it

If you are handy you can make roman blinds quite easily (even I've done it [:0]) and use the thermal backed fabric.

One other option that has come to mind is a pleated blind such as Verasol which have a metallic finish to reflect heat or Duette which are a double zig-zag with air cells between for insulation. These are fairly expensive though and be aware that they can tend to generate a cold damp zone between the blind and the window (as many blinds or curtains can) which fosters mildew on the blind and these blinds are pretty much uncleanable without destroying the pleating and construction of the blind.

A note of caution on using thermal backed fabrics is that the coating on such fabric usually off-gasses fumes which can be pretty noxious. This is worst when new and in situations where there are a lot of windows in an enclosed room. Worth considering the health implications in a bedroom situation [xx(]
My ex used to make curtains and we had to air out the workroom if thermal fabric had been there overnight before it was able to be worked in.

www.consumer.org.nz/articles/curtains

Makes interesting reading - curtains not as effective as we are lead to believe, the most important thing appears to be stopping the hot air near the celing from falling down the gap between the curtain rail and the wall at the top.
Roman blinds, or a close pelmet?

Megan, thats a really interesting article as people are buying thermal curtains which are really expensive and not necessarily getting much from them.
I was going to say that the ceiling fan makes a massive difference to heat in the room and, although I dont have one, friends do and it makes the room feel incredibly warm compared with when its turned off

The best insulation from curtains or blinds will be from ones that create a layer of still air behind the blind/curtain, and even better, another layer within the blind/curtain.
The thinner the layer of still air, the less convection will occur if it is just air with no filler. If there is a filler, to stop convection, such as foam, batting etc, then the thicker the layer the more insulation.

(As mentioned in that article,so called "thermal" curtains, are often less effective than tightly woven fabrics. This is because tightly woven fabrics tend to be heavier, and therefore hold more trapped air within them. "Thermal" fabrics stop air moving through the curtain but that isn't as significant unless there are serious draughts.)

So a Roman blind is the easiest to fit snugly, hard against the window reveal at the top and very closely sized to fit inside the reveal. This will reduce air movement around the top, sides and bottom, thus creating a layer of still air, that is not too deep, so convection within that space is slowed by friction. If the blind is quilted, it creates another layer within the blind, and the filler slows movement, as does the use of a tightly woven fabric.

The blind should fit close to the window, not on the face of the wall, but within the reveal but not be in contact with the window glass or frame, so it won't be in contact with any condensation, which would encourage mould on the blind. You will also need to wipe up condensation regularly to reduce the amount of moisture in the air by the blind.

The Duette blinds are better than a single layer, but because they are open at the ends, the air moves through them fairly easily, so the cells are less effective than a quilted blind.
The reflective blinds are best when used to reflect sun out the window to keep a room cool. They have some effect on air circulation, but not as much as tighter fitted, thicker blinds.

In the UK it is usual rather than having thermal curtains (which I hate because you can't wash them) but to add a liner which is hooked to the curtain, so can be removed separately and does not pick up the colour from the curtains when washed, if your curtains fade and you want to replace them, you can re-use the liners.
You can get very narrow curtain rails we have some here as there are built in pelmets which we did not dare get rid of in case it caused major damage.

If your window has a sloping top, just run the rail horizontally, yes you will have a gap at the top, but a much better effect than trying to make curtains at an angle. I have a window in the conservatory that I need to re-do the rail for the same reason.

Buying rolls of material from trademe is a lot cheaper than spotlight. I got I think 30 metres for around $150

Actually, diverting again, there is a thing called an 'Ecofan' which sits on the top of a woodburner and once it heats up, it moves the hot air from the top of the stove out across the room making the whole room warm

We need curtains on our kitchen ranch slider. It's double glazed, so not such an issue with either heat loss or condensation, but we only have a sun filter there at present but that will allow marauding gaupers to look in on us after dark. We'd probably go for a non backed curtain which will pull out of the space more easily.

We have been using an Ecofan for two winters now, and I suspect that it has been doing a great job.

Lots of useful info here thanks guys. Looks like thermal blinds might be the way to go. I'll have to investigate prices and see if I can put them on the list for next winter.