I had the same problem with my sash windows but hadn't done any sewing for years so I asked a friend. She showed me how to make roman blinds and the measuring was complicated so I had to make a test one before I felt confident. Then I was made redundant & found the time to make something a bit better, I experimented with magnets and space blanket & I now make serious thermal roman blinds, not quite for a living, but I make them at the bottom of the garden & can work around the school bus & looking after the house, chickens, etc.
I've just made my 100th blind & have an award for the Best Energy Saving Idea - I can't advertise on here it seems, so if you want the details them you'll have to PM me - I'm in Frome but send them all over the country.
what I did was to buy a set of cheap curtains from eBay while we faffed around choosing proper curtains and having them made up. then I free cycled the cheap curtains to a permanent home. Might that work for you?
I had a quick look yesterday - blimey, it's almost requiring us to get a second mortgage!
I came across the company blindinabox (or sthg like that) which got some dragon's den money (basically, they do cheap temporary blinds) - shame is: there maximum drop is only 198cm, while we need at least 250cm.
Will need to bite the bullet at some point though, and settle on something. I want to get the curtains right in term of insulation and look, and also need to get some blinds that let the light through while providing some insulation (for day time) - if Duette we must, I can't bear to think how much that will be...
According to research I've come across (I belong to a group which discusses this kind of thing ;) ) , thermal blinds are actually more efficient than curtains at keeping out cold, because you're trapping multiple layers of air and using that as insulation, rather than using the fabric itself as insulation. However, as MyLovelyMonster says, they become increasingly efficient if you incorporate little wooden flaps at the edges to stop air movement round the edges. The most efficient window coverings (not surprisingly!) are shutters with additional thermal insulation, followed by ordinary solid wooden shutters.
On the other hand, I don't think the research talked about exactly what their curtains were made out of, whether they had integrated thermal linings, etc. We have heavy wool curtains in one room and it made a big difference. On the other hand, the wool cost a fortune. I've seen blankets used as curtains look very good, and that might work out cheaper.
We will definetly look at curtains too in the medium term (i.e. before the winter) but will need to think about fabrics, railings etc in details. We are aiming for the blind as a first line of insulation...
To be honest if you have room for them curtains would provide you with far greater thermal insulation than blinds. The duette blinds are probably one of the better options but they are quite expensive.
We have just moved to a new flat with high ceiling. All very good looking, but bloody freezing already
The windows are single glazing "rotating" affairs, and all quite large. I will attempt the cling film student technique at some point, but I bet that will cost an arm and a leg considering the surface area of each panel.
We are looking at fitting thermal blinds in the short term, however: Are all thermal blinds 'blackout' blind as well? Can someone recommend a good affordable place to buy them?
I'll also try to do the silicone trick for all the crevices in the window frames - yet again, the size of them will make it tricky...