I can see that window shrink-film is effective for excluding draughts, but if you already have a 100% draught-proof windows, is it worth buying for the thermal insulation it provides over the course of one season?
TIA
Al
Actually it is not meant to stop draughts. In severe gales the film can balloon into the room.
Will it save more than it costs? It costs about =A36 to do a large set of windows. For breakeven you would have to be able to save about 55 kWhr of electricity or 150 kWhr of gas. It probably does save that over the course of an entire winter.
Does it make a difference to comfort? Most definately, and it is for this reason that DG takeup was so heavy in the UK despite payback over a century. The actual monetary saving of DG is actually quite small - and calculations assume no curtains or lined curtains or thermal lined curtains. Comfort wise it will eliminate the "cold plunge" off the glass which is very pronounced with large areas of single glazing. The air gap is typically quite large too - about 20-25mm, the earliest DG units were just 4mm glass / 6mm gap / 4mm glass.
A note is some film tape has changed, it is extremely tacky, has a weak film substrate, and bonds ridiculously strongly to paint such that a chisel blade AND solvent AND sandpaper have to be used to get the damn stuff off. I know this because I did it this afternoon for a relative! Normally it just pulls old paint off or shears off new paint due to a strong film substrate, but not this stuff - it was terrible leaving an evo-stik-come-superglue residue. The old double sided tape was much better.
I was fitting DIYplas.co.uk 3mm Cast Acrylic with PVC soft edging & nylon-cam-with-screws. Very easy to fit, easy to remove & remove any moisture buildup. Costs about =A320-60 depending on the size of the windows. Looks much better than film. Payback will be poor, but comfort is noticeably and vastly cheaper than fitting double glazing whose payback due to other insulation in place despite large glazed area would be well over 140 years.
The most economic solution is probably the film on a picture-frame screwed to the window which is easily removed for removing any residual moisture ingress without destroying the film. It is not true that moisture ingress rots window frames, they were most likely rotten already re putty lifted off the glass outside. I recall windows puddle wet & mouldy for weeks on end and it just wiped up every year, paint is a good barrier oddly enough.
Thermal linings work - as do curtains, so do not ignore the easy things first. I will not use film again, instead using the rigid stuff with a simple PVC soft edging. Remove after winter. You can pick up reasonably priced wood double & triple glazing somewhere in Scotland, DIY fit remembering the insulated cavity closures with DPC, except the FENSA gold-plated crowd want a fee.
Looks like a very useful supplier for all sorts of plastic sheet and fittings, I take it you recommend them?
Its the air that provides most of the insulation.
If the gap is around 20 mm as it is in double glazing it will be about as effective. If the gap is too big the air will circulate in the gap and the insulation will be close to zero.
If there are draughts that remove the layer of still air in the gap the insulation will be close to zero.
You can get sealed glazing with an extra layer of similar plastic to make them into triple glazed units. They have about twice the insulating value as normal double glazing when they have two 20 mm gaps.
I have used them for one order as above.
Panels are not cut by the square inch. You pick a panel from a range of sizes (eg, 1200x1200) and specify a free cut to one size (eg, 967x1159). For a large 3 pane window I simply spanned the 3 panes with one sheet to no ill effect, as I did with film actually.
I purchased based on price. You can buy 2400x1200mm locally, online or Ebay, but most places charge for cutting and per cut. The nylon cam- pegs & screws and PVC U-channel can be bought elsewhere, but it is another postage cost.
The system is simple, which gives it a good chance of success.
I've used them before a couple of times for stuff, though not for some years.
Were fine.
I put a piece on the single pane over the front door in 1986, the sort you stick on with double-sided tape around the sides and then bring tought with a hair drier.
It's still there, and working fine. Sounds like a bass drum if you tap it.
Nylon cam with screws. What's that then?
With one secondary glazing system you cut the sheet slightly oversize (24mm), then apply a PVC U-channel around the outside which acts to seal against small surface defects. The sheet complete with U-channel perimeter is held against the window frame by use of screw fitted nylon cams around its perimeter.
The nylon cams consist of a cylinder with cam lobe at one end. The nylon cylinder "body" acts to retain the weight of the sheet, the cam lobe is turned to retain the sheet against the frame. o- is a graphic representation of the "o" cylinder and "-" cam which projects out from the end of the cylinder. You turn the cam to retain the sheet. A picture is worth a lot of words, go visit the site.
I would add today that very large sheets could benefit from being 4mm over 3mm acrylic - the extra stiffness might be necessary to prevent the sheet bowing. There is a distinct noise benefit, not unsurprisingly. Also useful for sheds & workshops where you want to avoid the windows running in water during winter yet do not want to spend much.
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