I have double-glazing in my 5-year-old house. In this very cold weather I wondered whether home-made shutters to fit inside the window openings (from inside the rooms) might reduce heat loss even more.
My tentative design would consist of 2" x1" framing with hardboard or plywood nailed to each side, forming a sandwich and the inner cavity copiously filled with, say, loft insulation material.
Each such panel would have a couple of handles affixed so as to quickly insert the panels once the sun goes down or remove them the next morning. The panels would be a snug fit inside the window openings, maybe with rubber draught excluder glued on to form a good seal.
The smaller windows are approximately 4' x 4' which would be the main ones to consider.
In northern Italy outside roller shutters were fairly common and seemed effective, but I found them a bit claustrophobic. I don't even like drawn curtains for the same reason.
No doubt your idea would work to some extent, because the same idea was popular pre-1950's, but with single glazing back then. Might heavy thermal curtains not work almost as well, if they completely filled the 'hole'?
Thermal curtains... Thermal curtains do increase the amount of condensation on single glazed (so do work), but are actually quite a disappointment because unless touching the floor they merely allow cold air to fall into the room just the same. Their thermal barrier is an open barn-door at the bottom.
Roller blinds... Roller blinds seem to outperform thermal curtains quite a bit due to a better seal to the frame and usually having a flat bar on the bottom which maintains some seal at the bottom. Heavy icing at -3oC is easily obtained.
Insulation-in-a-frame... Neither of the above have any chance of competing with even 25mm of rockwool which will grossly outperform them. If bothered about appearance, stick a "roller blind material" on the other side - it might need to handle condensation (severe icing in fact if single glazed).
Polystyrene slab was routinely used in commercial former factory buildings in London to reduce heat loss overnight through multiple extremely large steel frame single glazed (critall) windows. It was very effective although probably not fire retardant (F/R) - same goes for PIR foam, some insulation is F/R and some is not so check.
Single glazed wooden has a U of about 4.5, Double glazed uPVC is about
2.5, Double glazed uPVC argon filled is around 1.5 although doesn't stay argon filled for very long so a practical figure is U = 2.5. The U value of 50mm polystyrene is 0.5 if I recall so you reduce heat loss to 20% of the original value. That is a substantial saving hence "new build" have cell-like windows, no-bay-windows, and so on. Heat the rooms you use, set to frost-protection the rooms you do not. Wear a fleece and drop the temperature back a little BUT do not drop it too far because otherwise you battle to get it back up again. Duvets outperform blankets considerably.
I recently checked with a company which sells it, mostly for packing material. They used to sell plain or F/R at extra cost, but now they only sell F/R - which might suggest they are ONLY allowed to sell F/R no matter what purpose.
Umm a bit. We have internal shutters on the ground floor. They don't noticeably decrease heat loss. We also have internal shutters on windows in Italy. There, TBH, although looking pretty they are just an irritating PITA.
The English shutters are fixed to the window reveals the Italian ones are fixed to the windows and are thin, hinged wooden panels.
I don't like curtains either, let alone heavy ones, so they're out of the question. I must say, I am pleased by the generally positive responses - and contrary to Steve Firth's doubt as to the coldness of the weather, the fact is we all have to heat our surroundings and we are constantly urged to do so more efficiently.
I shall have to wait until I can put the car back out in the drive before the garage is free again to use as a workshop, so it may not happen this year (2010) until next winter. But I shall cost it up and compare materials. Not sure about polystyrene slab, as this stuff always seems quite flimsy when used as a packing material around televisions, DVD players and the like. A decent wooden frame as proposed should last for years (longer than me!) being constantly removed and replaced for three months of the year.
Hi Group In Finland the house where we stay has treble glazing with about one inch gap between the glass so there is merit in the idea of supplementary panels on the inside in the UK. It would be the old story of cost against convenience. Help I sound like a bean counter!
Do the sheds stock polyurethane board? Can't say I've ever seen it and I often peruse the stock even though I might not be buying anything that day. Where would you get it? Don't forget that hardboard is dirt cheap, as is the loft insulation.
My experience is with Victorian single glazed sash windows, where internal shutters do make a big difference. Whether the same difference would be felt with modern double glazed windows is debatable.
A single brick wall is a bit better than single glazing, but worse than double glazing.
Now if its cavity insulated brickwork, its a different story..
Even triple glazing isn't a patch on well insulated walls..
so those triple lined curtains, really DO make a helluva difference.
As to shutters, Id say a real difference as well.
The key being whether or not there is enough air movement at their edges to stop convection currents past the windows. If well sealed on rubber strip, probably getting on for 'full insulated wall' if slatted, almost completely useless.
the mechanism of heat transfer makes it clear. With an open cavity that is sealed..like a double glazed panel that is gas filled, or a window recess with a shutter, the transfer mechanism is convection off the warm inner panel, up to the top of the cavity, and down the cold outer panel. There is also some direct radiation through the glass of the window. But I suspect that's very low.
That's why filling cavities with fluffy stuff works: it slows air movement down to nothing, stalling convection currents, and making direct transfer through te air the only way to transfer heat. Air is a good insulator.
It also gibes a key to what makes a good shutter., At the least it must trap the air behind it. It is also beneficial if - since it cant totally fill the gap to the window and stop circulation, - it is itself insulated. Or possible has some way to restrict airflow built in.
At the very least, you will improve window U values by the thermal resistance of the shutter. In practice it may be a lot more. Convection calculations are not my strong subject.
In pure heatloss terms, windows are a trade off between significant solar gains by direct radiation from a high temperature sun, or effective high temperature sky, and loss from a low temperature room, by conduction and convection.
In any case, after dark, they make no gains and are pure loss. Curtains, or shutters, with as thick linings as you can afford, should always be drawn or closed at dusk..
Okay. Now, should the shutters be pushed into the aperture right up tight against the window frame or should they best be inserted into the first 3 inches of the aperture? That is (in the latter example), an air gap of some 4 inches would exist between the window and the shutter.
Point taken. With our house, because we only have drafty old windows, closing the shutters at dusk makes a noticeable difference, but I'm not sure that the occupants of a modern, double glazed house would notice the same difference. Probably not, although I'm sure shutters would help, but to a lesser degree.
Funny thing is, with all the talk of shutters, single/double/triple glazing, various forms of heat and controls, whatever the theory, it is what the occupants feel or perceive that is important.
That is true. I've just come in from a few hours' shopping in Spalding and it's snowing again. Even though the temperature in the kitchen has dropped to around 56 deg (Fahrenheit) while I've been out, it feels as warm as toast compared to outside.
CurtainsMadeSimple gurgled happily, sounding much like they were saying:
You'd be surprised. There's a signwritten van around this area belonging to a bloke who seems to specialise in wooden internal shutters, and from outside they can look very good indeed. I've not had a close-up look at 'em from inside, but the pics on his website look good.
Isn't everything?
Ever heard of hinges?
I think you might be a _tidge_ biased, given your posting name & email address, though...
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