Double Glazing or not?

[Just4Fun]

Around here the traditional type of double glazing is casement windows with the outer casement opening outwards and the inner casement opening inwards. Both casements are single glazed and together they form a double glazed unit when they sit in their own rebates in the jambs. Made from good quality pine theese windows normally last somewhere between 50 and 250 years if properly maintained all depending on how exposed the facade is to the weather.

That is the type of windows we have. The house was built in the 1890s. The windows are made of pine or similar soft wood and I have no reason to believe any of them have ever been replaced.

Have you any knowledge of upgrading these windows? I have toyed with the idea of making replacement (outer?) casements to house 2 glass panes instead of 1, but have not tried it.

 

[Just4Fun]

One pane had dimples and was sandwiched with the second pane with the tiny area between them a vacuum.

I once read about doors that incorporated vacuum panels, which were claimed to offer high insulation value. My concern (apart from cost) would be how long the panels would hold the vacuum.

 

[Jacob]

...Oil based paints were legislated out for the most part ages ago because of VOCs so unless there is something chemically different about the linseed oil paint I don't understand...

Linseed oil paints are very low on VOCs and it's one of the main selling points. It's not processed like Acrylic and other paints and involves no volatile solvents.
It is fairly expensive here but in use is amazingly economical and convenient. Also has indefinite shelf life (no solvents).

 

[KieranJW]

I wonder where I live if it would make sense to have inward opening windows and outward opening doors.

Tbh I was actually hoping to make the windows like a french window as when I lived there when my wife and i were younger i loved the fact that you could open the aperture completely I am also not against the idea of shutters but would possibly do them in the window reveals as more an extra thermal benefit in winter nights.
Will still do inward opening door though probably.

 

[KieranJW]

Around here the traditional type of double glazing is casement windows with the outer casement opening outwards and the inner casement opening inwards. Both casements are single glazed and together they form a double glazed unit when they sit in their own rebates in the jambs. Made from good quality pine theese windows normally last somewhere between 50 and 250 years if properly maintained all depending on how exposed the facade is to the weather. Made from oak they seem to last indefinitely.

I don't know thy Brits seem to believe that double glazing per definition must be made with those short lived sealed units.

Cool this sounds similar to something I was thinking with the secondary glazing.

 

[Jacob]

Tbh I was actually hoping to make the windows like a french window as when I lived there when my wife and i were younger i loved the fact that you could open the aperture completely I am also not against the idea of shutters but would possibly do them in the window reveals as more an extra thermal benefit in winter nights.
Will still do inward opening door though probably.

Internal shutters a big feature of georgian and victorian sash windows. They fold back into the reveals to look like panelling. Actually a brilliant solution and utterly superior to modern DG!

https://www.gshaydon.co.uk/blog/refurbishing-old-shutters
These are typical: The shutter leaves fold back in to the window reveal and look like panelling. The wrought iron bar is flat and hangs down behind when they are all folded back

 

[KieranJW]

Inward opening common in France - made possible by having tall narrow sashes which fold back into the window reveal and hence take up no space. They have outward openers too but as solid or slatted shutters un-glazed.

Haha sorry that's like my above reply. I had his in mind tbh just wasnt sure about shutters on the outside in terms of aesthetics. Hence the desire to do internal hidden in the reveals but this is just ideas at the minute.

 

[KieranJW]

I can comment on longevity sound and comfort. My windows were changed 45 years ago they are mostly aluminium thermal break units with 2 wood units.

1) Sound reduction is significant, I have a railway 30 metres from my back windows and after the IGU’s were fitted don’t notice a train going past, before a train stopped conversation.

2) longevity of IGU’s, currently at 45 years no noticeable change, will they ever (in my lifetime) need replacement? Only time will tell.

3) comfort, only an i*d*i*o*t would ever want single glazing. It’s not just the heat loss, though that makes a difference, it’s the fact that after installing IGUs there were no more cold floor level drafts during winter so the heating was turned down and it was more comfortable. Also never having condensation running down the inside of the windows.

Are IGUs a requirement for double/triple glazing? Absolutely not, as if you look at some countries you will find double and triple glazing using single sheets of glass, but you have to get the design right to allow moisture to escape and that isn’t usual or ever done in the U.K. as IGUs avoid all of that.

Thanks for the reply I think that's effectively what I'm trying to achieve to have a well designed window to remove my concerns of the double glazed units that can break down. I agree with he thermal problems with the single glazing but know I can make these well.

I really like the idea of double glazing by virtue of 2 casements effectively I would see this as not really different to secondary glazing with then the option to close shutters for further gains. I suppose really I like making things that last my virtue of good design and well executed joints and good standards of materials and workmanship.

 

[KieranJW]

Internal shutters a big feature of georgian and victorian sash windows. They fold back into the reveals to look like panelling. Actually a brilliant solution and utterly superior to modern DG!

https://www.gshaydon.co.uk/blog/refurbishing-old-shutters
These are typical: The shutter leaves fold back in to the window reveal and look like panelling. The wrought iron bar is flat and hangs down behind when they are all folded back

I agree about the shutters I really can't see why they are not still used.

 

[Jacob]

I agree about the shutters I really can't see why they are not still used.

Industry de-skilled.

 

[RobinBHM]

I get a bit on very cold days but have a condensation drip catcher in the cills

So condensation is a problem.

But not in terms of saving. Rule of thumb is that 20% of heat is lost through SG windows, halved if DG. 10% of your bill. For me about £100 p.a. DG would be a complete waste of money

that argument only works if the decision to replace is only based on thermal upgrade.

if somebody is replacing the windows anyway, there is virtually no difference in cost between single and double glazing…it’s pretty much irrelevant.

 

[Phil Pascoe]

But not in terms of saving. Rule of thumb is that 20% of heat is lost through SG windows, halved if DG. 10% of your bill. For me about £100 p.a. DG would be a complete waste of money

Yes. And if you calculate the annual energy cost difference between "C", "B", "A" and "A+" the difference is very small.

 

[Jacob]

So condensation is a problem.

No it is not a problem at all

that argument only works if the decision to replace is only based on thermal upgrade.

if somebody is replacing the windows anyway, there is virtually no difference in cost between single and double glazing…it’s pretty much irrelevant.

Until you come to replacing failed units, then later replacing failed plastic frames.

 

[Phil Pascoe]

Secondary glazing makes some difference but the air gaps between the panes are not thermally efficient. 16mm in air or 12mm in argon with super warm space bars is about as good as you can get.

I think your figures may be out of date - my new windows have argon filled 4mm - 20mm - 4mm panels, which I was told is the optimum gap.

 

[sometimewoodworker]

I really like the idea of double glazing by virtue of 2 casements effectively I would see this as not really different to secondary glazing with then the option to close shutters for further gains. I suppose really I like making things that last my virtue of good design and well executed joints and good standards of materials and workmanship.

My opinion on that system is that it’s far more complex than is needed. If you research the design requirements for good non sealed units you have almost the complete benefits of IGUs while using 2 panes and can easily use different thicknesses to help with sound control and you only need a single casement. If you want to add on shutters you can sill do that.

 

[Droogs]

I agree about the shutters I really can't see why they are not still used.

standard Edinburgh window in old stock builds is single pane sash with internal raised panel shutters. Most of those that have been replaced with DGU still retain the internal shutter as they are expected to be there in older houses. We kept ours when we fitted DG and they are used on very cold nights to keep the heat in. Our shutters are either original (1850's) or at most inter-war replacements as they are old slow growth Scots pine. The density certainly makes a difference. The DG has made a massive difference to quality of life in the flat, no more frost or fractal ice leafs on the inside of the window, calm and quiet (don't even hear the beep of the bin lorry). The central heating is usualy only used for about an hour in winter before going to bed and that is it. Before fitting the DG and the CH, which have been done only in the last 4 years, we only had a wood stove in the livingroom and an immersion heater for hot water and the original windows as well. The difference DG makes to the livability of a home is massive especially if the home is old pre war stock.

The biggest problem now is I usually go out the close(common stairwell) with the dog in evening and I'm just in a T-shirt to find it blowing a gale and cold and being very surprised.

 

[Jacob]

standard Edinburgh window in old stock builds is single pane sash with internal raised panel shutters. Most of those that have been replaced with DGU still retain the internal shutter as they are expected to be there in older houses. We kept ours when we fitted DG and they are used on very cold nights to keep the heat in. Our shutters are either original (1850's) or at most inter-war replacements as they are old slow growth Scots pine. The density certainly makes a difference. The DG has made a massive difference to quality of life in the flat, no more frost or fractal ice leafs on the inside of the window, calm and quiet (don't even hear the beep of the bin lorry). The central heating is usualy only used for about an hour in winter before going to bed and that is it. Before fitting the DG and the CH, which have been done only in the last 4 years, we only had a wood stove in the livingroom and an immersion heater for hot water and the original windows as well. The difference DG makes to the livability of a home is massive especially if the home is old pre war stock.

The biggest problem now is I usually go out the close(common stairwell) with the dog in evening and I'm just in a T-shirt to find it blowing a gale and cold and being very surprised.

I renovated some vertical sliding shutters some years ago. They didn't know they were there at first and were puzzled by the unused sash pulleys. The shutters dropped into a pocket behind the panelling and the lid closed looked like a normal window cill. They were quite big and dropped below floor level in their boxes.
Re condensation - there's a good argument for saying that it's better to have it on your sash windows rather than on the walls. It drains off and drips away through meeting rail gap and at the bottom sash. You can sometimes see icicles forming outside where it drips. So the single glazed window acts as a de-humidifier.
Also brilliant for draught control and I think Florence Nightingale noted these features and highly recommended them for health reasons

 

[Phil Pascoe]

I commented after fitting my d/g patio doors that the first thing I noticed was the noise reduction - The chap I bought them from said that's the first thing most people say.

 

[Jacob]

I commented after fitting my d/g patio doors that the first thing I noticed was the noise reduction - The chap I bought them from said that's the first thing most people say.

Well yes it's probably the single most useful thing about DG, if you live in a noisy area that is, or work in a noisy workshop.

 

[RobinBHM]

Yes. And if you calculate the annual energy cost difference between "C", "B", "A" and "A+" the difference is very small.

window energy ratings are somewhat of a marketing ploy.

the only difference between a B rating and an A rating is low iron glass.

what does that do? - it’s clearer, so allows more sunlight in, that raises little g value - which is to do with solar gain. Solar gain is pretty useless as we need heating on in the evening in the winter.