Does triple glazing make sense in a new house?
Discussion
I have no experience or knowledge so would appreciate feedback on this. We're getting building quotes which include triple glazing. Will we notice the difference between double/triple? Are there any other conditions which need to be satisfied to make triple worthwhile? What is the likely difference in price for the two varieties? Knowing that, what is the likely payback time? Are there any other questions I should be asking myself?
All advice gratefully received. Would hate to make the wrong, expensive decision.
All advice gratefully received. Would hate to make the wrong, expensive decision.
I doubt the payback time will be before your funeral, but no doubt there will eventually be a Government scrappage scheme to save carbons and meet some random targets.
Unless you live in Finland or Northern Canada I can't see the point really.
ETA: I hear that the most thermally weak point of windows is now the frame, so unless they've fixed that...
Unless you live in Finland or Northern Canada I can't see the point really.
ETA: I hear that the most thermally weak point of windows is now the frame, so unless they've fixed that...
Edited by Simpo Two on Tuesday 26th January 15:36
A lot depends on where you're building. If your profile is to be believed and you're in Germany, then quite possibly. Triple glazing reduces heat losses, and if you live in a harsh climate that will be a significant part of your heating bill. In the south of England, the benefit is much less.
However, you need your architect to do a full analysis. Glazing can contribute to heating (solar gain) as well as leaking heat. A lot will therefore depend on the amount of glass on each side of your house (south is good - solar gain, north is bad - heat loss).
Triple glazing does have a noticeable effect on the light coming into your home, so I wouldn't necessarily specify it just for the sake of it.
You need to research similar homes to get a feel for it.
However, you need your architect to do a full analysis. Glazing can contribute to heating (solar gain) as well as leaking heat. A lot will therefore depend on the amount of glass on each side of your house (south is good - solar gain, north is bad - heat loss).
Triple glazing does have a noticeable effect on the light coming into your home, so I wouldn't necessarily specify it just for the sake of it.
You need to research similar homes to get a feel for it.
Simpo Two said:
I hear that the most thermally weak point of windows is now the frame, so unless they've fixed that...
If you're looking at triple glazing, you're probably looking at thermally broken frames rather than cheapo uPVC. The cost of triple v's double can be relatively small for well specc'd frames, so if the climate warrants it, it's worth considering.Edited by Simpo Two on Tuesday 26th January 15:36
I'm currently building a North face extension and am going to specify triple glazed thermally broken units myself. They do make a great difference, I've witnessed their use in Germany. You have the added advantage of being able to make use of the second void for integral blinds etc also.
Yes they are obviously more expensive, but I think it's the way things are going and they are becoming more common in the UK
Yes they are obviously more expensive, but I think it's the way things are going and they are becoming more common in the UK
Whether it is double or triple glazed is not the point. It is the U value you should be looking at.
A regular double glazed window these days is 4/20/4 and will consist of something like Pilkington K glass, thermix spacer bar, argon gas filled and Pilkington optiwhite (or generic equivalents from other brands). It will have a U value of around 1.1 and a B energy rating, triple glazing won't improve on that, may even make it worse as you can't argon fill.
The only reason for triple glazing these days is if you want lead/stains/bevels and you put them on the inside to stay clean.
Even if noise reduction is the goal, triple glazing is no good. Secondarys with a big gap, or a DG unit at 10/11.7gap/6.3lam is technically the best acoustic reduction on a 28mm unit, not triple glazing.
A perfectly boggo standard DG window with an A or B energy rating will be just fine.
If you live in the arctic, double them up
btw, regarding thermally broken, you only need that if the frame material is not thermally efficient, such as aluminium, so it will be split and rejoined with a thermal break. PVCu does not need that, as it is in itself the similar sort of stuff they make the thermal break with anyway.
I stand to be corrected, but if I am, I bet you're looking at some 'Grand Designs' style stuff at silly money, rather than a regular UK product.
A regular double glazed window these days is 4/20/4 and will consist of something like Pilkington K glass, thermix spacer bar, argon gas filled and Pilkington optiwhite (or generic equivalents from other brands). It will have a U value of around 1.1 and a B energy rating, triple glazing won't improve on that, may even make it worse as you can't argon fill.
The only reason for triple glazing these days is if you want lead/stains/bevels and you put them on the inside to stay clean.
Even if noise reduction is the goal, triple glazing is no good. Secondarys with a big gap, or a DG unit at 10/11.7gap/6.3lam is technically the best acoustic reduction on a 28mm unit, not triple glazing.
A perfectly boggo standard DG window with an A or B energy rating will be just fine.
If you live in the arctic, double them up
btw, regarding thermally broken, you only need that if the frame material is not thermally efficient, such as aluminium, so it will be split and rejoined with a thermal break. PVCu does not need that, as it is in itself the similar sort of stuff they make the thermal break with anyway.
I stand to be corrected, but if I am, I bet you're looking at some 'Grand Designs' style stuff at silly money, rather than a regular UK product.
Edited by Balmoral Green on Tuesday 26th January 18:00
Balmoral Green said:
It will have a U value of around 1.1 and a B energy rating, triple glazing won't improve on that, may even make it worse as you can't argon fill.
I didn't look too deeply into it as we quickly decided that triple glazing was irrelevant on our house (south-east england, relatively low glazed area). However, I'm pretty sure that triple glazed units easily beat a whole-window u-value of 1.1 - I've seen values as low as 0.7 quoted.Balmoral Green said:
Whether it is double or triple glazed is not the point. It is the U value you should be looking at.
A regular double glazed window these days is 4/20/4 and will consist of something like Pilkington K glass, thermix spacer bar, argon gas filled and Pilkington optiwhite (or generic equivalents from other brands). It will have a U value of around 1.1 and a B energy rating, triple glazing won't improve on that, may even make it worse as you can't argon fill.
The only reason for triple glazing these days is if you want lead/stains/bevels and you put them on the inside to stay clean.
Even if noise reduction is the goal, triple glazing is no good. Secondarys with a big gap, or a DG unit at 10/11.7gap/6.3lam is technically the best acoustic reduction on a 28mm unit, not triple glazing.
A perfectly boggo standard DG window with an A or B energy rating will be just fine.
If you live in the arctic, double them up
btw, regarding thermally broken, you only need that if the frame material is not thermally efficient, such as aluminium, so it will be split and rejoined with a thermal break. PVCu does not need that, as it is in itself the similar sort of stuff they make the thermal break with anyway.
I stand to be corrected, but if I am, I bet you're looking at some 'Grand Designs' style stuff at silly money, rather than a regular UK product.
I am looking at the Internorm Alu/ timber triple glazed units produced in Austria www.internorm.co.uk . They are quoting a U value of 0.68 w/m2 for their standard units. These are indeed produced in Austria and are more expensive, but the quality is excellent (my mates house in Baveria has them) If any one knows of any UK manufacturer that can produce at a similar quality let me know, as we all know the good old English £ is not doing very well at the moA regular double glazed window these days is 4/20/4 and will consist of something like Pilkington K glass, thermix spacer bar, argon gas filled and Pilkington optiwhite (or generic equivalents from other brands). It will have a U value of around 1.1 and a B energy rating, triple glazing won't improve on that, may even make it worse as you can't argon fill.
The only reason for triple glazing these days is if you want lead/stains/bevels and you put them on the inside to stay clean.
Even if noise reduction is the goal, triple glazing is no good. Secondarys with a big gap, or a DG unit at 10/11.7gap/6.3lam is technically the best acoustic reduction on a 28mm unit, not triple glazing.
A perfectly boggo standard DG window with an A or B energy rating will be just fine.
If you live in the arctic, double them up
btw, regarding thermally broken, you only need that if the frame material is not thermally efficient, such as aluminium, so it will be split and rejoined with a thermal break. PVCu does not need that, as it is in itself the similar sort of stuff they make the thermal break with anyway.
I stand to be corrected, but if I am, I bet you're looking at some 'Grand Designs' style stuff at silly money, rather than a regular UK product.
Edited by Balmoral Green on Tuesday 26th January 18:00
We got ours (alu-clad oak, double glazed) from http://www.rawington.com - they import from Eastern Europe and deliver a good product at a good price. Tell them you were given their details from the guy at Lock Farm.
Alternatively, Rembrandt Timber in Scotland gets regular mentions, but I've not heard of anyone with their products so can't vouch for the quality. Their quoted U-values are a bit disappointing though.
Alternatively, Rembrandt Timber in Scotland gets regular mentions, but I've not heard of anyone with their products so can't vouch for the quality. Their quoted U-values are a bit disappointing though.
I think, for the money, you can save more heat loss through other means than going triple glazing versus double glazing. i.e. how deep is your cavity? Look to have that at least 100mm or even more... How much insulation are you looking to put in the floor? How much insulation are you looking to put in the roof structure or ceiling?
Balmoral Green said:
Even if noise reduction is the goal, triple glazing is no good. Secondarys with a big gap, or a DG unit at 10/11.7gap/6.3lam is technically the best acoustic reduction on a 28mm unit, not triple glazing.
Sorry to take this off tangent but can I pick your brain on the noise point Warren? Looking to re window front of our Victorian house and being near a road cutting out traffic noise is number one priority. Currently have old aluminium framed dg units set within what would have once been outer frame box section parts of an original sash. Wanting to go back to timber and to look as original as poss (but going full sash has been ruled out due to the noise reduction needed). A decent appearing company has come out suggesting they can make us up hardwood units (similar to the the aluminium there currently) to house 6.4 laminated/14 gap/ 4mm (toughened I think) dg units (pilkington K, argon filled). Does that sound a reasonable solution to you as well, layman thought would be that we should have thicker glass but he did talk about the airgap being crucial and the thicker the glass then narrows the space... it all starts to make me a bit 
. Total depth is limited by using timber and what we are setting the new bits into. 25mm I guess it works out at.. If you were speccing a DG unit with that depth for sound, what you would go for. I'd rather overspec than under as it's an expensive business to get wrong!! I know secondary glazing is better still for noise but we would ideally like to achieve a solution within the window for aesthetic reasons. OK thanks for all the feedback. Got the answer on price differential today and waiting more info for the U values. Apparently the difference for a 3 bedroomed house with a ground plan of 10.7m x 9.7m external dimensions is 1,200 euros and the difference for underfloor heating versus conventional radiators is 1,800 euros. Other things being equal, I think I will go with both of those options. Let me know if you think I am making a mistake.
ETA plastic frames
ETA plastic frames
Edited by paul.deitch on Wednesday 27th January 20:09
Just a note on the insulation values open to any comment. Its the KfW 70 German insulation which apparent means it uses 70% of the energy of some standard house requirements.
"Der Jahres-Primärenergiebedarf und der Transmissionswärmeverlust dürfen maximal 70 % der nach EnEV2007 zulässigen Werte erreichen. Der Jahres-Primärenergiebedarf ist auf maximal 60 kWh/m² Gebäudenutzfläche beschränkt."
It will use a max of 60kwh/m2 per year - is this good?
"Der Jahres-Primärenergiebedarf und der Transmissionswärmeverlust dürfen maximal 70 % der nach EnEV2007 zulässigen Werte erreichen. Der Jahres-Primärenergiebedarf ist auf maximal 60 kWh/m² Gebäudenutzfläche beschränkt."
It will use a max of 60kwh/m2 per year - is this good?
touching cloth said:
6.4 laminated/14 gap/4mm (toughened I think) dg units (pilkington K, argon filled).
That's a standard spec laminated unit really. I'm sure it offers a noise reduction benefit over a standard non-laminated unit, but probably not by much.With secondarys, the bigger the gap, the better, which will be dependent upon the recess depth.
With DGU's at 24/28mm, it's probably splitting hairs. But the bods at Pilkingtons told me that the spec I mentioned above is the best for noise reduction with a 28mm DGU. Bloody heavy though, so window size is a factor if it's an opener too.
Thanks for that, don't suppose you cover Berkshire do you?? Chap who suggested that did seem pretty on the ball when he came but having played around on Pilkington's website (they have a sounds simulator thing) there seem to be some other options like "optiphon" glass which he hasn't suggested. It's going to be expensive so I really don't want to get it wrong, even if getting it right costs me more money... if that makes sense!!
Anyway sorry for hijack OP, thread returned.
Anyway sorry for hijack OP, thread returned.
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