Triple glazed windows into un-insulated house

e92335i

1980 house renovation - Budget does not stretch to dry lining house so we have existing Cavity wall with 40/50mm aeroboard insulation. Planning to pump the remainder of the cavity with kingspan ecobead

There are large windows throughout the house (2.16m x 1.7m ground floor and 2.16x 1.25 1st floor)

When replacing Windows will I see any benefit with the triple vs double in the scenario above?

BryanF

Triple. Buy the best you can. Think about how they are installed to achieve continuity with insulation in the cavity and air-tightness with the

Who2

If your along a busy or noisy area the triple glazed are good for noise. If not the thermal value of a top of the range double glazed window with insulated frame is negligible on an older type house. Something to bear in mind is the fact with triple glazed you will have a far heavier sash so if your going with a full height ope you will be maxing out the weight the hinges and fixings can take . The price difference is minimal but I’d say the longevity of hinges will be the main issue.

BryanF

Who2 wrote: »

If your along a busy or noisy area the triple glazed are good for noise. If not the thermal value of a top of the range double glazed window with insulated frame is negligible on an older type house. Something to bear in mind is the fact with triple glazed you will have a far heavier sash so if your going with a full height ope you will be maxing out the weight the hinges and fixings can take . The price difference is minimal but I’d say the longevity of hinges will be the main issue.

Negligible?

What’s the best double glazing units you supply?

If the best of double is 1.1wm/2 and triple is as low as 0.6wm/2 that’s a big difference?

Who2

BryanF wrote: »

Negligible?

What’s the best double glazing units you supply?

If the best of double is 1.1wm/2 and triple is as low as 0.6wm/2 that’s a big difference?

Most are 0.9 some down to 0.8. If your buying budget 60mm frames of course it will be 1.1 and even worse but a good grade properly insulated frame with warm edge glass will usually hit .8. There are plenty of triple glazed windows still only at .9

Who2

BryanF wrote: »

Negligible?

What’s the best double glazing units you supply?

If the best of double is 1.1wm/2 and triple is as low as 0.6wm/2 that’s a big difference?

Also where do you get the impression I supply windows, because I don’t.

BryanF

Who2 wrote: »

Most are 0.9 some down to 0.8. If your buying budget 60mm frames of course it will be 1.1 and even worse but a good grade properly insulated frame with warm edge glass will usually hit .8. There are plenty of triple glazed windows still only at .9

Double Below 1w/m2k ? Can you direct us a data sheet? Thanks

Who2

BryanF wrote: »

Double Below 1w/m2k ? Can you direct us a data sheet? Thanks

Munster j future proof window first example

Wartburg

Be careful when installing high spec triple glazed windows in existing houses with weaker insulation performance. The glazing should be the coldest spot in the room to visualize condensation problems. In case the window is better insulated than other parts of the building envelope, you will not see the problem of condensation until the wall or ceiling is covered with mould.

Some window manufacturer in Eastern Europe do offer quadruple glazing meanwhile. The backside of the coin is the weight of the glazing and the manufacturing costs. Bear in mind that glass manufacturing requires plenty of energy. I´ve seen some prototypes of vacuum-glazing years ago at the Fensterbau window exhibition in Nuremberg. Double glazing with an overall thickness of 9mm and far better values than any other glazing.

BryanF

Wartburg wrote: »

Be careful when installing high spec triple glazed windows in existing houses with weaker insulation performance. The glazing should be the coldest spot in the room to visualize condensation problems. In case the window is better insulated than other parts of the building envelope, you will not see the problem of condensation until the wall or ceiling is covered with mould.

Some window manufacturer in Eastern Europe do offer quadruple glazing meanwhile. The backside of the coin is the weight of the glazing and the manufacturing costs. Bear in mind that glass manufacturing requires plenty of energy. I´ve seen some prototypes of vacuum-glazing years ago at the Fensterbau window exhibition in Nuremberg. Double glazing with an overall thickness of 9mm and far better values than any other glazing.

The OP has cavity insulation and intends pumping the remaining cavity. 50mm eps cavity insulation is still better than the same as quadruple glazing, never mind double.

That must be some glazing in Nuremberg exhibition. but the last line reads like you are suggesting double glazing is better than triple?

BryanF

Who2 wrote: »

Munster j future proof window first example

Data sheet please? The one I have says 1.2 w/m2k

the_pen_turner

go with the best availible. you will upgrade the insulation later. if you go for lesser windows now you will have to upgrade them again or live with their only ok performance

Wartburg

BryanF wrote: »

The OP has cavity insulation and intends pumping the remaining cavity. 50mm eps cavity insulation is still better than the same as quadruple glazing, never mind double.

That must be some glazing in Nuremberg exhibition. but the last line reads like you are suggesting double glazing is better than triple?

There´s always a difference between theory and reality. The best example is the fuel consumption of the vehicles of us all.

Unfortunately there´s not that much difference when it comes to u-values for insulation materials in the construction industry. Obvious simple materials like eps insulation boards for ETICS do mostly not achieve the specified value, because it is very hard (and expensive) in the industrial manufacturing process to create these boards with good thermal conductivity values like 0.032W/m²K permanently.
On top there´s always another weakening caused by installation, because we´re all humans and not perfect robots.
Some details in the building do work contrary to the best theoretical u-values too. My all-time favourite is the (nuisance) corner window with steel post.
Another problem is the diffusion behaviour of every gas, no matter if it´s called Argon, Krypton or whatever. Researches in recent years have shown that the gas filling of the double or triple glazing have completely disappeared after years.
The more panes you´re using for your glazing, the less solar gain and transparency you have. It could end the way, that what you save on the u-value of the glass is what you pay more for heating and light.

Don´t get me wrong - I´m not suggesting that a certain type of glazing is the best for every purpose. I highly recommend to do some research and calculation for every individual case. Ideally by someone independent, who´s not working for the business that wants to sell the product.
And the most important aspect is always the proper installation with the required attention to insulation, thermal bridging and air tight sealing around the windows.

e92335i

Hi All,

Thanks for your feedback. Difficult to decipher what is best here.

See below layout of the house with sun position:
sun.JPG
I'm thinking North and east facing windows to have triple glaze:
rear.JPG
Gable.JPG
South facing windows to have Double glaze:
front.JPG

Is this my best strategy?

Lumen

You might be overthinking it. Get triple glazing everywhere.

If you want to overthink it even more, and arrive at the same conclusion, read this:

http://www.markstephensarchitects.com/why-have-triple-glazed-windows-passivhaus-3-solar-gains-a-bit-more-g-value/

Therefore on balance (which is an important word here as it is a heat balance calculation) in this location (Dublin) the optimum window is triple glazed

Wartburg

Lumen wrote: »

You might be overthinking it. Get triple glazing everywhere.

If you want to overthink it even more, and arrive at the same conclusion, read this:

http://www.markstephensarchitects.com/why-have-triple-glazed-windows-passivhaus-3-solar-gains-a-bit-more-g-value/

That´s exactly that kind of difference between theory and reality, I mentioned in my last post. Your architect is comparing the glazing only, but not the complete window.
The thermal conductivity of triple glazing is better in comparison to every avaliable window frame material, which means that the overall window value is worse than the 0.6W/m²K, coming of the glass. Good triple glazed windows have an overall thermal conductivity of around 0.8W/m²K (mostly closer to 0.9W/m²K). Double glazed will stay around 1.2W/m²K. That means by the end, that the transmission loss of the double glazed unit is not almost two times more as stated in the architects calculation. In this case it would end with a Qt of 72kWh/a (double glazing) to 48kWh/a (triple glazing). That means the triple glazed window is still 24kWh/a better. Remember that the double glazing has the better solar gain plus the better transparency as well, so the difference between the two glazing strategies goes further down. I read another interesting fact about the wavelength of light which gets blocked by triple glazing (best regards to Vitamin D).

Once again - just an independent calculation, which takes attention to all aspects, can bring light into the dark, which glazing the user e92335i should select for his project.

Lumen

I don't really see what how the frame performance is relevant since we're comparing glazing performance, so the frame is not a variable. The contributions to u-value and area will cancel out.

The visible light transmittivity difference is theoretically significant because you could reduce heat losses by specifying fractionally smaller windows with marginally better transmittivity, but since our eyes come equipped with irises the perceptible difference is going to be √(bugger all), and nobody does that anyway, do they?

fatty pang

Who2 wrote: »

If your along a busy or noisy area the triple glazed are good for noise.

In the vast majority of situations double-glazing will provide better potential for sound reduction then triple-glazing.

fatty pang

Lumen wrote: »

I don't really see what how the frame performance is relevant since we're comparing glazing performance, so the frame is not a variable.

Additionally, the better purpose designed triple-glazed systems will be often able to accommodate larger sash sizes which can facilitate a reduction in transoms and mullions, reducing cost (and Uw-value) and significantly increasing glass to framing ratio ...Not to mention improving the aesthetics

Who2

fatty pang wrote: »

Additionally, the better purpose designed triple-glazed systems will be often able to accommodate larger sash sizes which can facilitate a reduction in transoms and mullions, reducing cost (and Uw-value) and significantly increasing glass to framing ratio ...Not to mention improving the aesthetics

Can you describe the purpose designed triple glazing system .

BryanF

fatty pang wrote: »

In the vast majority of situations double-glazing will provide better potential for sound reduction then triple-glazing.

Can you forward a peer-reviewed study in this? Thanks

Lumen

BryanF wrote: »

Can you forward a peer-reviewed study in this? Thanks

Here is an interesting study from 1988. I have no idea of its peer reviewing status.

http://web.mit.edu/parmstr/Public/NRCan/CanBldgDigests/cbd240_e.html

Triple glazing in itself offers no benefits at normal pane separations. The air in the voids acts like a spring. What's important is:

1. Total mass of glass, i.e. sum of thickness of all panes. Higher mass = lower noise.
2. Distance separating panes. Greater separation = lower noise, although very large separation is required to achieve this (50mm is suggested in another paper).
3. Using different pane thicknesses.
4. Laminating glass panes with plastic, because the plastic layer adds extra damping (although it also states that plastic has the same performance for a given mass as glass, so maybe this is really just a variation of (3)).

Distributing the same mass of glass between three panes rather than two offers no net benefit, it enables (3) but tends to prevent (2) and (4).

In cases where substantial noise reduction is required, double glazing is the most sensible choice. The airspace should be sufficiently large to provide the desired TL.

Or to put it another way, if you want good acoustic performance, don't get triple glazing with three equally thin panes, or even triple glazing with different glass pane thicknesses, get widely spaced double glazing with one laminated pane and a second pane of different thickness, and get the thickess panes you can find.

Lumen

Here's a data sheet from an Irish company giving acoustic performance of different permutations of panes in single and double glazed configurations.

Can anyone find similar for triple?

Note: Pilkington Optiphon is an acoustic laminated glass, so this is useful for comparing that to non-acoustic glass which is on the lower part of the page.

As for which frequencies matter, here is a limited study showing risk of hypertention is greatest at 125Hz.

http://www.firstglass.ie/brochures/Pilkington%20Optiphon%20Data%20Sheet.pdf