Triple glazing worth it

Grizebeck

Trying to work out if tripple glazing is worth it.
House is in the North East south facing 
Not near a main road and area is quiet 
Just wondering if to go for it or is the extra money a wasted spend

ThisIsWeird

It depends on the improved U-value, and the additional cost. And almost certainly on how much glass area is involved.
We had 4m bi-folds fitted in a 6m wall, and the extra cost for triple was less than £200, so a no-brainer. I didn't even bother comparing U values - it just seemed obvious that any improvement over what was most of one external wall would be sensible - and I also thought it would sound good when we sold :-(
For, say, just one or two windows, the overall improvement in insulation value for that whole room might be pretty insignificant, so 'not worth it' unless little extra cost.
I guess it'll also matter what the rest of the external walls are made of, and how well insulated? 
It's also heavier, which might matter on hinged windows?
Single to double is obviously a huge improvement. Double to triple is slight.
So, what are we talking about in your case? 

ComicGeek

What no one ever mentions is that triple glazing blocks out more direct sunlight than standard double glazing, sometimes as much as 50% more.

Can be good in the summer for south and west facing windows to reduce solar heat coming in (if the room currently overheats in summer), but also significantly reduces beneficial solar heat gain in the winter months which in turn increases energy costs from heating.

Grizebeck

@ThisIsWeird thanks its a whole house refurb and @ComicGeek I didn't know that so I think that in itself has probably made my mind up.

grumbler

ComicGeek said:

...triple glazing blocks out more direct sunlight than standard double glazing, sometimes as much as 50% more.

It's very hard to believe that an extra sheet of clear glass can block even 50%, let alone more.

FreeBear

ThisIsWeird said: It's also heavier, which might matter on hinged windows?

Depending on the construction, a sealed unit of the same size could weigh more. But if the middle pane uses a super thin sheet like the Corning ATG, the weight difference will be minimal.

Changes to Building Regulations are in the pipeline and due to come in to force in 2025 which will mean triple glazing is likely the only way to hit the required u-value. If the cost uplift is minimal today for sealed units that hit tomorrows targets, it makes sense to go with the higher spec ones.

ThisIsWeird

Re the '50% sun block' effect, I cannot comment as ours is north-facing, so solar gain - or blocking - isn't an issue. But, clarity certainly was as we have views. And they do not impact at all. 
In fact, to see these views from the rest of the house, we look through the existing large double-glazed windows into the extension, and then out through the bi-folds. Penta-glazed! Clear as a clear thing.

grumbler

grumbler said:

ComicGeek said:

...triple glazing blocks out more direct sunlight than standard double glazing, sometimes as much as 50% more.

It's very hard to believe that an extra sheet of clear glass can block even 50%, let alone more.

On second thought, if double glazing blocks, say, 4%, i.e. 2% per a pane, then I'd expect a third pain to block 2% too, i.e. 6% in total, 50% more. Not a big deal really.  50% of nothing is nothing.

EssexExile

We have triple glazing almost everywhere. The sound insulation is noticeably better than double glazing but temperature wise it's difficult to tell. We had a lot of work done when it was fitted and it didn't make much difference to the total cost.

I've not noticed any great reduction in the heat of the sun through the triple glazing, the room with bi-folds across one end still gets hot in the summer.

ComicGeek

grumbler said:

grumbler said:

ComicGeek said:

...triple glazing blocks out more direct sunlight than standard double glazing, sometimes as much as 50% more.

It's very hard to believe that an extra sheet of clear glass can block even 50%, let alone more.

On second thought, if double glazing blocks, say, 4%, i.e. 2% per a pane, then I'd expect a third pain to block 2% too, i.e. 6% in total, 50% more. Not a big deal really.  50% of nothing is nothing.

Standard double glazing has a g-value of 0.73, ie 73% of the solar heat gain is allowed through the glass, 27% is blocked. Much, much higher than 4%!!

Triple glazing can have g-value down to 0.34, ie only 34% of the solar heat gain is allowed through, 66% is blocked.

Also, the frame of triple glazing units are normally thicker than double glazed, so the amount of glazing in a window is usually less, further reducing the window g-value.

Albermarle

ComicGeek said:

grumbler said:

grumbler said:

ComicGeek said:

...triple glazing blocks out more direct sunlight than standard double glazing, sometimes as much as 50% more.

It's very hard to believe that an extra sheet of clear glass can block even 50%, let alone more.

On second thought, if double glazing blocks, say, 4%, i.e. 2% per a pane, then I'd expect a third pain to block 2% too, i.e. 6% in total, 50% more. Not a big deal really.  50% of nothing is nothing.

Standard double glazing has a g-value of 0.73, ie 73% of the solar heat gain is allowed through the glass, 27% is blocked. Much, much higher than 4%!!

Triple glazing can have g-value down to 0.34, ie only 34% of the solar heat gain is allowed through, 66% is blocked.

Also, the frame of triple glazing units are normally thicker than double glazed, so the amount of glazing in a window is usually less, further reducing the window g-value.

Presume though it does not block 66% of the light though ( just the heat) ? The house would be a bit gloomy if it did !