Triple glazed windows - unreasonable expectations?

dogfonos · 13 Dec 2012

I'd much appreciate views and experiences on these two, related issues...

I'm fed up with condensation forming on my old (mid 80's?) double glazed windows so I'm looking into triple glazing. Current windows throughout the bungalow are polyester powder coated aluminium framed with thermal breaks & approx 25 - 28mm gap between panes.

Every morning from around November to March, I need to mop up water at the base of my existing double glazed windows in the bathroom, bedroom and lounge (patio doors) despite taking care to avoid moisture moving around the place from source, typically kitchen and bathroom.

We have good ventilation in all rooms (bedroom window open 24/7 - unless we're out, bathroom ventilated by open window and air brick, lounge has open chimney and approx 2m of trickle vent on patio doors and all other rooms have high level air bricks). I can see that most of the water has condensed on the window frame rather than the glass.

Can I expect reputable triple glazed replacement windows to elimate condensation entirely? Also, will the (presently very obvious) cold spots in rooms, due to air close to the windows cooling down and causing a down-draft, be a thing of the past?

Thanks in anticipation.

AWMuPVC · 14 Dec 2012

It will be overkill to go for triple glazing; if you were to install uPVC windows with multiple chambers and a good A+ rated glass this will eliminate the condensation problems.

I would recommend using a 28mm 4-20-4 double glazed units with the following spec:

Argon filled air gap
Soft Coat Low-e Glass Panes on both internal and external panes (Saint-Gobain Planotherm glass is very good!)
Warm-edge spacer bars

The low-e glass will retain the heat, the argon will eliminate conduction of cold across the air gap and the warm edge spacer will eliminate conduction of cold by not having a metal spacer bar.

This will make an unbelievable difference to your property! Assuming you have loft and cavity wall insulation as well it will transform your home!

masona · 15 Dec 2012

dogfonos said:
Can I expect reputable triple glazed replacement windows to elimate condensation entirely?

No because the better insulation the more you'll have condensation! Just think if you put a big plastic bag over your house making it air-tight, the moisture is trapped inside can't get out, haven't got time now but do a google search on condensation problem

crank39 · 15 Dec 2012

The trick is to insulate the inner pane from the outer and thats what all these clever dgus with coated glass, gas filled and warm edge spacers try and do nowadays, its trying to keep the inner pane warm when the outer is going to be cold or colder, modern units should be able to manage that so it just means the condensation will find the next cold surface, it won't be easy but you really need to find out why and how your causing it in the first place

foxhole · 16 Dec 2012

Bathroom without mechanical extractor is not good ventilation, same required in Kitchen.

^woody^ · 16 Dec 2012

Triple glazing is only useful as part of a whole-home solution, not just on its own

AronSearle · 17 Dec 2012

crank39 said:
so it just means the condensation will find the next cold surface

Assuming there is another cold surface, and the moisture levels are excessive (seems unlikely with that much ventilation). but wall insulation may be required, and thought will have to be given about the window position in the wall relative to the insulation, and eliminating cold briding from the window lintel.

it won't be easy but you really need to find out why and how your causing it in the first place

I know moisture has to be managed, but why does everyone here seem to completely discount condensation sometimes being a simple matter of cold bridging.

As I understood it, if a surface reaches about 12C in temperature (or 8c less than the air temp), you will get condensation no matter what, that situation doesn't seem unreasonable with old aluminium windows.

AWMuPVC · 17 Dec 2012

AronSearle said:
crank39 said:

so it just means the condensation will find the next cold surface

Click to expand...

Assuming there is another cold surface, and the moisture levels are excessive (seems unlikely with that much ventilation). but wall insulation may be required, and thought will have to be given about the window position in the wall relative to the insulation, and eliminating cold briding from the window lintel.

it won't be easy but you really need to find out why and how your causing it in the first place

Click to expand...

I know moisture has to be managed, but why does everyone here seem to completely discount condensation sometimes being a simple matter of cold bridging.

As I understood it, if a surface reaches about 12C in temperature (or 8c less than the air temp), you will get condensation no matter what, that situation doesn't seem unreasonable with old aluminium windows.

That's what I was saying.. think it is more like 2 degrees and then the air will condense on it. However if the house is warmer and the glass retains heat and does not let it pass through then it will not reach 2 degrees.

masona · 17 Dec 2012

True, also I think it's a lot to do with people lifestyle which can be very difficult to control sometime if plenty of ventilation is done then the only other option is a dehumidifier but even that produce warm moisture back into the room. In my childhood days we never had condensation problems specially with draughty leadlight windows plus airy fireplaces and floorboards. I'm being to wonder if bungalow have more condensation than houses?

AronSearle · 18 Dec 2012

The problem is that we have loads of houses with poor to none wall insulation, but with modern windows, generally more airtight, and modern heating systems.

So you end up with warmer air, but still lots of cold surfaces due to poor building insulation, cold bridging from lintels or thermal gaps around windows and ceiling corners, or floor corners where the floors are concrete.

And this means having to ventilate to both lower the moisture levels and air temperature (reducing the thermal difference between air and cold surfaces).

If you are only getting condensation on the window frames, it may be replacing them, and ensuring they are fitted within the insulation envelop will stop condensation.

But as said, it will "move" if the overall insulation levels are still poor, as you will still end up with spot's much colder than the ambient air temperature = condensation.

I don't at all discount managing moisture and ensuring adequate ventilation, but our housing stock is so poor and we are never going to improve energy efficiency if we over-ventilate as the only solution against condensation.

dogfonos · 7 Feb 2014

For reasons I can't fathom, I'm not receiving email notification when someone replies to one of my watched threads (such as this one - and it's happening on other forums too) so a (very) belated thanks for all the replies that I've only just seen.

Just for completeness, I'll add that the bungalow is very well ventilated (IMO) and has cavity wall and loft insulation. A consumer-level humidity monitor (i.e. not calibrated) typically reads between 40 and 60% relative humidity (only going higher during seriously damp spells). Kitchen has fan extraction, which is always used when cooking and left on for about an hour afterwards. Bathroom does not have fan extraction - just a largish opening window which is always left open for at least half an hour - often more - following showers/baths.

Nice explanation of condensation on Wiki. There's a really useful chart about halfway down the page that identifies the conditions under which condensation occurs (i.e. at the dew point):
http://en.wikipedia.org/wiki/Dew_point

God · 7 Feb 2014

Double glazing will never eliminate condensation, it will reduce it. Most condensation problems are probably due to lifestyle and bad ventilation. As said houses are becoming more airtight adding to condensation problems

dogfonos · 7 Feb 2014

Yes, I've seen enough modern houses with damp/condensation issues. In contrast, my bungalow appears to have generous ventilation and we carefully manage the high moisture areas. There are no damp wall or ceiling issues either which makes me lean towards the window cold-bridging theory rather than a general damp atmosphere issue.

I'll borrow a mate's contact thermometer and take some temperature measurements of internal window frames. Using these measurements and the dew point chart I referred to in my last post, I should be able to determine if it's purely a window problem or the air is just too damp.

pinenot · 8 Feb 2014

Condensation is the ability of moisture in the rooms atmosphere to condense on a cold/dew forming surface! Moisture is always in the air, Old (pre 1940ish) houses were built to breath through most of their large surfaces and they had drafts (ventilation), modern homes are built both of waterproof materials and fairly draft free, so no breath ability and limited ventilation.
The upshot is if you take care of all of the above, not just one, you will be able to cure the condensation.
You can measure the relative humidity of a room with a fairly inexpensive piece of equipment, called a hygrometer (moisture meters are useless) about a tenner from B&Q, this will tell you what humidity the room is at any given time.
Do you have to mop up the condensation before you go to bed? ...pinenot

dogfonos · 8 Feb 2014

Do you have to mop up the condensation before you go to bed?

When I get up in the morning.
I need to wedge a few layers of loo roll at the base of DG, aluminium-framed patio doors in the lounge before we turn in. If outside overnight temperature has been below about 3 or 4C, the tissue is soaking wet in the morning but at least it stops water running away through the wood surround/skirting board. The door to this room is closed overnight and is ventilated to outside by a substantial (2m) long vent above the patio doors (fully or partially open or nominally closed makes no difference to condensation levels) and there's an open fireplace with a letter-box sized opening in the firebox to the chimney.

Saw an interesting article from 2012 in the Telegraph:

http://www.telegraph.co.uk/property...t-is-the-recommended-humidity-for-a-home.html

It suggests that the installation of cavity wall insulation can make the condensation problem worse - ties in with your point about home breathability. Condensation has always been a problem in my place but it might be a little worse since the cavity wall insulation was installed - difficult to be sure.

The same Telegraph article suggested the recommended relative humidity in a British domestic property should be around 50 to 55% - which it is in my home (assuming the humidity monitor is reading correctly).

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Triple glazed windows - unreasonable expectations?

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