Triple glazing in a 1930s building

[European_Del]

Hello all,

There are a few triple glazing threads, but I haven't quite found a response to the following question:

Living in an apartment in a 1930s house with poor insulation (walls uninsulated, no insulation in the attic), and wondering whether triple glazing is a good idea or will double glazing be more appropriate? We've had a few quotes for new windows and the one person who spent a bit of time here and explained various things which chimed with us was the only person to suggest triple glazing. The main argument was that this is going to be the standard in a few years, so might as well invest now. It's about 700 euros more expensive in total for the four windows that we're going to change (based in France).

However, after a bit of research online, it seems that for older houses like ours, triple glazing could actually be less suitable than double glazing (reduced benefit of heat from sun in winter, condensation more likely to form on uninsulated walls rather than windows causing damp issues etc.). It's unlikely that we'll insulate the walls as we need all the neighbours in the building to agree, and we plan on moving in 6-7 years to somewhere slightly bigger.

So I'm wondering whether anyone has had triple glazing installed in a similar context and what their experience was? Would it change anything in terms of the attractiveness/value of the property when we sell?

 

[blup]

Surely much more effective to insulate walls roof and floors, plus dg.

Blup

 

[robinbanks]

wondering whether triple glazing is a good idea or will double glazing be more appropriate?

In a nutshell, unless it's a fraction dearer than double, save the money on the uplift and spend it on insulation for walls and roof instead

 

[ronniecabers]

Triple will not just be a 'fraction 'more expensive than double lol, that I can assure you, as has been mentioned your money will be much better spent elsewhere

 

[Diver Fred]

You will get condensation on the walls with double glazing. If you have issues with condensation (or damp) on walls now it will be much worse with a glazing upgrade (to double or treble glazing).
As others have said money is better spent on loft and wall insulation. if you go the double glazing route first then also spend some cash on a positive ventilation system as well.

 

[robinbanks]

Double glazing "causes condensation"?

Can you expand on the logic behind that one, Fred?

 

[Diver Fred]

Simple if you have condensation on glass now you are less likely to see it on walls, particularly with cavity walls. But with solid (9inch) walls which are inherently colder will presently have condensation occurring. Putting double glazing in where there is poorly insulated walls and you will have less condensation on the glazing but more on the walls.

Double glazing is a form of insulation. Where the water vapour condenses moves to the coldest surfaces.

 

[robinbanks]

I understand all that, but I think it's a bit weak to say it's causing. The cause is excess moisture generation relative to the air's capacity to hold it, for some given temperature.

The way you've described it, it's like a single pane window is a ideal dehumidifier capable of collecting all the moisture in the room, keeping the walls dry; it's not so black and white - the walls encourage condensation too because they are also cool surfaces

 

[Diver Fred]

Where did I say DG causes condensation? Most people don't see condensation on walls until they install DG. Those that do see condensation on walls before DG either dry clothes and towels on radiators or have as very cold room where it is worse, typically bathrooms.

 

[ronniecabers]

To say you will get condensation on walls after fitting double glazing is very misleading. There are many factors that influence condensation. A better statement would be ' beware if you fit modern double glazing and you currently get a lot of condensation as you may find condensation in other places in the property as they maybe colder than the windows , address why so much water borne vapour, using ventilation and heat '

 

[crank39]

Its all about the dew point, the dew Point is the temperature at which moisture will condense out of the air. If the temperature of any surface is at or below the dew point temperature then dew (condensation) will form.

Here are some examples of Dew Point conditions:

• 85°C and 85% RH, the Dew Point is 80.9°C
• 23°C and 50% RH, the Dew Point is 12°C
• 23°C and 10% RH, the Dew Point is -10°C
• 0°C and 50% RH, the Dew Point is -9°C
• 0°C and 10% RH, the Dew Point is -28°C
• -20°C and 50% RH, the Dew Point is -28°C
• -20°C and 10% RH, the Dew Point is -44°C

So its a case of keeping temperatures of surfaces above the dew point, fitting double glazing may help to stop condensation forming on the glass as in theory with modern glass and warm edge spacers the inner pane should retain heat and not be cooled by the outside temp, this does not mean the condensation will decide to condensate elsewhere for the fun of it, that 'elsewhere' surface has to be at or below the dew point for condensation to form on it. Whilst double glazing may help it could just as easily make it worse, modern windows are thermally very efficient, air tight and draft free if you ignore the trickle vent thing

Stopping condensation is a combination of a few things, cut down as much as possible on activities that create moisture, ventilation and keeping rooms(surfaces) above the dew point

 

[Notch7]

Triple glazing means the temperature of the surface of the internal pane is warmer, so the air near the windows will feel warmer.

If the windows are near where you sit, say a sofa or dining table it might be worthwhile.


but in terms of thermal benefit: going from double to triple is the law of diminishing returns.


U values (roughly)

single glazing 4.0
best double 1.2
triple 0.8


The latest double glazing is so effective, on cold mornings condensation can form on the outside.

go for soft coat low e, warm edge spacer, argon gas fill.

and low iron glass if solar gain if aspect creates a benefit.

 

[robinbanks]

And make it part of a comprehensive set of works to upgrade the insulation and draughtproof the property. Fit an MVHR if you have the spare cash

 

[European_Del]

Hello all,

Thanks for the comprehensive responses. Going to go with DG (the windows being changed are also DG by the way, just aging badly due to being poorly fitted and of poor quality). Roof insulation is en route. Going to insulate the coldest room walls from the inside and install a mechanical ventilation system. Had no visible problems with condensation on walls / windows before now.

 

[robinbanks]

install a mechanical ventilation system

Which one, specifically?