dualglaze - cost effective?

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hangon

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#145512 20-May-2014 11:38

Dualglaze ads on tv again

I wonder if anyone has done it and whether it's cost effective retrofit double glaze on un-thermal broken aluminum windows?

What kind of ball park figure to look for when retro fit 3 double bed rooms (1st floor, total window area ~9 sqm), how does it compare with replacing the windows with upvc double glazed units?

Thanks.

MikeAqua

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#1048707 20-May-2014 11:49

In previous house I installed non-thermally-broken double glazed windows in two kids bedrooms.

They were still very effective, and despite being south facing rooms were the warmest and quietest in the house.

Mike

charsleysa

597 posts

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#1048727 20-May-2014 12:18

We got quoted for the downstairs of our house (3 bedrooms, bathroom, toilet, kitchen, lounge laundry) at ~$12,000.

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Stefan Andres Charsley

timmmay

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#1048739 20-May-2014 12:31

You'll still get condensation on the aluminium frames and heat loss, but it will be less overall. I probably wouldn't bother personally, you could do one of the systems where clear plastic sheets go over the whole frame a lot cheaper and it'd possibly be more effective. I have that type of system (from a company that went out of business) in each window frame, along with glass, it made a massive difference to wet windows.

Edit - removed the term PVC, clarified

hangon

397 posts

Ultimate Geek

#1048758 20-May-2014 12:58

Thanks all

Interesting idea about the pvc overlay (magnetic strips I recall?) That might be a good compromise (and looks better than say bubble wraps).

some diy ideas on that discussed here:
http://www.communityenergy.org.nz/secondary-double-glazing/

We considered replacing the aluminum windows with upvc units, but the cost is hardly justifiable as we probably move houses in a few years time.

timmmay

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#1048760 20-May-2014 13:03

They're advertised as magnetic sometimes, but they're better screwed in properly. They do fog up inside sometimes in winter, but since it's winter and it's always dark when I get home I don't much care. It's surprisingly effective as insulation, there's a huge thread on it somewhere.

mattwnz

20141 posts

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#1048797 20-May-2014 13:40

timmmay: You'll still get condensation on the aluminium frames and heat loss, but it will be less overall. I probably wouldn't bother personally, you could do one of the systems where PVC sheets go over the whole frame a lot cheaper and it'd possibly be more effective. I have that PVC system (from a company that went out of business) in each window frame, along with glass, it made a massive difference to wet windows.

The problem I have with PVC is I think they are so damn ugly, and many houses in the UK have them after they pulled out timber ones, and they just look cheap and ugly. These days with new generation thermal isolated aluminum frames, I think they have done away with the need for PVC, especially as alumium windows should be more durable against UV. The other good option is timber, but they are higher maintenance and probably higher cost, unless the outer layer is aluminum.

But back to the OP s question, they maybe better to get some good thermal curtains. Those retro fitted systems do appear to make some difference. However you will end up with condensation on the frames, which will become a problem. I believe you can also get a film you can apply to frames, which will achieve the same sort of result, but at a fraction of the price. Fair go discussed it some time ago, although I don't think too many people here watch that program.

timmmay

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#1049804 20-May-2014 14:48

When I said PVC above I meant clear plastic sheets, like a pane of glass.

I have a PVC window retrofitted into my old house, it looks fine. Not sure I'd want all PVC windows and doors though.

I tried the cheap plastic film that goes over the windows. It was ok, but when I took it off I had to repaint every window as it doesn't come off cleanly. They warp easily, they break, all in all nope don't bother.

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Amosnz

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#1049854 20-May-2014 15:55

I've looked at retro fitting double glazing to a few windows in our house several times, and I always decide the benefit doesn't justify the cost.

Interesting comparison here between the R values of single/double (in various frames) compared to a normal insulated wall. Double glazing doesn't change the R value that much.

http://www.consumer.org.nz/reports/double-glazing/r-values

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mattwnz

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#1049868 20-May-2014 16:09

Amosnz: I've looked at retro fitting double glazing to a few windows in our house several times, and I always decide the benefit doesn't justify the cost.

Interesting comparison here between the R values of single/double (in various frames) compared to a normal insulated wall. Double glazing doesn't change the R value that much.

http://www.consumer.org.nz/reports/double-glazing/r-values

You're right , and that is why in the UK triple glazing is becoming more popular. Double glazing though is still better than single, and it does have the benefit of minimising condensation. Single glazing can just stream with water. In some areas of NZ, I don't believe doube glazing is a requirement for new builds. The other option is laminated glass, but doesn't have the same r values.

It is interesting that those films are almost as effective as a proper IGU. Although their life would be limited.