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  # 2310818 4-Sep-2019 22:38
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There are 8 French Doors, 1 entry door and 16 assorted windows.

 

Ah that may go some way to explaining the quote. All those French doors are going to be expensive. I'd assume the structural requirements may boost the gap between solid and thermally broken aluminium more than a window would. Every door requires double safety glass which pushes the costs up. So you have about 80m2 of glazing?

 

A thermally break shouldn't add 50% to the bill. Some other available thermally broken profiles will be cheaper than the Pacific Thermal Suit you were quoted for.

 

You don't have to get the same profile for all of the joinery. You could get thermally broken for the windows and front door and solid for the french doors. Or use a different supplier for the french doors.

 

The house is concrete block, filled with concrete in the voids, on solid concrete foundations. Roof is butynl over steel with pink batts but not to current specs probably.
Old ceiling pink batts may be only R1.5 with slumping. Are the concrete block walls uninsulated?

 

This PDFgives an idea of how thermally broken performs versus solid aluminium with plain and high quality low e glass. Plain glass lets in 1/3rd more solar heat gain than XCel/Planitherm XN although this can be a bad thing in summer if the glass cannot be shaded. Going from plain single glazing to plain double glazing can lead to greater overheating in summer while the lesser heat gain of low e glass makes for easier daytime cooling.

 

The performance of solid aluminium varies heavily depending on the quantity of exposed aluminium relative to glass so the R value of a small window is quite bad relative to a large window where the frame has less influence relative to the glass.

 

A U value of n means n number of watts is lost each hour per m2 per degree temperature differential. So a 3m2 window with a Uw value of 1.6 where it's 10c warmer inside than out means 48w is lost per hour. The R value is the inverse, so an R value of 2 is a U value of 0.5, an R value of 10 is a U value of 0.10 etc. A higher R value is better while a lower U value is better.

 

The "thermoplastic spacer" is inside the glazing unit between the glass panes. There are aluminium spacers but you don't want that in thermally broken aluminium as it forms a thermal bridge between inside and outside. Planitherm XN or "LightBridge" as they appear to be calling it now and be specified with either, but XCel always comes with the thermal spacer.

 

A recessed installation like they do in Europe should improve thermal break performance and condensation resistance, instructions for AllSeasons can be downloaded from here. Aluminium joinery in Australasia is normally installed around the exterior of the cladding. Other New Zealand thermally broken profiles can be installed recessed but I'm not aware of other brands providing instructions. APL Residential Thermal Heart should benefit the most from this as it's the narrowest thermally broken profile which while making it cheaper to make does make it more vulnerable to losing heat with the standard installation. The Omega thermally broken profile has been overtly designed to cope better with being installed on the exterior. Most New Zealand builders aren't going to be very good with non standard installs.

 

Assuming a well insulated house in a typical winter situation, I'd estimate solid aluminium with low e double glazing to be about 0.45c cooler for room temperatures than basic thermally broken with low e double glazing. PVC would be typically approximately 0,2c warmer than thermally broken aluminium however performance does vary between different products and there is some overlap (U1.3 best German TB alu, U1.4 weak PVC). European PVC has thicker frames and with solar insolation averaging as high as 1.8kW/m2/day in mid winter the effect of thicker frames mounts up. Slimline PVC frames are available but you lose out in other areas like longevity and presumably insulation. In mid winter where the windows have curtains in front of them for 14hr/day the quality of thermal drapes mitigates the differences between different windows. Real world with good low e double glazing could be under 0.1c advantage for PVC after reduced solar heat gain and thermal drapes are taken into account.

 

As much as PVC is marketed in New Zealand as a premium product, it's mostly used overseas because it's the cheapest option meaning its popularity would rapidly decline if it wasn't. Aluminium does need a thermal break to perform thermally but PVC needs metal to perform structurally (they are usually 20% steel by weight). Only fibreglass joinery doesn't need to be composited with another material to perform.

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  # 2310868 5-Sep-2019 08:27
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bfginger: As much as PVC is marketed in New Zealand as a premium product, it's mostly used overseas because it's the cheapest option meaning its popularity would rapidly decline if it wasn't. Aluminium does need a thermal break to perform thermally but PVC needs metal to perform structurally (they are usually 20% steel by weight). Only fibreglass joinery doesn't need to be composited with another material to perform.

 

Do you have a reference for that claim? This page shows uPVC as being more efficient than aluminium whether or not it's thermally broken, although there's not a heck of a lot in it - they're all fairly poor insulators.

 

PVC is heavily used in the coldest countries where they triple glaze. If aluminium was really better you think it would be used more, and if it's similar then you look at the other advantages and disadvantages. Aluminium might be a bit more durable, but not a lot, and it can be colored more easily.

 

PVC doors and windows are much cheaper overseas than in NZ. Much cheaper especially for standard sized doors, but unfortunately NZ loves custom houses / sizes so they might not fit.


 
 
 
 


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  # 2310951 5-Sep-2019 10:01
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Thermal efficiency is important but most people will be choosing PVC joinery because it has the lowest installed cost.

 

Likewise, most PVC use is driven by its lower price and not by its relative utility. Here's some indicative prices for the materials in USD/kg:

 

PVC 0.65
PE 0.70
PP 0.90
Steel 1.3
Aluminium 1.7

 

Yet PVC joinery doesn't usually have a lower lifetime cost so I would go for thermally-broken aluminium joinery, if I could afford it, because it also has other advantages that I want: longer life; stronger and more rigid; larger window area; better noise insulation; more easily recycled.

 

 

 

 


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  # 2310966 5-Sep-2019 10:04
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We are planning to retro-fit double glazing in our place in the near future, I am dreading the quotes as most of our windows are floor to what would be the ceiling if we had a ceiling.





Mike
Retired IT Manager. 
The views stated in my posts are my personal views and not that of any other organisation.

 

The is no planet B

 

 


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  # 2310994 5-Sep-2019 10:26
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Hammerer:

 

Thermal efficiency is important but most people will be choosing PVC joinery because it has the lowest installed cost.

 

Likewise, most PVC use is driven by its lower price and not by its relative utility. Here's some indicative prices for the materials in USD/kg:

 

PVC 0.65
PE 0.70
PP 0.90
Steel 1.3
Aluminium 1.7

 

Yet PVC joinery doesn't usually have a lower lifetime cost so I would go for thermally-broken aluminium joinery, if I could afford it, because it also has other advantages that I want: longer life; stronger and more rigid; larger window area; better noise insulation; more easily recycled.

 

 

PVC frames typically costs more than standard aluminium, but less than thermally broken aluminium. The raw material cost is only one factor in making a finished product.

 

 

 

MikeB4:

 

We are planning to retro-fit double glazing in our place in the near future, I am dreading the quotes as most of our windows are floor to what would be the ceiling if we had a ceiling.

 

 

Standard windows aren't too bad, glass and the framing isn't that expensive, it's doors that are really expensive. Yes huge windows will cost more than smaller windows of course. In a standard old NZ house I think PVC windows were about $15K installed (not including painting), one set of French doors $3K, single door $2K.


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  # 2311251 5-Sep-2019 14:38
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MikeB4:

 

We are planning to retro-fit double glazing in our place in the near future, I am dreading the quotes as most of our windows are floor to what would be the ceiling if we had a ceiling.

 

 

Unless you want better sound-proofing or you've got condensation problems that you can't solve some other way, or the existing window joinery is stuffed and needs to be replaced, then it might not be a good option anyway.

 

$30K plus is a hell of a lot of power you'd need to to save.  Based on our current heating cost, I'll be long gone before double-glazing had paid for itself. Solar PV and/or water would be a better way to reduce power cost for a lower outlay.

 

 




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  # 2311439 5-Sep-2019 19:34
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uPVC windows usually use more sophisticated hardware, which doesn't seem to be offered on aluminium frames.

 

 

 

I am thinking of the 'tilt and turn' system, which is really very good.






 
 
 
 




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  # 2311441 5-Sep-2019 19:39
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Ah that may go some way to explaining the quote. All those French doors are going to be expensive. I'd assume the structural requirements may boost the gap between solid and thermally broken aluminium more than a window would. Every door requires double safety glass which pushes the costs up. So you have about 80m2 of glazing?

 

 

 

A thermally break shouldn't add 50% to the bill. Some other available thermally broken profiles will be cheaper than the Pacific Thermal Suit you were quoted for.

 

 

 

You don't have to get the same profile for all of the joinery. You could get thermally broken for the windows and front door and solid for the french doors. Or use a different supplier for the french doors.

 

 

 

The house is concrete block, filled with concrete in the voids, on solid concrete foundations. Roof is butynl over steel with pink batts but not to current specs probably.

 

Old ceiling pink batts may be only R1.5 with slumping. Are the concrete block walls uninsulated?

 

 

 

The concrete has plaster outside, mass concrete and steel in the block voids and plaster inside. No specific insulation other than the aerated concrete in the blocks and air trapped in the voids if any.

 

 

 

This PDFgives an idea of how thermally broken performs versus solid aluminium with plain and high quality low e glass. Plain glass lets in 1/3rd more solar heat gain than XCel/Planitherm XN although this can be a bad thing in summer if the glass cannot be shaded. Going from plain single glazing to plain double glazing can lead to greater overheating in summer while the lesser heat gain of low e glass makes for easier daytime cooling.

 

 

 

That would be an issue here. Summer sun is harsh and there is no easy way to shade the windows due to placement of the building on the site without significant architectural enhancement.

 

 

 

The performance of solid aluminium varies heavily depending on the quantity of exposed aluminium relative to glass so the R value of a small window is quite bad relative to a large window where the frame has less influence relative to the glass.

 

 

 

A U value of n means n number of watts is lost each hour per m2 per degree temperature differential. So a 3m2 window with a Uw value of 1.6 where it's 10c warmer inside than out means 48w is lost per hour. The R value is the inverse, so an R value of 2 is a U value of 0.5, an R value of 10 is a U value of 0.10 etc. A higher R value is better while a lower U value is better.

 

 

 

The "thermoplastic spacer" is inside the glazing unit between the glass panes. There are aluminium spacers but you don't want that in thermally broken aluminium as it forms a thermal bridge between inside and outside. Planitherm XN or "LightBridge" as they appear to be calling it now and be specified with either, but XCel always comes with the thermal spacer.

 

 

 

A recessed installation like they do in Europe should improve thermal break performance and condensation resistance, instructions for AllSeasons can be downloaded from here. Aluminium joinery in Australasia is normally installed around the exterior of the cladding. Other New Zealand thermally broken profiles can be installed recessed but I'm not aware of other brands providing instructions. APL Residential Thermal Heart should benefit the most from this as it's the narrowest thermally broken profile which while making it cheaper to make does make it more vulnerable to losing heat with the standard installation. The Omega thermally broken profile has been overtly designed to cope better with being installed on the exterior. Most New Zealand builders aren't going to be very good with non standard installs.

 

 

 

Assuming a well insulated house in a typical winter situation, I'd estimate solid aluminium with low e double glazing to be about 0.45c cooler for room temperatures than basic thermally broken with low e double glazing. PVC would be typically approximately 0,2c warmer than thermally broken aluminium however performance does vary between different products and there is some overlap (U1.3 best German TB alu, U1.4 weak PVC). European PVC has thicker frames and with solar insolation averaging as high as 1.8kW/m2/day in mid winter the effect of thicker frames mounts up. Slimline PVC frames are available but you lose out in other areas like longevity and presumably insulation. In mid winter where the windows have curtains in front of them for 14hr/day the quality of thermal drapes mitigates the differences between different windows. Real world with good low e double glazing could be under 0.1c advantage for PVC after reduced solar heat gain and thermal drapes are taken into account.

 

 

 

As much as PVC is marketed in New Zealand as a premium product, it's mostly used overseas because it's the cheapest option meaning its popularity would rapidly decline if it wasn't. Aluminium does need a thermal break to perform thermally but PVC needs metal to perform structurally (they are usually 20% steel by weight). Only fibreglass joinery doesn't need to be composited with another material to perform.








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  # 2311442 5-Sep-2019 19:42
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As an aside, we did have architects draw up plans to renovate the house with a new German roofing system (shallow pitch), additional patio shading and some stone cladding on pillars. Also to move the existing car port and create a garage/porch area instead.

 

The windows etc were within that job.

 

 

 

It got scaled back (drastically!) when the only local firm I would have trusted to do it quoted....$750,000 inc GST.

 

 

 

I pointed out it would have been cheaper to bulldoze the house and just put a new one on the site!






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  # 2311770 6-Sep-2019 14:13
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@bfginger do you agree with @Disrespective that thermally broken joinery is essentially pointless if the windows is installed outside if the thermal line of the wall?

 

We are in the process of planning our build, and I assume our windows will be installed in the "standard NZ way" which sounds like is generally outside the thermal line of the wall.

 

The additional cost to go thermally broken would be $4500 for our build (so nowhere near as much as the OP).

 

EDIT: Would thermally broken also be pointless if you went with something like Low E Plus that doesn't use a thermal spacer?

 

 


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  # 2311856 6-Sep-2019 16:44
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for that small outlay compared to the OP's i would do it.


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  # 2311935 6-Sep-2019 18:45
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Geektastic:

As an aside, we did have architects draw up plans to renovate the house with a new German roofing system (shallow pitch), additional patio shading and some stone cladding on pillars. Also to move the existing car port and create a garage/porch area instead.

 

 

I was impressed at the amount of German, or more generically European, stuff you can now get here, tilt-and-turn windows on show at the Auckland home show, and Ytong blocks, which I'm really tempted to use in the upcomng reno of the Casa de Cowboy. Both of these are bog-standard for building in Europe, but until now I've never seen them in NZ. For people not familiar with the blocks, they're thermally-insulating foamed concrete, so a means of using concrete blocks to build a warm basement instead of a cold one.



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  # 2311938 6-Sep-2019 19:00
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neb:
Geektastic:

As an aside, we did have architects draw up plans to renovate the house with a new German roofing system (shallow pitch), additional patio shading and some stone cladding on pillars. Also to move the existing car port and create a garage/porch area instead.



I was impressed at the amount of German, or more generically European, stuff you can now get here, tilt-and-turn windows on show at the Auckland home show, and Ytong blocks, which I'm really tempted to use in the upcomng reno of the Casa de Cowboy. Both of these are bog-standard for building in Europe, but until now I've never seen them in NZ. For people not familiar with the blocks, they're thermally-insulating foamed concrete, so a means of using concrete blocks to build a warm basement instead of a cold one.


Eventually everything gets here...🤣





neb

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  # 2311961 6-Sep-2019 19:40
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Geektastic: Eventually everything gets here...🤣

 

 

My one concern with the Ytong blocks is that since they're little-used here I may run into both regulatory problems (the council doesn't know how to deal with them) and building problems (the builder doesn't know how to deal with them). I'll post updates as/if things progress.



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  # 2311987 6-Sep-2019 21:27
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neb:
Geektastic: Eventually everything gets here...🤣


My one concern with the Ytong blocks is that since they're little-used here I may run into both regulatory problems (the council doesn't know how to deal with them) and building problems (the builder doesn't know how to deal with them). I'll post updates as/if things progress.


Agreed.

I'd like to see a bit of out of the box thinking on the regulatory side.

Many of these materials have been tested in labs like Germany's TUV or the UK's BRE.

Likewise many are tested in places with very similar challenges such as California.

There must be a way too use them that does not require a whole set of new tests. NZ isn't that special.






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