Hey all, I'm new to this forum and hoping someone here has some info to help me out... I'm planning out a house build and it needs very good insulation for cold weather. At the same time I'm not made of money...
Just wondering if I need to significantly increase my wall insulation from R2.7 and what options are available that are cost comparable to a timber stud wall?
All other factors aside, are homes with high energy star ratings (over 7) fundamentally insulated differently to the traditional 2.7 bats in the walls and R6 in the roof?
Insulating 7 Start + new house
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Over insulating a poorly designed home is like putting a bandaid on a cut - best not to get cut in the first place. I hope the design of your house is making best use of the aspect (and I don’t mean view). That is the biggest factor of being able to achieve efficiency at a reasonable cost.
R2.8 of total wall insulation is more than enough even for much colder countries. For example, R3.6 wall insulation is a requirement for colder Arctic regions of Canada and Russia (however, still not high enough for Passivhaus). Also, the real insulation R is calculated a bit differently if you have some degree of insulated thermal mass integrated into your insulation system.
However, it is more important that this R2.8 insulation is consistent throughout the wall which is impossible to achieve with timber-framed houses + batts insulation set up as wooden frame will still be creating thermal bridging. For example, R2.7 in your energy rating calculations has nothing to do with reality, where your real insulation level will be most likely less than R2.0 if you have properly installed insulation and closer or below R1.0 if your insulation is not properly installed or you have issues with your waterproofing.
In addition, well insulated walls have to be also coming together with properly insulated windows, which is another issue, as even the best windows in Australia are hardly achieving R0.5 in insulation (U below 2.0), while e.g. Passivhaus standard requires windows to be insulated to R1.0+ or better (U values below 1.0). Such windows are not even supplied to Australia, while are relatively easy to get in Europe. E.g. I am ordering R1.5 windows (U value of <R0.7) to my house, which will work quite well with my consistent R2.8 wall insulation (without thermal bridging).
Another aspect - is a floor insulation, which is generally achieved by insulating under the slab as well as slab edge. You would also have to pay attention on how you connect internal and external slabs together to make sure there is no thermal bridging between those.
In addition to insulation, you would also have to consider proper use of house orientation, level of glazing, shading and especially thermal mass in your house.
Also remember, that heavily insulated tight house would also require a proper ventilation system to be installed and regularly used.
Hope it helps.
However, it is more important that this R2.8 insulation is consistent throughout the wall which is impossible to achieve with timber-framed houses + batts insulation set up as wooden frame will still be creating thermal bridging. For example, R2.7 in your energy rating calculations has nothing to do with reality, where your real insulation level will be most likely less than R2.0 if you have properly installed insulation and closer or below R1.0 if your insulation is not properly installed or you have issues with your waterproofing.
In addition, well insulated walls have to be also coming together with properly insulated windows, which is another issue, as even the best windows in Australia are hardly achieving R0.5 in insulation (U below 2.0), while e.g. Passivhaus standard requires windows to be insulated to R1.0+ or better (U values below 1.0). Such windows are not even supplied to Australia, while are relatively easy to get in Europe. E.g. I am ordering R1.5 windows (U value of <R0.7) to my house, which will work quite well with my consistent R2.8 wall insulation (without thermal bridging).
Another aspect - is a floor insulation, which is generally achieved by insulating under the slab as well as slab edge. You would also have to pay attention on how you connect internal and external slabs together to make sure there is no thermal bridging between those.
In addition to insulation, you would also have to consider proper use of house orientation, level of glazing, shading and especially thermal mass in your house.
Also remember, that heavily insulated tight house would also require a proper ventilation system to be installed and regularly used.
Hope it helps.
it is more important that this R2.8 insulation is consistent throughout the wall which is impossible to achieve with timber-framed houses + batts insulation set up as wooden frame will still be creating thermal bridging. For example, R2.7 in your energy rating calculations has nothing to do with reality, where your real insulation level will be most likely less than R2.0 if you have properly installed insulation and closer or below R1.0 if your insulation is not properly installed or you have issues with your waterproofing.
Thanks for this. Just regarding the thermal bridging... So you're saying that 90mm pine has lower R value than 90mm earthwoool bats?
Also I just saw in the yourhome.gov.au site that they recommend 2.8 minimum for the walls and 3.8 in alpine areas. Did I miss understand that? (http://www.yourhome.gov.au/passive-design/insulation)
it is more important that this R2.8 insulation is consistent throughout the wall which is impossible to achieve with timber-framed houses + batts insulation set up as wooden frame will still be creating thermal bridging. For example, R2.7 in your energy rating calculations has nothing to do with reality, where your real insulation level will be most likely less than R2.0 if you have properly installed insulation and closer or below R1.0 if your insulation is not properly installed or you have issues with your waterproofing.
Thanks for this. Just regarding the thermal bridging... So you're saying that 90mm pine has lower R value than 90mm earthwoool bats?
Also I just saw in the yourhome.gov.au site that they recommend 2.8 minimum for the walls and 3.8 in alpine areas. Did I miss understand that? (http://www.yourhome.gov.au/passive-design/insulation)
Correct. 90 mm pine will have up to 2 times lower R value than batts (can be even more, depending on the moisture level) and therefore, there will be thermal bridging effect. In addition, framing nails/screws will be also benefiting a lot to thermal bridging.
It is good to stay with recommendations, although expect that measured real life values will still be significantly lower.
E.g. check out Canadian insulation recommendations here (divide their R values by 5.68 to convert from imperial units to metric):
https://www.homedepot.ca/en/home/ideas- ... ation.html
As you can see that generally R3.3 of batts insulation + R0.9 rigid XPS board is good enough even for the Arctic
zone. XPS board is specifically used to reduce thermal bridging here.
Don't forget that in northern countries they were used to use a lot of insulated thermal mass in their wall systems and this thermal mass increases the real effect of the insulation.
Blardy cold winners here as far as I'm concerned.
Canberra
Blardy cold winners here as far as I'm concerned.
Blardy cold winners here as far as I'm concerned.
I know. We built down in the Monaro, where it is just a bit colder. If you are ever heading down this way you could drop in to see what I meant about designing the house for thermal comfort in the first place.
Ok so considering the timber in stud walls is rubbish for insulating, can anyone recommend a better, yet economical building material or cladding?
You can consider applying continuous blanket of insulation or rigid EPS/XPS insulating board to the front side of the studs.
Also, I have recently ran across this system, which combines cladding with insulation and can be attached to the studs, too:
https://www.smartstonesystems.com/
Also, I have recently ran across this system, which combines cladding with insulation and can be attached to the studs, too:
https://www.smartstonesystems.com/
We recently finished our own custom build in Canberra, which is performing well so far this winter (we've even had a couple of times where it's actually overheated and we've had to open lots of windows to cool it down). Part of our brief was to be highly energy-efficient while only using readily available (and affordable) materials and methods, and going for the best bang-for-buck (e.g. not going overboard to chase those last few percentage points of efficiency).
Our stud walls have R2.7 batt insulation - yes, batt insulation in stud walls isn't perfect, and shouldn't be relied upon as your only insulation layer, but it still definitely helps, and is one of the cheapest things you can do. The thermal bridging of the studs does mean that you need a second layer, though - for us, that's the 75mm EPS external cladding (NRG Greenboard cavity system, specifically). Windows are double-glazed uPVC with U-values of around 1.6-1.8 from a local supplier.
Our roof batts are R7.0 (the same caveats apply with roof insulation batts as with walls - it's not perfect and you'll have thermal bridging, but it's cheap and easy and still helps a lot), with an additional layer of R1.5 under the Colorbond roof.
Slab bottom and sides are also insulated with 50mm XPS. I strongly recommend (at least) slab-edge insulation in Canberra - it makes a noticeable difference. It's quite nice to be able to comfortably walk bare-footed on tiles in winter.
We also have a layer of vapour-permeable airtight building wrap (Bradford Proctorwrap) around the outside of the frame to minimise air leakage (no point in having good insulation if all your warm air just leaks out of the house - airtightness is one area where Australian houses are well behind international practice, and it makes a significant difference to both comfort and energy efficiency). We didn't go for Passivhaus levels of airtightness, but neither did we want the typical Australian leaky sieve. The Colorbond roof also helps with airtightness, as do some of the internal finishes (e.g. square set windows and ceilings have much less air leakage than architraves and cornices).
Most importantly, the house was designed with correct passive-solar orientation in mind, capturing a lot of direct Northern sunlight into the living areas, and minimising poorly-oriented windows (with compromises - for example, we have more westerly windows than ideal, in order to capture good westerly views).
The end result is a very energy efficient and comfortable house. Despite the larger size of the house, the official 'approval' energy rating was 7.3 stars - and that was before the windows were upgraded to uPVC, the roof insulation was upgraded from R6.0 batts to R7.0 plus R1.5 sislation, and the airtightness wrap and slab insulation were added - the 'as built' energy rating is closer to 8 stars (and we still haven't added window coverings yet). We could've done more, but we're at the point where doing anything further starts to cost quite a lot while improving performance only marginally. We feel that what we've done is well worth it for bang-for-the-buck; not only are our energy costs very low, but the house is much more comfortable to live in than most others (t-shirt weather inside during a Canberra winter with only minimal heating, while our poor neighbours are running their heating constantly and still have to rug up inside).
Cost-wise, the uPVC windows were the big-ticket item, adding about $12K over the quotes for 'standard' windows (you can see our build thread for how many windows we have). The airtightness wrap was only around $4K installed (including taping, although we didn't tape all the penetrations - again, bang-for-buck). The slab insulation was $3K - and in hindsight, I'd probably double it (100mm), especially around the slab edges. The EPS cladding was a little more expensive than bare brick veneer (although bricklaying prices are increasing), but cheaper than rendered brick - again, in hindsight, I'd consider increasing it to 100mm. The cost of upgrading the wall and ceiling batts was less than $2K.
If a cost compromise was needed, it'd be the windows - double-glazed (but still thermally-broken) frames from a major supplier would be cheaper, if slightly less effective. We wanted the better uPVC windows due to the amount of glazing we have, and we really love the tilt-and-turn mechanism - if you're not wedded to tilt-and-turn, and for a smaller house with fewer windows, the upgrade would be less attractive.
So, yes, you can readily achieve 7-8 star energy ratings in Canberra without breaking the bank, and without using any 'exotic' materials or construction techniques. But reiterating arcadelt's advice - start with the design first. Correct orientation and layout (yourhome.gov.au is a very useful resource) is actually a very significant factor, and (if done correctly) shouldn't cost you a cent.
Our stud walls have R2.7 batt insulation - yes, batt insulation in stud walls isn't perfect, and shouldn't be relied upon as your only insulation layer, but it still definitely helps, and is one of the cheapest things you can do. The thermal bridging of the studs does mean that you need a second layer, though - for us, that's the 75mm EPS external cladding (NRG Greenboard cavity system, specifically). Windows are double-glazed uPVC with U-values of around 1.6-1.8 from a local supplier.
Our roof batts are R7.0 (the same caveats apply with roof insulation batts as with walls - it's not perfect and you'll have thermal bridging, but it's cheap and easy and still helps a lot), with an additional layer of R1.5 under the Colorbond roof.
Slab bottom and sides are also insulated with 50mm XPS. I strongly recommend (at least) slab-edge insulation in Canberra - it makes a noticeable difference. It's quite nice to be able to comfortably walk bare-footed on tiles in winter.
We also have a layer of vapour-permeable airtight building wrap (Bradford Proctorwrap) around the outside of the frame to minimise air leakage (no point in having good insulation if all your warm air just leaks out of the house - airtightness is one area where Australian houses are well behind international practice, and it makes a significant difference to both comfort and energy efficiency). We didn't go for Passivhaus levels of airtightness, but neither did we want the typical Australian leaky sieve. The Colorbond roof also helps with airtightness, as do some of the internal finishes (e.g. square set windows and ceilings have much less air leakage than architraves and cornices).
Most importantly, the house was designed with correct passive-solar orientation in mind, capturing a lot of direct Northern sunlight into the living areas, and minimising poorly-oriented windows (with compromises - for example, we have more westerly windows than ideal, in order to capture good westerly views).
The end result is a very energy efficient and comfortable house. Despite the larger size of the house, the official 'approval' energy rating was 7.3 stars - and that was before the windows were upgraded to uPVC, the roof insulation was upgraded from R6.0 batts to R7.0 plus R1.5 sislation, and the airtightness wrap and slab insulation were added - the 'as built' energy rating is closer to 8 stars (and we still haven't added window coverings yet). We could've done more, but we're at the point where doing anything further starts to cost quite a lot while improving performance only marginally. We feel that what we've done is well worth it for bang-for-the-buck; not only are our energy costs very low, but the house is much more comfortable to live in than most others (t-shirt weather inside during a Canberra winter with only minimal heating, while our poor neighbours are running their heating constantly and still have to rug up inside).
Cost-wise, the uPVC windows were the big-ticket item, adding about $12K over the quotes for 'standard' windows (you can see our build thread for how many windows we have). The airtightness wrap was only around $4K installed (including taping, although we didn't tape all the penetrations - again, bang-for-buck). The slab insulation was $3K - and in hindsight, I'd probably double it (100mm), especially around the slab edges. The EPS cladding was a little more expensive than bare brick veneer (although bricklaying prices are increasing), but cheaper than rendered brick - again, in hindsight, I'd consider increasing it to 100mm. The cost of upgrading the wall and ceiling batts was less than $2K.
If a cost compromise was needed, it'd be the windows - double-glazed (but still thermally-broken) frames from a major supplier would be cheaper, if slightly less effective. We wanted the better uPVC windows due to the amount of glazing we have, and we really love the tilt-and-turn mechanism - if you're not wedded to tilt-and-turn, and for a smaller house with fewer windows, the upgrade would be less attractive.
So, yes, you can readily achieve 7-8 star energy ratings in Canberra without breaking the bank, and without using any 'exotic' materials or construction techniques. But reiterating arcadelt's advice - start with the design first. Correct orientation and layout (yourhome.gov.au is a very useful resource) is actually a very significant factor, and (if done correctly) shouldn't cost you a cent.
We recently finished our own custom build in Canberra, which is performing well so far this winter (we've even had a couple of times where it's actually overheated and we've had to open lots of windows to cool it down). Part of our brief was to be highly energy-efficient while only using readily available (and affordable) materials and methods, and going for the best bang-for-buck (e.g. not going overboard to chase those last few percentage points of efficiency).
Our stud walls have R2.7 batt insulation - yes, batt insulation in stud walls isn't perfect, and shouldn't be relied upon as your only insulation layer, but it still definitely helps, and is one of the cheapest things you can do. The thermal bridging of the studs does mean that you need a second layer, though - for us, that's the 75mm EPS external cladding (NRG Greenboard cavity system, specifically). Windows are double-glazed uPVC with U-values of around 1.6-1.8 from a local supplier.
Our roof batts are R7.0 (the same caveats apply with roof insulation batts as with walls - it's not perfect and you'll have thermal bridging, but it's cheap and easy and still helps a lot), with an additional layer of R1.5 under the Colorbond roof.
Slab bottom and sides are also insulated with 50mm XPS. I strongly recommend (at least) slab-edge insulation in Canberra - it makes a noticeable difference. It's quite nice to be able to comfortably walk bare-footed on tiles in winter.
We also have a layer of vapour-permeable airtight building wrap (Bradford Proctorwrap) around the outside of the frame to minimise air leakage (no point in having good insulation if all your warm air just leaks out of the house - airtightness is one area where Australian houses are well behind international practice, and it makes a significant difference to both comfort and energy efficiency). We didn't go for Passivhaus levels of airtightness, but neither did we want the typical Australian leaky sieve. The Colorbond roof also helps with airtightness, as do some of the internal finishes (e.g. square set windows and ceilings have much less air leakage than architraves and cornices).
Most importantly, the house was designed with correct passive-solar orientation in mind, capturing a lot of direct Northern sunlight into the living areas, and minimising poorly-oriented windows (with compromises - for example, we have more westerly windows than ideal, in order to capture good westerly views).
The end result is a very energy efficient and comfortable house. Despite the larger size of the house, the official 'approval' energy rating was 7.3 stars - and that was before the windows were upgraded to uPVC, the roof insulation was upgraded from R6.0 batts to R7.0 plus R1.5 sislation, and the airtightness wrap and slab insulation were added - the 'as built' energy rating is closer to 8 stars (and we still haven't added window coverings yet). We could've done more, but we're at the point where doing anything further starts to cost quite a lot while improving performance only marginally. We feel that what we've done is well worth it for bang-for-the-buck; not only are our energy costs very low, but the house is much more comfortable to live in than most others (t-shirt weather inside during a Canberra winter with only minimal heating, while our poor neighbours are running their heating constantly and still have to rug up inside).
Cost-wise, the uPVC windows were the big-ticket item, adding about $12K over the quotes for 'standard' windows (you can see our build thread for how many windows we have). The airtightness wrap was only around $4K installed (including taping, although we didn't tape all the penetrations - again, bang-for-buck). The slab insulation was $3K - and in hindsight, I'd probably double it (100mm), especially around the slab edges. The EPS cladding was a little more expensive than bare brick veneer (although bricklaying prices are increasing), but cheaper than rendered brick - again, in hindsight, I'd consider increasing it to 100mm. The cost of upgrading the wall and ceiling batts was less than $2K.
If a cost compromise was needed, it'd be the windows - double-glazed (but still thermally-broken) frames from a major supplier would be cheaper, if slightly less effective. We wanted the better uPVC windows due to the amount of glazing we have, and we really love the tilt-and-turn mechanism - if you're not wedded to tilt-and-turn, and for a smaller house with fewer windows, the upgrade would be less attractive.
So, yes, you can readily achieve 7-8 star energy ratings in Canberra without breaking the bank, and without using any 'exotic' materials or construction techniques. But reiterating arcadelt's advice - start with the design first. Correct orientation and layout (yourhome.gov.au is a very useful resource) is actually a very significant factor, and (if done correctly) shouldn't cost you a cent.
Our stud walls have R2.7 batt insulation - yes, batt insulation in stud walls isn't perfect, and shouldn't be relied upon as your only insulation layer, but it still definitely helps, and is one of the cheapest things you can do. The thermal bridging of the studs does mean that you need a second layer, though - for us, that's the 75mm EPS external cladding (NRG Greenboard cavity system, specifically). Windows are double-glazed uPVC with U-values of around 1.6-1.8 from a local supplier.
Our roof batts are R7.0 (the same caveats apply with roof insulation batts as with walls - it's not perfect and you'll have thermal bridging, but it's cheap and easy and still helps a lot), with an additional layer of R1.5 under the Colorbond roof.
Slab bottom and sides are also insulated with 50mm XPS. I strongly recommend (at least) slab-edge insulation in Canberra - it makes a noticeable difference. It's quite nice to be able to comfortably walk bare-footed on tiles in winter.
We also have a layer of vapour-permeable airtight building wrap (Bradford Proctorwrap) around the outside of the frame to minimise air leakage (no point in having good insulation if all your warm air just leaks out of the house - airtightness is one area where Australian houses are well behind international practice, and it makes a significant difference to both comfort and energy efficiency). We didn't go for Passivhaus levels of airtightness, but neither did we want the typical Australian leaky sieve. The Colorbond roof also helps with airtightness, as do some of the internal finishes (e.g. square set windows and ceilings have much less air leakage than architraves and cornices).
Most importantly, the house was designed with correct passive-solar orientation in mind, capturing a lot of direct Northern sunlight into the living areas, and minimising poorly-oriented windows (with compromises - for example, we have more westerly windows than ideal, in order to capture good westerly views).
The end result is a very energy efficient and comfortable house. Despite the larger size of the house, the official 'approval' energy rating was 7.3 stars - and that was before the windows were upgraded to uPVC, the roof insulation was upgraded from R6.0 batts to R7.0 plus R1.5 sislation, and the airtightness wrap and slab insulation were added - the 'as built' energy rating is closer to 8 stars (and we still haven't added window coverings yet). We could've done more, but we're at the point where doing anything further starts to cost quite a lot while improving performance only marginally. We feel that what we've done is well worth it for bang-for-the-buck; not only are our energy costs very low, but the house is much more comfortable to live in than most others (t-shirt weather inside during a Canberra winter with only minimal heating, while our poor neighbours are running their heating constantly and still have to rug up inside).
Cost-wise, the uPVC windows were the big-ticket item, adding about $12K over the quotes for 'standard' windows (you can see our build thread for how many windows we have). The airtightness wrap was only around $4K installed (including taping, although we didn't tape all the penetrations - again, bang-for-buck). The slab insulation was $3K - and in hindsight, I'd probably double it (100mm), especially around the slab edges. The EPS cladding was a little more expensive than bare brick veneer (although bricklaying prices are increasing), but cheaper than rendered brick - again, in hindsight, I'd consider increasing it to 100mm. The cost of upgrading the wall and ceiling batts was less than $2K.
If a cost compromise was needed, it'd be the windows - double-glazed (but still thermally-broken) frames from a major supplier would be cheaper, if slightly less effective. We wanted the better uPVC windows due to the amount of glazing we have, and we really love the tilt-and-turn mechanism - if you're not wedded to tilt-and-turn, and for a smaller house with fewer windows, the upgrade would be less attractive.
So, yes, you can readily achieve 7-8 star energy ratings in Canberra without breaking the bank, and without using any 'exotic' materials or construction techniques. But reiterating arcadelt's advice - start with the design first. Correct orientation and layout (yourhome.gov.au is a very useful resource) is actually a very significant factor, and (if done correctly) shouldn't cost you a cent.
For my 2 cents, I'm going to build b/veneer in Sydney and instead of using a single skin wrap, I'm going to use Kingspan's Air-cell Permicav XV. All the benefits of a normal wrap plus insulation over the studs.
Any chance you can explain further why you opted to use this product? Speed of construction?
I'm going to build b/veneer in Sydney
Also did you happen to get a power square metre rate to build the wall?
E.g. I am ordering R1.5 windows (U value of <R0.7) to my house, which will work quite well with my consistent R2.8 wall insulation (without thermal bridging).
alexp79 can you share where your windows are coming from, i.e brand and through whom did you order from?
E.g. I am ordering R1.5 windows (U value of <R0.7) to my house, which will work quite well with my consistent R2.8 wall insulation (without thermal bridging).
alexp79 can you share where your windows are coming from, i.e brand and through whom did you order from?
I am ordering Austrian Internorm windows from local distributor (PM me for the details) - tripple glazed KF500 secure profile, alum + PVC, U = 0.67 on average. Quite expensive - costs me approx. A$1.3K per sqm of glazing, but I believe it is really worth it, considering 10 year warranty, quality of the hardware and glazing, etc.
You can also consider German Dopfner windows from Laros: http://windows.laros.com.au/, they are a bit cheaper and they have timber + alum options, while U is a bit higher (0.8+).
E.g. I am ordering R1.5 windows (U value of <R0.7) to my house, which will work quite well with my consistent R2.8 wall insulation (without thermal bridging).
alexp79 can you share where your windows are coming from, i.e brand and through whom did you order from?
I am ordering Austrian Internorm windows from local distributor (PM me for the details) - tripple glazed KF500 secure profile, alum + PVC, U = 0.67 on average. Quite expensive - costs me approx. A$1.3K per sqm of glazing, but I believe it is really worth it, considering 10 year warranty, quality of the hardware and glazing, etc.
You can also consider German Dopfner windows from Laros: http://windows.laros.com.au/, they are a bit cheaper and they have timber + alum options, while U is a bit higher (0.8+).
Thanks for the reply. Will drop you a PM shortly. A$1.3K per sqm is reasonable considering it is triple glazed. Additionally Vitrocsa is about A$2.5K per sqm but that is the premium end of windows.
E.g. I am ordering R1.5 windows (U value of <R0.7) to my house, which will work quite well with my consistent R2.8 wall insulation (without thermal bridging).
alexp79 can you share where your windows are coming from, i.e brand and through whom did you order from?
I am ordering Austrian Internorm windows from local distributor (PM me for the details) - tripple glazed KF500 secure profile, alum + PVC, U = 0.67 on average. Quite expensive - costs me approx. A$1.3K per sqm of glazing, but I believe it is really worth it, considering 10 year warranty, quality of the hardware and glazing, etc.
You can also consider German Dopfner windows from Laros: http://windows.laros.com.au/, they are a bit cheaper and they have timber + alum options, while U is a bit higher (0.8+).
Be very careful comparing European U-Values, and Australian ones (ie WERS compliant). They are different, with the same window getting a lower rating in Europe than here (Europe assumes a larger window than Aus/US for the test, and so frames are proportionally smaller, and thus contribute less losses) - see http://www.paarhammer.com.au/blog/u-val ... australian
Also, when comparing other overseas markets, places like NZ often lists the glazing U value, not the glazing/frame U value (at least in marketing materials)
Be very careful comparing European U-Values, and Australian ones (ie WERS compliant). They are different, with the same window getting a lower rating in Europe than here (Europe assumes a larger window than Aus/US for the test, and so frames are proportionally smaller, and thus contribute less losses) - see http://www.paarhammer.com.au/blog/u-val ... australian
Also, when comparing other overseas markets, places like NZ often lists the glazing U value, not the glazing/frame U value (at least in marketing materials)
Also, when comparing other overseas markets, places like NZ often lists the glazing U value, not the glazing/frame U value (at least in marketing materials)
I agree, the difference will be there, but it won't be that significant. E.g. for a frame width of 80 mm, the Australian test window will have only around 7% of more frame when comparing to European test window.
For each window, I have U values provided for both glazing and frame+glazing.
Be very careful comparing European U-Values, and Australian ones (ie WERS compliant). They are different, with the same window getting a lower rating in Europe than here (Europe assumes a larger window than Aus/US for the test, and so frames are proportionally smaller, and thus contribute less losses) - see http://www.paarhammer.com.au/blog/u-val ... australian
Also, when comparing other overseas markets, places like NZ often lists the glazing U value, not the glazing/frame U value (at least in marketing materials)
Also, when comparing other overseas markets, places like NZ often lists the glazing U value, not the glazing/frame U value (at least in marketing materials)
I agree, the difference will be there, but it won't be that significant. E.g. for a frame width of 80 mm, the Australian test window will have only around 7% of more frame when comparing to European test window.
For each window, I have U values provided for both glazing and frame+glazing.
Not sure where your 7% comes from. Using your assumption of an 80mm frame, the Aus window (by area) is 66% glass, 34% frame. The European window is 78% glass, 22% frame. Now assuming the glass part is like some figures I have found for NZ triple glazed 46mm units (R1.81) that shows the frame is weak spot.
Now I am not saying your window choice isn't fantastic, but just be careful not to make a direct comparison of U value when they are not directly comparable.
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