Thermally Broken Aluminum Windows.

redmagic68

Hi All,

I'm just preparing to start a new build in North Leinster. We had hoped to use an Aluclad window but for budgetary reason our architect has suggested thermally broken aluminium windows. Having spent months researching Aluclad wondows i was happy they were the way to go. Could anyone give me info on the following.

1. Approximate cost compared to aluclad.
2. uValues compared to aluclad.
3. Problems with condensation.
4. Personal experience and advice.
5. Suppliers (please pm on this depending on mods).

Thanks in advance for the help people.

Captain Bluebear

Alu-clad frames are better insulated then thermally broken aluminium and timber looks and feels warmer internally.
There is a range of pricing for both types of system - you can get cheap and cheerful windows of either type.
As to condensation issues check out these youtube videos of composite windows - aluminium sash and timber frames;-
http://www.youtube.com/watch?v=_Id7SQHkF2k&feature=related
http://www.youtube.com/watch?v=R7g2p7i-f24&feature=related
http://www.youtube.com/watch?v=apxoGM0niTM

redmagic68

Captain Bluebear wrote: »

Alu-clad frames are better insulated then thermally broken aluminium and timber looks and feels warmer internally.

Thanks for the reply, i agree the aluclad system is best but with 104 spm of class i need a cheaper solution pvc for me is not an option. Just need to find a good aluminium window u value less than 1.5 preferable from a reputable supplier.

Captain Bluebear

Factor in how long you plan to live in the house you are building and how much heat you are going to be pumping out the windows over those years

With that much acerage of glass you should seriously consider triple glazing. Circa 40% less heat going out the window.

Whatever system you go with check out the pedigree and life expectency. No point putting something in that needs replacement in 15-20 years.

martinn123

Captain Bluebear wrote: »

With that much acerage of glass you should seriously consider triple glazing. Circa 40% less heat going out the window.

40% less heat loss, in another post you quoted 25%.

Mellor

Triple on the north facing at least.

heinbloed

martinn123 wrote: »

" .....40% less heat loss, in another post you quoted 25%. "

The actual savings or wastages of energy are depending not only on the material and workmanship but, since we look at a combination of heat transmission rates due to a mix of materials, on the size of the windows as well.

Using the same type of frame
a small window with triple glazing for example could save a higher percentage energy compared to a same size double glazed window.
But a larger triple glazed window (compared to a same sized double glazed window) migh save less percentage wise.

So (quoting the numbers of Captain Bluebear) 40% less heatloss might be achieved with a 1m2 triple glazed versus double glazed window but only 25 % with two triple glazed windows of 0.5m2 each.
If the frames insulate worse than the glazing.
The smaller the window the higher the frame ratio.

Included into the heatloss of the windows themself has to be the heatloss through reveals, lintels, cills. And through ventilation gaps sometimes found in window frames.
So many small windows could be more energy wasting than one large window of the same total surface.

The oposite could be the case if the frames where better insulating than the glazing.

For an exact thermal energy calculation regarding the windows most manufacturers will offer nowadays a detailed breakdown, some even include the solar gains into their calculation, the g-value.
The more details are fed into the energetic calculation the more compareable, relyable the results will be.
Detailed calculation programs can be downloaded from the internet.
The PH certified manufacturers offer these calculations as standard sales practice, check their home pages. Others do so as well. But some don't, one has difficulties to get any numbers from them exept from what it says on the bill.

Captain Bluebear

martinn123 wrote: »

40% less heat loss, in another post you quoted 25%.

There are numerous options with triple glazing. In the other thread you were talking about some rubbish with a u-value of 1.1. There are glazing units readily avilable that can comfortably get to 0.6 or even 0.5 without using Krypton. Commonplace for continental european suppliers. Unfortunately not so for our own manufacturers.