Aluminium suitable for windows ?

Hi

Aluminium alone in windows has a seriously limited life in the energy equation, every builder will remember - and contributed to - the shift from timber to aluminium over the past 5 years or so. The reasons were obvious - maintenance and cost. Today we have legislation and consumer awareness pushing the energy effiiciency borders to new levels and as windowexpert says aluminium conducts heat really well (that's why we have aluminium cookware like frying pans ). So under pressure we are looking right now at the shift from a pure aluminium window to PVC and thermal break technologies and as an interim position, timber is making a comeback as a solution to aluminium's poor performance.

Every window manufacturer will shift their focus as they follow this trend. Most manufacturers are already developing the technology.

In the end the consumer will get a better product at a sensible price, it is inevitable.

So if you are thinking aluminium single glazed, think again - your supplier is already working on a better alternative. Don't put old technology into your family home or investment. Nobody cornered the market today in typewriters or sliderules.



Ed

Aluminium is a great material for windows:
* ultra low maintenance
* clean slim appearance
* can be made any colour or natural anodising
* If anodised, does not have to be recoated EVER

It's also an excellend thermal conductor. Aluminium is used for heatsinks because of this quality. So, use alumimium for your finishing surface, but never link the outside to the inside. That is, use thermally broken aluminium. Then you have the best of everything, unless you like the look of wood (and regular maintenance).

For those that are interested, thermal conductivity values for some materials (all values in W/m.C - the higher the number the more the thermal conductivity):

Aluminium: 220
Brick: 1
Cement: 0.3
Copper: 386
Glass: 1
Gold: 310
Iron: 72
Polystyrene expanded: 0.03
Porcelain: 1
PVC: 0.19
Silver: 429
Steel: 54
Wood: 0.15

So don't make your windows out of solid silver!

Cheers,
Casa

Yep I can vouch for this.
My place has the old aluminium sliding windows and the ali is freezing and it's actually warmer to touch the glass than the aluminium.
Don't go there.
Steve

Do they make stainless steel windows?

Ed,

Thermal conductivity is only one piece of the puzzle. Fortunatley, there are only three pieces to the puzzle for conductance (we won't even touch radiation and convection heat losses).

Heat loss = Conductivity * surface area / thickness

Therefore although aluminium is 220 times more conductive than glass, it is thicker(which is better) and has a smaller surface area.

If, for example, the aluminium frame surface area is 5% of the glass area and it's thickness is 10 times that of the glass, then the aluminium is 220*0.05/10 = 1.1. That is, you loose as much heat through the aluminium frame as you do through the glass. Very difficult to imporve the glass signifiantly. Changing from single pane to double glazed low emissivity only improves performance by 3 times, but thermally broken aluminium, PVC, wood, etc can give you about 100 times improvement.

I think I've rambles on...

Cheers,
Casa

P.S. Does anyone in Australia sell stainless steel frames or do you know a website.