We are replacing the windows in our house with double glazing.
At present, to do the job with Pacific Architectural frames and Low E Max sealed units with Argon the cost will be around $43,000 including GST for the windows supply and deliver only.
To upgrade the windows to thermally broken frames, it adds $15,000 + GST or thereabouts.
I have waded through screeds of information (unhelpfully, often presented in different formats or using different measurements etc) trying to calculate the cost/benefit of paying for the thermally broken frames. It is not an easy thing to do!
It seems that thermal breaking an aluminium frame will save you about 20% of the heat lost through the window. A window typically loses 10% of the heat lost from the house (I think) so you are looking at saving 20% of 10% - or 2% of the total.
Does anyone have experience of this? Does it sound about right? The glazing supplier is very much not what I would call a technical person and to be honest probably doesn't actually know how to make these calculations etc so his advice is a bit vague and generic.
There is a paucity of choice out here in terms of suppliers and, to be honest, most of them seem to get their stuff from the same place anyway, so shopping around is hard.