climateXchange

That's interesting.

I'm not sure what happens with magnetite and wooden frames in Australia, Alec, as in my case the window frames are aluminium. So the only options were to either attach the magnetite directly to the glass or else to create a new frame with the magnetite that attaches to the existing aluminium frame.

Hi Alec, I think you can attach the magnets directly on the wood in Oz too.

In my case, I can now report the magnetite windows/doors have been installed and all look perfectly fine. It definitely feels cosier than before, but it's too early to judge whether it will reduce my gas heating bill significantly.

I checked gas usage for a 24 hour period before installation and two 24 hour periods after installation. One post-installation reading was higher than the pre-installation reading, and one was significantly less than the pre-installation reading, but I need to check the outside temperature on those respective days before I can reach a conclusion. In fact, I probably won't know for sure how much energy I'm saving until I receive my next gas bill.

The other thing I noticed was that cold air was coming in under the front door, and so despite past efforts to block drafts, clearly there is unfinished business there that could be undermining other measures such as doubleglazing. It just shows you that you have to look at the insulation of the house as a whole to make sure that each measure has maximum impact.

marea said:

Further to the problems with the drafts, I just found out today that my roof insulation has some major gaps due to poor installation by the installer  years ago and no doubt the house is losing heat that way.

So basically, the effectiveness of the double-glazed windows and the energy efficiency of the house overall are only as good as the weakest link.

I agree it is certainly worth checking that there are no gaps in insulation. However, the pedant in me wants to quibble about the 'weakest link' analogy. A chain is clearly only as good as the weakest link. In contrast, if you put super insulation into 3/4 of the area of your roof and left 1/4 uninsulated you would reduce the heat loss through your roof to almost a 1/4 of the loss through the previous uninsulated roof. That is not to say that it is not worth fixing the last few gaps in insulation but having some uninsulated areas is not nearly as bad as if you did not insulate at all. 

Similarly, if you have two windows and can double glaze one easily or cheaply but not the other, it is still worth doing the one you can do and almost halve your heat loss through the windows. 

Well, to add my voice to Marea on experience with Magnetite, in case others were interested. I have had a measure and quote for installation of two kinds of magnetite retrofitted double glazing (perspex) for small, medium and large aluminium sliding windows and one sliding door unit. The entire quote covers kitchen, loungeroom and 3 bedrooms. The dining room was already renovated some years ago with PVC double glazed units by another company, with which I've been very happy. Essentially, the windows left undone are in the bathrooms – but I'll get to those in a different way eventually.

Yesterday, I had a small window and sliding door in one bedroom, the kitchen and the large window in my living room installed. Some are in the form of units fitted directly on the glass, as that was the best way to conserve the window sill and enable the current sliding mechanism to function. I've noticed the living room heating does appear to be staying in the room more. The bedroom not so sure, but with minus 6.5 degrees this morning and no heating it seemed better than the minus 3 the morning before! The kind which is overlaid over the window in the reveal is quite nice, in fact it conceals the rather ugly aluminium quite well. In both cases (on glass and separate unit) none of it looks bad at all, I barely notice the difference visually, the perspex is perfectly clear. 

For all these various windows and doors the total quote came to just under $3000. If this improves the insulation in my place so the ambient temperature improves, I'll be happy, as that was much cheaper than replacing the whole lot. The business itself is super busy so I had the unhappy experience of having to reschedule for installation 3 times, but when the guy finally came around he was very pleasant and professional, arriving early, ringing me to finish, cut some keys for me and cleaned up entirely without leaving any mess behind!

And he pointed out that some drafts will limit effectiveness eg., drafts from freezing cold ensuite into bedroom under the door! Time to get some snakes.