One of the first avenues we explored was the world of double glazing. There are alot of windows in the house all of fairly generous proportions. They are of timber construction and are double hung (sash). Most of them work with a few that need new sash cord or have minor cracked glass. They all sucked the cold air through the glass with gusto.
Coming from the UK Sean was very used to double glazing being the norm and not the unusual. Tasmania being of similar weather conditions to the South of England the thought was that double glazing might be more common than the rest of Australia. This was borne out by a quick scan of the Yellow Pages.
There are many frame materials used in double glazing; aluminium, timber, and uPVC are the most common. The thermal efficiency of windows and their frames are measured in U values. A very comprehensive explanation of windows and their properties, (including curtains and pelmets) is available here, http://www.yourhome.gov.au/passive-design/glazing in fact www.yourhome.gov.au is a great resource for all things in home renovation. The other places to check are the Window Energy Rating System (WERS) website and the Australian Window Association website. They have lots of information and links about windows and double glazing as well as the standards that window manufacturers need to meet.
Basically we arrived at the conclusion that aluminium framed windows, double glazed or not, were thermally very inefficient, timber frames are higher maintainence as they need regular painting or oiling so uPVC looked to be the way to go. uPVC is a material used extensively in Europe and the US.
In the North of Tasmania there are four suppliers/manufacturers of this type of window. Titane Windows (manufacturers uPVC), Launceston; Clark Windows, Smithton, Tas, 03 6452 2317; Certainteed WIndows, Martin Ruzicka, 0448 266 896.
We found out from Certainteed and then from Titane that they provide a unit replacement, which means that they only replace the windows and not the frames which in our case were timber. Only Certainteed made double hung units. Titane make an Austrian design of “tilt & turn” window. Both were ideally suited to our needs but at nearly $20,000 for the house was a budget breaker. As I was discussing this with the energy efficiency expert, Wayne Gorman, he mentioned that as the frames were timber they would have a fairly low U value (lower is better) and that you can get good results thermally wise from installing good quality thermal curtains and pelmets to create a still air space between the window and the curtains. (When we moved in there were only verticals).
The quote from Decorama Launceston, 43 Boland Street, LAUNCESTON TAS 7250 , Ph: (03) 63314949, for our curtains (full length to the floor), tracks, and all the curtain tape, hooks etc was only approx $3200. We will have to fit them and make the pelmets. The thought is now that we can always retrofit doubleglazing later on if we need to but the curtains are something that we would need anyway. Decorama took our order for the curtains at the beginning of October 2008.