Most people think double glazing is very expensive and it is true, it can be. When most people look at double glazing they get a glazier to quote. They normally won't fit double glazed units to existing windows but instead replace the whole frame, leading to a cost of around $800 per square meter, or $16,000 for a normal house with 20 sq metres of window. We reduce the price as follows:-
• If you have good quality wooden frames, you can use the existing frame. This halves the cost.
• We provide sufficient information to allow you to do the work yourself. While you need certain practical skills, equivalent to being able to construct a patio, it is well within the reach of the average DIY worker. This reduces the cost further to $4,000 a house.
We only provide double glazed units with argon rather than air in the gap. While this is slightly more expensive, it improves the window performance a further 6%.
As a good starting point, our base product (2 sheets of 4 mm glass) costs $175 per square metre.Most windows have a 12 mm gap (20 mm total thicknes). We can vary the gap from 6 to 16 mm for the same cost (14 mm to 24 mm total thickness).
We recommend the use of low-E glass for one of the panes of glass, especially on the south side of the house. It reduces the heat loss due to radiation by around 80%. Unfortunately, it also reduces solar transmission by around 10%. While this is good in summer it reduces heat gain from the sun in winter. In Victoria, the savings from reduced heat loss outweigh the reduced solar gain in winter. Since you get no solar gain on South facing windows, Low-E is ideal for these windows. A unit containing Low/E glass costs $245 per square metre.
If money is an issue, you are better to reduce the number of windows replaced, rather than compromising on Low-E glass. Replacing 3 windows with Low-E glass and leaving the fourth as a single pane of glass gives similar thermal performance as replacing all 4 windows with plain double glazing and the cost is around the same. It also means that you can return later and replace the fourth window.