Windows And Doors
Retrofit double glazing
In May 2007 I experimented with double glazing one of my south side (that's the cold side in New Zealand) windows. Here's what I did:
You need to specify the width and height (as per a normal sheet of glass, plus the size of the spacer. I had the options; 8, 10, 12, 14, 16, 18mm and so on up to 24mm (I think they went that far). I went for the 14mm - which resulted in an over all thickness of 23mm (4mm glass + 14mm spacer + 4mm glass + 1mm glue). That was about as thick as I could comfortably fit into the existing window frame.
What's the most efficient spacer to have? Here's a snippet from Wikipedia:
The gap is usually 12mm to 20mm thick. Within this range, the thickness does impact the insulating properties substantially, but smaller gaps have greater heat conduction through the air or other gas, and larger gaps allow more convection within the space leading to higher convective heat loss. A 16mm air gap is often considered the optimum thickness for air although this depends on many factors such as the size of the window, the temperature difference between the two panes and whether it is vertical.
I didn't go for low-E glazing - because it was almost twice the price.
Retrofit plastic acetate
I also experimented with cheap "window warmers" plastic double glazing. I bought a 3M 5 window kit:
You can buy it from: