There are many types of glass technology available these days.
The bare minimum must comply with AS1288, but you may find your architect/builder has also specified a particular type of glass to be used. Likewise, if you need to get a 5 or 6 star energy rating, the type of glass you use will give you different results.
Glass affects not only heat transfer, but the amount of light that enters the house. Another important property of the glass is whether it is a safety glass or not. The location and use of the window/door will in many respects dictate what type of glass you should consider to use.
On a rough scale you have in terms of heat transfer;
- 3mm, 4mm, 5mm, 6mm float glass
- clear laminate glass,
- tinted laminate glass (grey)
- Low-E laminate glass (comfort plus etc)
- Double Glazed (insulated glass unit, IGU)
The good people at Chevron Glass have a handy chart for reviewing the performance of each type of glass. See below;
CHEVRON HIGH PERFORMANCE GLASS CHART
THE WINDOW MAN 
Just letting you know that the link to the Chevron Glass chart links to a page which is no longer available, cheers.
Hello X, thanks for letting me know -they must have changed their own site -. I’ve embedded the tech sheet in our page so you can now see the chart. regards PG – production manager of the window man.
I just phoned Chevron glass asking for this information, and they were unable to provide it to me. Thank you very much the window man, for having it on your site
haha im glad my little website can help you out JD. Weird they couldnt give you what i had up online…though its probably old now.
hopefully you can get the data you need from it. if you need something specific, and you cant find it – let me know, i have more bits n pieces in folders.
regards peter – production manager / bloke who runs the website
I could get exactly what i needed, thanks Peter – the 6.38mm grey has 42% light transmission, and the 6.38mm clear has 87%. The challenge i still have though, is whether to go double glazed clear, or double glazed with one of each.
almost ALWAYS it is – [grey 6.38 lam sheet (outside)] / [argon gap]/ [clear sheet.]
2 layers of grey lam is quite, quite dark.
same when doing obscure; [white translucent outside face] / [argon gap] / [clear (inside face)]