Window Types

Frame and glass types

Note: The following table showing the frame and glass types in BASIX applies only to certificates generated prior to 1 July 2017, or revision of those certificates if validly lodged with the consent authority.

The U-value column represents the heat loss/heat gain of the system (frame + glass). The lower the U-value the better the glass will resist heat flow in and out of the window.

The Solar Heat Gain Coefficient (SHGC) column represents the ability of the system to reduce solar heat gain. Selecting a low SHGC system will reduce your cooling loads but will also cut out some solar gain and may therefore increase your heating loads depending on the orientation, shading and climate zone.


Frame and glass 



standard aluminium, single clear



improved aluminium, single clear



standard aluminium, single toned

7.57 0.57

improved aluminium, single toned

6.39 0.56

standard aluminium, single pyrolytic low-e

5.70 0.47

improved aluminium, single pyrolytic low-e

4.48 0.46

standard aluminium, double clear

5.34 0.67

improved aluminium imp., double clear

4.12 0.66

standard aluminium imp., toned/air gap/clear                      

5.31 0.48

improved aluminium, tned/air gap/clear

4.09 0.47

timber or uPVC, single clear

5.71 0.66

timber or uPVC, single toned

5.67 0.49

timber or uPVC, single pyrolytic low-e

3.99 0.40

timber or uPVC, clear/air gap/clear

3.67 0.59

timber or uPVC, toned/air gap/clear

3.64 0.42

What is an 'improved aluminium' frame?

The distinction between a standard and improved aluminium frame is performance based - i.e. improved frames have a lower U-value. This distinction allows window manufacturers to have products that meet the U-value criteria with a range of design and construction options. Many popular aluminium windows will meet the improved performance level. Selecting an improved aluminium frame will improve your heating load without increasing costs because that is what you are likely to be buying anyway. You will need to provide certification of the U-value and SHGC, which is readily available from these manufacturers.

Certifying the windows and glazed doors in your dwelling

The BASIX Certificate will display the U-value and SHGC for the frame and glass types that you have selected.

For standard aluminium and standard timber/uPVC frames with clear or toned glass, you are not required to provide certification of the U-value and SHGC of the windows installed in your dwelling, although the description must match. This is to allow for worst case aluminium windows and handmade timber windows that often are not tested. This policy is likely to change in the futures as the industry becomes more familiar with certification of windows.

For all other frame and glass types:

  • The U-value of the window or glazed door you select must be lower than the value shown
  • The SHGC of the window or glazed door you select must be +/- 10% of the value shown.
  • The description is included as a reminder of the type you selected. It is not mandatory to match the description (refer below) and is not sufficient on its own. For these types, you must provide certification of the U-value and SHGC under NFRC conditions (refer below).

Frame and glass type not in the list?

You can still use another system if you know its U-value and SHGC even if the description does not match. Select the system in the list that has a U-value higher than your type and within 10% of the SHGC of your type.

If you have single sheet obscure glass, select 'single toned' with the appropriate frame.

If you are using glass bricks, select 'double clear' with improved aluminium frame.