Single glazing
IGU with 4 mm glass and 8 mm air space
IGU with 4 mm glass and 12 mm air space
IGU with 4 mm glass, 12 mm air space and low-e pane
IGU with 4 mm glass, 12 mm air space, low-e pane and argon gas fill
Aluminium R0.15 R0.25 R0.26 R0.31 R0.32
Thermally broken
R0.17 R0.30 R0.31 R0.39 R0.41
aluminium
Timber R0.19 R0.34 R0.36 R0.47 R0.51
uPVC R0.19 R0.34 R0.36 R0.47 R0.51
The actual Rwindow is dependent on the glazing, frame material and window size.
Source: NZS 4218:2009 Thermal insulation – Housing and small buildings (provided by Standards new