The change in sun angles over the year allows the shading
to be designed to allow sun to enter the building in
winter and be excluded in summer. In locations such
as Darwin, shading will be required for all times of the
year; in June, the sun will even hit a south‑facing wall if
shading is not provided.
Typical sun altitude angles at 12 midday for
northern facing walls for major Australian cities
The chart below provides a quick reference to
the appropriate eaves overhang. Sun control on the
east and west elevations of the building should also
be considered. Low-angle sun that hits the north and
east facade also needs consideration but is more
effectively controlled with vertical shades or external
shutters. The Eaves Overhang Chart below gives a
co-efficient of 0.95 for 1 May for Brisbane. This means
that a north‑facing wall 2.7 m high will need an eaves
overhang of at least 2.57 m to be shaded up until
1 May. Additional shading will be required for low‑angle
morning and afternoon sun.
North-facing window with height, H,
of 2100 mm located at 9 latitude.
What eave outstand, E, is required
to shade the window from 31 August
to 14 April?
From Chart, for 9 latitude, go to diagonal
line for the time of year (31 Aug/14 April)