Free tool
Awning calculator
A good eave or awning keeps the high summer sun off your windows and lets the low winter sun in to warm the house for free. Put in your address and the size of your wall, and see where the sun lands in summer, spring and winter, at midday or any time of day.
1. Where is the window?
Type your NSW address, then tap the boundary your wall runs along on the lot plan.
Until you pick an address, the drawing shows a north facing window on the Central Coast.
2. Set the wall up like yours
Drag the round points, or type a size into any grey box on the drawing. All sizes are in millimetres.
NSW clock time, with daylight saving in December.
Or type the sizes here
3. What the midday sun does
Summer, 21 December
Sun 80° above the horizon at midday (12:52 pm).
Window in shade: 100%
No sun on the floor inside.
Spring, 21 September
Sun 56° above the horizon at midday (11:48 am).
Window in shade: 100%
No sun on the floor inside.
Winter, 21 June
Sun 33° above the horizon at midday (11:56 am).
Window in shade: 57%
Sun reaches 2.4 m across the floor.
The sun angles are worked out for your address on each date, at solar noon when the sun is highest, or at the time of day you pick. They allow for how far your wall turns away from north. A ray only reaches the room if it gets past the brick reveal (the depth of brickwork around the window opening) and the window frame to the glass.
More ways to keep your home comfortable
- Deck roof calculator: set the height and pitch of a deck roof so it shades the windows in summer and still lets the winter sun in.
- What is a north facing home?: why the north side of the house is where your living areas and big windows belong.
- Passive solar design principles: the guide to orientation, shading and thermal mass on the Central Coast.
- NSW Planning Portal: shading design principles: the guidance on shading windows for BASIX, the NSW sustainability rules for homes.
If you would like me to look at your windows and shading with you, book a free chat.
Questions people ask
How deep should an awning over a north facing window be?
Deep enough that the high summer sun stops on the wall above the glass, and no deeper, so the low winter sun still reaches in. On the Central Coast the midday sun is about 80° above the horizon on 21 December and about 33° on 21 June, so a modest awning or eave can do both. Put your sizes into the calculator and check that the 21 December line stops on the wall and the 21 June line reaches the glass.
Do awnings work on west facing windows?
Only partly. The afternoon sun on a west wall is low, so a fixed awning has to be very deep to stop it. Move the time of day to 4:00 pm to see it. Adjustable awnings, external blinds or vertical screens usually do better on the west.
Why is the sun angle on the drawing not the same as the sun's height?
The drawing is a section cut straight through the wall, and a shadow follows the sun's angle in that section. When the sun is off to one side of the window, that angle is steeper than the sun's real height, which is why a wall facing a little east or west of north is easier to shade at midday.
Does the calculator allow for where my house is?
Yes. Type your NSW address and pick the boundary your wall runs along. The calculator uses your latitude, the way the wall faces, and NSW clock time with daylight saving in December to work out where the sun lands.