If you are going to get as much winter sun inside your house you want to minimise shading from neighbours and boundary fences/hedges.
Here is how to check…………………..
Ideally you should be aiming for around 6 of hours of sunlight on the shortest day (21st June). To get the exact angle for your location you can get solar calculators on the net that will give you the suns angle for every hour of the day for any day of the year.
I have provided a TABLE that shows approximate midwinter shade angles ‘A’, and shade slopes ‘H/D’ for various positions of latitude.
Here is an example of how to use the table for positioning a house in Melbourne in relation to a 1.8m fence as shown in the sketch above:
|Slope H/D||Angle||Slope H/D|
- The Bottom of the window is 0.15m above ground level
- The top of the fence ‘H’ is 1.65m above the bottom of the window(1.8m -0.15m)
- To make sure you get 6 hours winter sun in the window, divide the height of the fence above the bottom of the window by the ‘9.00am -3.00pm’ Slope (0.29).
- D = 1.65/0.29 = 5.7m. The fence needs to be 5.7m from the window for full sunlight for 6 hours.
- If the fence needs to be closer than 5.7m it worth checking if any sun gets to the bottom of the window. To check divide 1.65 by the ‘Noon’ Slope (0.57)
- D = 1.65/0.57 = 2.9m. If the fence is closer than 2.9m you may be better reducing the window size by raising the base.
This information also applies to Solar Panels for Heating and Power Generation
To provide summer shading see Shading Northern Windows