This is one criteria and most commonly asked question among the home buyers – “is the facing of this unit affected by the heat from the afternoon sun?” Here is a crash course on how to determine if your dream home really has no west sun.
Due to the Earth’s tilt (a.k.a. Obliquity or axial tilt) of 23.5 degree (see diagram below), the sun does not set at the same position all year round. This is the reason why we say that the sun is up for half a year and disappear for the next half at the north and south poles of Earth. Furthermore, this obliquity is a very important reason that makes Earth the Earth you always know. Without it, there will be no four seasons on Earth. Before I go in deeper into the technical details, we just have to remember this magic angle of 23.5 degree.
Sunset Position/ View
I have met many home buyers who are delighted to tell me that they have just bought a perfectly north south-facing home with unblocked view that has no west sun as well. That is not entirely true as his family only get to enjoy half a year without the heat of west sun.
Referring to the diagrams below, due to the axial tilt, the sunset position moves between 246.5 to 293.5 degree throughout the year where it reaches the both extreme ends in mid June and mid December. The truth is – the sun only sets exactly at 270 degree West on 2 days of a year.
If you want to avoid the west sun heat totally, you will have to identify building features that can possibly block and cast a shadow on your unit during sunset. You can identify this by first checking if your block has exterior features that can block out the west sun such as staircase stack or shades design. Subsequently, you can look at your block / estate layout relative to the other adjacent buildings referencing to the west position to identify possible buildings that will cast a shadow at your property.
Otherwise, even the so-called best facing property has to endure the heat from the afternoon sun half of the time.
Finally, when your are viewing for your dream home, do remember to check your compass for the entire west sun range from 246.5 to 293.5 degree, or 23.5 to the left and right of the exact west direction.