Understanding the ‘sun-path’: Tips for natural solar design


The sun can have a massive impact on the comfort and energy efficiency of your home. Understanding the sun-path, and the location of your home and its design features relative to the sun, you can save on your power bill or even renovate to make your home lighter, brighter and more liveable. Dowell Windows explains how

What is the sun-path?

The easiest way to examine the movement of the sun relative to your property is through observation. Looking at the space around you for obstructions like trees, landforms or nearby buildings will also give you an idea of how your home’s aspect can affect solar access.

If you are looking for more information, using a sun-path diagram can help give you a wider understanding of how the sun travels through the day on any given area, as they show the direction of the sun at any time of day relative to your property. These can also be used to determine how shadows cast by obstructions can have an effect on the site.

When using a sun-path diagram, the centre is the point of observation. The adjacent arcs show the height of the sun at different times of the day, using a 24 hour clock. They are accurate to approximately 1 degree north or south of the allotted latitudes, however it is important to have accurate contour lines when using them.

Altitude and azimuth

The sun’s position relative to an observer is best described using two different angles – the altitude and the azimuth. The sun’s altitude is the angle of the sun’s rays compared to the horizon – at sunrise or sunset, the altitude is zero, and in the southern hemisphere, the maximum altitude of the sun at any specific location occurs at solar noon on 21/22 December, the two longest days of the year. Azimuth is the compass direction of the sun, and is also known as its bearing.

Solar energy: the sun-path’s power source

Solar radiation, also known as ultraviolet radiation (UV) is the energy that comes from the sun. Both the latitude and sunlight hours available determine how much solar radiation your property receives.

Shade is preferred in summer – due to the heat of most of Australia’s climate, however, in winter, sun is desirable to warm the home. Obstructions can have a seasonal impact on how much sunlight is received. It is also important if you are building your home to think about how obstructions may arise in the future. One example is a small tree on an adjacent site, which may grow into a big tree over time, or a building may arise on an adjacent site larger than the current one.

New build or renovation? Plan your windows according to your sun-path

Using web based tools to calculate the sun path can easily determine which window configuration would be most suitable on a particular side of the building. Resulting in a clever design combination of Dowell Thermaline™ and Dowell standard double glazed or single glazed windows to achieve maximum cost-energy efficiency building solution.

To see more projects and advice from Dowell Windows, visit their Complete Home  Company Profile

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