Window orientation and placement

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Good house and window orientation increases the energy efficiency of a home, making it more comfortable to live in and cheaper to run. The most important orientation aspect to consider is the direction your house and windows face and their solar access.

In high humid climates and hot dry climates with no winter heating requirements, orientation should aim to exclude sun year round and maximise exposure to cooling breezes. In all other climates a combination of passive solar heating and passive cooling is required. The optimum degree of solar access and the need to capture cooling breezes will vary with climate.

Angle of the sun in summer and winter. 
Angle of the sun in summer and winter.

It’s important to design your home for the entire year, not just one season. The ideal house orientation is one that runs along an East-West axis so that wall areas receiving hot morning and afternoon sun are minimised. Also take into account the location of landscape features such as trees and walls and their impact on solar access.

The amount of sunlight directed at a window varies according to the time of year, housing density and orientation. In the southern hemisphere the angle of the sun makes a low arc across the sky in winter with its highest arc reached in Summer.

North-facing windows receive twice the winter sun than east and west facing windows, allowing light and warmth into the home. They can be easily shaded from the high summer sun to help keep the house cool. Ideally, the glazing area should be between 10-25% of the floor area of the room.

Tip       
  • Locate common rooms such as your living, dining and kitchen to the north.
  • Keep eaves to a depth of 600mm so they don’t block winter sun.

East and west-facing windows receive little sunlight in winter, autumn and spring, but excessive sunlight in summer. It is recommended windows are kept small and well-shaded, particularly those facing west if this does not compromise ventilation. Alternatively, consider using high performance glazing such as low-e or toned glass.

Tip       
  • Consider locating your garage to the west side of your home.
  • Use smaller, well-shaded windows to reduce heat gain or use high performance glazing.

South facing windows receive no direct sunlight in winter and only early morning and late afternoon sunlight in summer. Windows should be kept small, however they can be extremely useful for passive cooling as part of cross ventilation as cooling breezes in summer usually come from the south.

South is a good direction for views as south facing windows require no shading from direct sun or minimal shading above the Tropic of Capricorn.

Tip       
  • South facing windows facilitate winter heat loss, consider double glazing to retain heat.
  • Keep windows small but openable to increase ventilation.

There are useful tools available to help you determine how the sun will affect your home based on your location, time of day and time of year:

 

Use high level windows and vents effectively in high density areas. 
Use high level windows and vents effectively in high density areas.

Dealing with poor solar access

 
Poor solar access can be detrimental to the comfort and energy performance of a home. Along with poor natural light levels, a lack of sunlight can make a home very cold - winter sun might be blocked by neighbouring buildings or views may be to the south or west, requiring windows with poor orientation. There are many innovative designs available to still achieve an energy efficient house. Selecting windows with improved thermal performance and high performance glazing is critical to compensate for poor orientation. The use of performance glazing can limit heat gain in winter and maximise heat gain in summer.

High density areas

When neighbouring buildings obscure wind and sun, there are a number of ways you can still achieve an energy efficient home.

  • Avoid full length windows as the lower part of the window will invariably be in permanent shade – raise the sill height to avoid heat loss through ‘wasted areas’.
  • Use high level windows and vents to create convection currents for cooling
  • Use insulation, draught proofing and window protection to improve the thermal performance where you are limited to solar access.
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