Orientation and Shading

So how does it work

The key to designing a passive solar building is to best take advantage of the local climate. Passive design is design that does not require mechanical heating or cooling. Homes that are passively designed take advantage of natural climate to maintain thermal comfort.

During summer, direct sunlight produces around 1000watts /sq metre of heat energy onto every sq metre of the surface of our planet, whether it is a tree or a brick wall! This is the equivalent of a 2-bar radiator being directed at every sq metre of the external face of your home. Your roof, your walls, your doors and your windows. That is a lot of heat. It is easy to imagine how hot that will make your home in summer, yet in winter you want every bit of that energy, that sunlight, to heat your home.

Incorporating the principles of passive design in your home:

  • Significantly improves comfort
  • Reduces or eliminates heating and cooling bills
  • Reduces greenhouse gas emissions from heating, cooling, mechanical ventilation and lighting

Generally the ideal orientation for the home is with living areas and large windows facing north, minimal windows to the east and west. Windows to the south should be sufficient to allow for natural light and ventilation while minimising heat loss. The long axis of the home should normally be within 15° east or west of north. (You can go further than 15° from north if you give additional attention to shading.) Take into account buildings and trees that might reduce your solar access, and the direction of prevailing breezes. Drop by the Smart Living Centre and check out the model which shows how the Sun’s travel across the sky can affect a house. Shading systems can be used to moderate temperatures in buildings. For example, North facing windows can be shaded during summer to prevent excessive heating occurring in buildings. Shading systems are typically removable (or demountable) so that sunlight is used during cooler months for warming buildings. Some examples of shading systems commonly used are:

  • blinds and shutters
  • sails
  • louvres

 

Take Action

When buying

  • Choose a site with good orientation for your climatic and regional conditions. Be sure you can build to maximise the site’s potential and to achieve the best possible orientation for living areas.
  • Look for a home which has good orientation or can be easily adapted for better orientation.
  • Look for living spaces with good access to winter sun – North facing living areas and balconies or outdoor spaces are ideal.
  • Look for a suitable area of glass on north facing walls with access to winter sun. As a general guide this should be 10-25 percent of the floor area of the room.
  • Check that west facing glazing is not excessive in area and is properly shaded to prevent overheating. West facing walls receive the strongest sun at the hottest part of a summer day.
  • Check that there is no significant detrimental over-shadowing by adjacent buildings and trees.
  • Ensure that there is year round solar access for clothes drying and solar collectors.

When building

Build to maximise the site’s potential and to achieve the best possible orientation for living areas.

  • Design a home which has good orientation or can be easily adapted for better orientation.
  • Allow for living spaces with good access to winter sun – North facing living areas and balconies or outdoor spaces are best.
  • Install a suitable area of glass on north facing walls with access to winter sun. As a general guide this should be 10-25 percent of the floor area of the room.
  • West facing glazing should be minimal in area and properly shaded to prevent overheating. West facing walls receive the strongest sun at the hottest part of a summer day.
  • Ensure that there is no significant detrimental over-shadowing by adjacent buildings and trees.
  • Allow for year round solar access for clothes drying and solar collectors.

When renovating

Renovate to maximise the site’s potential and to achieve the best possible orientation for living areas.

It is important to discuss the project with competent designers to ensure that you can achieve what you want. The site and the existing dwelling will present challenges. The expertise and ideas that experienced “sustainable and solar efficient” architects provide is invaluable.

You are looking to get living spaces with good access to Winter sun, North-facing glass and year-round solar access. West and South-facing glass should be minimized, and the western aspect (including wall-space) should be well shaded from the afternoon sun in Summer.

More Information

Australian Government’s Your Home Manual explains the principles of passive solar design.