Good orientation increases the energy efficiency of a home, making it more comfortable to live in and cheaper to run.
PRINCIPLES OF GOOD ORIENTATION
With good orientation the need for auxiliary heating and cooling is reduced, resulting in lower energy bills and reduced greenhouse emissions.
Choose a site or home with good orientation for your climatic and regional conditions. Build or renovate to maximise the site's potential and to achieve the best possible orientation for living areas.
In hot 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.
Where ideal orientation is not possible, as is often the case in higher density urban areas, an energy efficient home can still be achieved with careful attention to design.
[See: Passive Solar Heating; Passive Cooling]
Deciding the best orientation
Prioritise your heating and cooling needs. Are you in a climate that requires mainly passive heating, passive cooling, or a combination of both?
If unsure, compare your summer and winter energy bills, consult an architect or designer, or refer to local meteorological records. The website for the Australian Bureau of Meteorology is www.bom.gov.au.
[See: Passive Design Introduction]
Research of your local climate may include:
- Temperature ranges- both seasonal and diurnal.
- Humidity ranges.
- Direction of cooling breezes, hot winds, cold winds, wet winds.
- Seasonal characteristics.
- Impact of local geographic features on climatic conditions.
[See: Choosing a Site]
Observe the impact of adjacent buildings and existing landscape on your site.
Establish true or 'solar' north for your region. This is useful in all climates whether encouraging or excluding solar access. Maps and street directories can give this information. Alternatively, use a compass to establish magnetic north and then establish true or solar north by adding or subtracting the "magnetic variation" for your area using the map below.
Note that solar north deviates significantly from magnetic north throughout Australia and should be taken into account when orienting a home. All references to north in this guide are to solar north not magnetic north.
Your local council can assist you at the planning stage. Check the planning controls governing your site, for example building setbacks from boundaries and height limits, as they may affect how you build on your site.
ORIENTATION FOR PASSIVE HEATING
Orientation for passive heating is about using the sun as a source of free home heating. Put simply, it involves letting winter sun in and keeping unwanted summer sun out. This can be done with relative ease on northern elevations by using shading devices to exclude high angle summer sun and admit low angle winter sun.
'Solar access' is the term used to describe the amount of useful sunshine reaching the living spaces of a home. The desired amount of solar access varies with climate.
Various techniques are available for measuring solar access when designing a new home or renovating, to ensure good solar access without compromising that of neighbours. These techniques include computer programs, charts and formulas.
You can achieve good passive solar performance at minimal cost if your site has the right characteristics. Where possible, choose a site that can accommodate north-facing daytime living areas and outdoor spaces.
[See: Choosing a Site]
Sites running N-S are ideal because they receive good access to northern sun with minimum potential for overshadowing by neighbouring houses. In summer neighbouring houses provide protection from low east and west sun.
N-S sites on the north side of the street allow north facing living areas and gardens to be located at the rear of the house for privacy.
N-S sites on the south side of the street should be wide enough to accommodate an entry at the front as well as private north facing living areas. Set the house back to accommodate a north facing garden
Sites running E-W should be wide enough to accommodate north facing outdoor space. Overshadowing by neighbouring houses is more likely to occur on these sites.
A north facing slope increases the potential for access to northern sun and is ideal for higher housing densities. A south facing slope increases the potential for overshadowing.
Views to the north are an advantage, as north is the best direction to locate windows and living areas. If the view is to the south avoid large areas of glass in order to minimise winter heat loss. West or east facing glass areas will cause overheating in summer if not properly shaded.
On sites with poor orientation or limited solar access due to other constraints, an energy efficient home is still achievable through careful design. A larger budget may be required. Use of advanced glazing systems and shading can achieve net winter solar gains from windows facing almost any direction while limiting summer heat gain to a manageable level.
The ideal orientation for living areas is within the range 15°W-20°E of true or 'solar' north. (20°W- 30°E of true north is considered acceptable).
Poor orientation can exclude winter sun, and cause overheating in summer by allowing low angle east or west sun to strike glass surfaces.
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 the 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.