Image
Top
Navigation
April 12, 2017

5 minute read

How are houses designed for the Australian Climate?

architecturally-designed-home

Australia is a large continent with a variety of climate zones. Under the National Building Code of Australia (B.C.A.) eight climate zones have been defined:

Climate zone 1 – High humidity summer, warm winter
Climate zone 2 – Warm humid summer, mild winter
Climate zone 3 – Hot dry summer, warm winter
Climate zone 4 – Hot dry summer, cool winter
Climate zone 5 – Warm temperate
Climate zone 6 – Mild temperate
Climate zone 7 – Cool temperate
Climate zone 8 – Alpine

Under each state’s legislation and the BCA, there are different construction requirements for each of these zones. There are also different planning strategies to be adopted for each zone.

Within NSW the main legislation impacting on house design is the Basix requirements.

The Basix legislation was introduced to address the issues of global warming by incorporating a reduction in energy usage and the reuse of stormwater in residential developments. Compliance with Basix requirements is part of mandatory government approvals which must be obtained for the construction of any house. The Basix requirements also vary according to the different climate zones within NSW.

The Basix requirements correspond with the design strategies which have been employed in architect-designed houses for a number of years. These broad principles include:

  • appropriate sun control
  • provision for natural ventilation
  • appropriate insulation levels etc.

When designing a house for the temperate climate zones of NSW, many of the strategies architects naturally incorporate will also ensure compliance with the Basix requirements.

The main principles for the Sydney, Central Coast and Newcastle areas can be summarised as follows;

 

Orientation

In Australia the continent is situated on the South side of the equator- the sun is in the Northern portion of the sky for the majority of the day. The most favourable sunny position is towards the North. Interior and outdoor living spaces should be positioned on the Northern side to enjoy the sunny and bright atmosphere.

On the eastern and western sides of a house, the sun is low in the morning and low in the afternoon. When the sun is low in the sky it is more difficult to control, particularly the setting western sun- which in summer can generate considerable heat.

Generally, the spaces on the southern side of a house tend to be colder and darker. When
planning for the Australian climate bedrooms and living spaces should be located on the
northern side of the house whilst ancillary spaces such as bathrooms, laundry, garages should be
located on the east and west or south sides.

Sun Control

Generally, the sun moves from east to west throughout the day- it’s higher in the sky during summer and lower in the sky during winter. When the sun is in the northern portion of the sky it can be easily controlled with horizontal projections or overhangs. A horizontal projection will enable the high Summer sun to be excluded, reducing heat gain and will allow the low winter sun to be admitted providing passive warming.

On the east and west sides of a building, the sun is generally lower on the horizon and alternative measures are required to control the sun. This can include adjustable louvres, fixed vertical louvres or adjustable fabric screens. Controlling the amount of direct sunlight entering the building plays a large part in the interior comfort conditions, preventing the building from being too cold in winter and too hot in summer.

Natural Ventilation

The promotion of natural ventilation is advantageous so we can enjoy the overall mild weather in the east coast. Natural cross ventilation is encouraged by considering the orientation of the house and by placing appropriate openings on opposite sides of the building. Consideration must be given to the prevailing breezes. In Newcastle and Sydney, the cooling North-East breezes are particularly beneficial in summer.

The owner must plan for the more unpleasant winds from the west and south which can bring colder weather with strong winds. The usual strategy is to restrict the openings on the west and south (subject to the orientation and surrounding terrain) and to provide more generous openings on the east and north. Internal walls forming the individual spaces should also be considered so airflow moving from one side of the house to the other is not restricted.

Insulation

It has been usual practice for many years to insulate the roof and the walls in architect-designed houses. With the introduction of Basix, the insulation of all building elements has received greater consideration. In constructing a house today the roof, ceiling, external walls, windows and floors are all assessed to meet the required insulation values. New and improved building products are continually being developed to provide more effective insulation.

With insulation materials such as building wrap (sisalation) and under floor linings are used to seal drafts- to prevent cold air from entering and warm heated air from escaping. Low energy glass or double glazing in windows is often used to increase the energy efficiency of the building. As preferences for larger windows and glazed sliding doors increases the insulation value of these openings becomes more important.

Our relatively benign climate allows for a year round indoor/outdoor lifestyle. In a typical suburban setting, the house is surrounded by lawns and gardens and often outdoor living areas. These exterior spaces can be used to modify the internal environment providing shade with pergolas and gardens shielding the house from the heat of the sun in summer. With correct design, these elements will still allow the low winter sun to filter through.

The majority of houses now incorporate open planning for living spaces- the open nature of these spaces aids in the promotion of cross ventilation. It also means heating or cooling can be achieved easily when compared to a number of small individual rooms where there is restricted circulation of air between each room.

These are general strategies to be taken into account when designing a home. With any general advice of this nature, the individual circumstances of each site and the actual orientation of the house must be taken into account. The relative importance of any one particular strategy will vary from house to house as these different site characteristics and orientation comes into play.

As architects, we can provide the appropriate advice and design in each circumstance to ensure the correct strategies are implemented to provide living conditions suitable to the owner’s comfort.

Contact Mark Lawler for more information on building the perfect Australian home.