The harsh sun in Australia, especially during the summer months, can make a home unbearably hot. One way to cool your home is with things like fans and air conditioners. Another more energy effective way to combat the heat is to keep the sun off it in the first place, using passive cooling strategies. A carefully placed pergola can do a great deal to shade the right parts of your home from the sun. How effective it is will come down to how much shade it's providing, and to which parts of your home.
Orientation, materials and colouring
The direction of the wall in relation to the sun will affect what type of shading and roofing you choose to use. A north facing wall, for instance, will see a lot of the sun, so may be an excellent candidate for shading - particularly if it's made of brick or something else with a high thermal mass. An east facing wall, on the other hand, may require much less shading as it will lose direct sun exposure at some point late in the morning.
Dark coloured walls and environments will attract more heat, and therefore require more shading than lighter coloured ones. If the walls of your house are dark, providing a bit of shade is likely to make a very significant difference to how hot your house gets.
Installing a pergola that uses the right types of vines or creepers to shade your windows and walls is particularly sensible. The advantage of using these planted screens is that they will self-regulate the temperature, allowing enough heat through in winter when they've lost their leaves, and absorbing it in summer when they're covered in foliage. Evergreen vines can be used in hot and humid climates, while in other climates it's best to opt for deciduous plants. It is worth noting though that vines and creepers can be home to certain insects, spiders and other sorts of life - a bit of homework before you choose a type of vine will help you to control or avoid this.
Pergola batten placement
For simple open roofed pergolas, clever placement of the battens can be an effective way to shade the house from sun at certain angles. By placing them close together and standing them up on their edges, they can create a louver-like effect, shielding underneath from the high angle sun and allowing light through when it is lower in the sky. The ideal size and spacing of the battens will depend on where you live, and how high the sun is in the sky at different times of the year.
Being able to change the slope of the roof of your pergola (or even open or close the roof as required) can be a huge advantage when regulating heat to your home. By constructing it in such a way as to allow you to prop the roof up on different angles or by installing a pergola with adjustable battens, you can use the sun to heat your home in winter and while still being able to shield it properly in summer.