Natural air conditioner

Our tips for keeping your home cool this summer, using insulation and natural ventilation.
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02.Preventing heat gains

Heat always tries to move from warmer to colder areas - for example, in summer from the hot outside of your home to the cooler inside. By limiting the amount of heat that enters your home you may be able to get by without a cooling appliance. As well as making your home more comfortable to live in, this will keep your energy bill down.

Energy-efficient house design

  • If you're building or extensively renovating a house, the right design and materials can take advantage of the sun and prevailing winds to help regulate indoor temperatures. Ideally, the house will prevent or remove excessive heat gains in summer, while admitting and storing the sun's energy in winter.
  • The house should be elongated, with one of the long sides facing north.
  • Room temperatures will vary depending on how much they're exposed to sun and wind. For example, north-facing rooms will be the warmest rooms in winter and can get hot in summer. In most parts of Australia, living areas should face north (to take as much advantage as possible of the winter sun), bedrooms and studies east or west, and service rooms (such as the laundry) south.
  • Brick walls and a concrete floor slab can even out the temperature in north-facing rooms in summer, and store the sun's energy in winter to warm the house in the evening.
  • North-facing windows should be large; east, west and south-facing windows small.
  • Windows and doors should be aligned to allow cooling summer-evening breezes to flow through the house (cross-ventilation). Small windows in opposite walls are better than large windows in just one.


  • Insulated ceilings and walls reduce the heat flow between the outside and the inside of your home, keeping it warmer in winter and cooler in summer.
  • In summer, up to 35% of the heat in your house enters through an uninsulated ceiling, while 15% to 25% gets in through uninsulated walls.
  • Insulating the ceiling should be the number one priority for every house owner. However, to make the most of insulation in summer, it's essential you provide shading for east, north and west-facing windows. If you don't and the interior does heat up, the heat can't escape easily because of the insulation (the so-called oven effect). Your house may stay hot for a long time, even if outside temperatures drop.
  • Draught-proofing your home will also help keep the summer heat out. For example, close off unused pet doors and fireplaces, and seal windows with insulation strips.
  • See our insulation buying guide.


  • External shading (such as trees or bushes, eaves, awnings or shutters) is more efficient than internal (such as blinds or curtains) for preventing heat gains.
  • Shade all east, north and west-facing windows in summer, especially if your house is insulated.
  • While you should shade north-facing windows in summer, make sure they let in the winter sun. Deciduous trees are one way of achieving this: while their canopy provides shade in summer, they lose their leaves in winter. Artificial shading such as eaves, pergolas or adjustable blinds and shutters can do the same job.
  • East and west-facing windows should be shaded by vertical blinds or shutters, because eaves or pergolas won't block out the low morning and afternoon sun.


  • Air moving through your home will increase the evaporation of perspiration, making you feel cooler.
  • While you can use various appliances to create an artificial breeze, the right house design can take advantage of natural breezes.
  • Keep your windows shut during the day when it's hot, but open them in the evening once it's started to cool down.
  • Trees and bushes can help channel breezes towards your house.

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