Natural air conditioner

Our tips for keeping your home cool this summer, using insulation and natural ventilation.
 
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03.Cooling appliances

Fans

Fans are cheaper to run and buy than evaporative coolers and air conditioners. However, they don't reduce the room's temperature, but influence how warm your skin feels: the air movement created by a fan increases the evaporation of perspiration, which makes you feel cooler.

  • Desk and pedestal fans can be plugged into normal power points. They're portable and - depending on the size - direct the air around either a person or a room. Prices start at less than $20.
  • Ceiling fans cost from about $60 (though are typically priced about $200 and up) and usually have to be installed by an electrician. They can improve the comfort of a room.

Evaporative coolers

These devices cool by evaporating water. A fan draws warm air from the outside through a series of wet filter pads. The air's heat evaporates the water, cooling and humidifying the air, which is then blown into the house. It's important to ensure good ventilation so the humid air doesn't accumulate inside.

The higher the outside humidity, the less efficiently evaporative coolers work, as the humid air from outside won't be able to evaporate much more water from the filter pads.

Size doesn't really matter. Of course, a larger, more powerful air cooler will have a stronger air flow and be able to blow cool air over a larger area; but essentially they don’t need to be matched to the size of the area like refrigerative air conditioners do.

Unlike air conditioners, you don’t have to seal the room or house. In fact, you need to keep a couple of windows or a window and door open because the cooler needs this air flow: it sits in front of an open window or external door and draws the outside air through it.

Don’t place the cooler in the middle of a room because it’ll just recycle its own moist air, adding more and more moisture. And make sure there aren’t any curtains close enough to be sucked into the unit.

They're cheap to run, but don't have a thermostat.

  • portable model plugs into a normal power point and is best placed close to an open window. Its water tank must be kept filled (as a rough guide, they use up to 4 L per hour). Look for a model with a water-level gauge, variable fan speed and adjustable louvres. Expect to pay from around $100.
  • A window-wall model is usually fitted into an external wall or window, and permanently connected to your power and water supply. Prices start at about $1000.
  • ducted system is permanently installed (usually in the roof) and ducted to ceiling outlets throughout the house. It uses about 25 L of water per hour, so may not be the right choice if your water supply is limited. A ducted system will cost from around $2000.

Note that evaporative coolers can only cool; they can't be made reverse-cycle like a refrigerative air conditioner.

Refrigerative air conditioners

Similar to fridges, refrigerative air conditioners pump heat from the hot inside of your home to the outside - that's why they're also called heat pumps.

They're very efficient, work in any climate, and are particularly useful in humid conditions, as they also dehumidify the air. Reverse-cycle models can also heat your home, because even cold winter air contains usable heat that can be pumped into your home.

Before you buy an air conditioner, it's important to know the size you need. As a rough estimate, you'll need a cooling capacity (or output) of about 125 watts per square metre for a living area, and about 80 watts per square metre for a bedroom. However, the ideal size depends on many factors, such as the climate where you live, your home's insulation and how well it's sealed, and the shape and orientation of the room.

Air conditioners are more expensive to run than fans and evaporative coolers. Domestic models carry an energy rating label: look for one with as many stars as possible - it'll save on your energy bill, and helps to protect the environment.

Also remember that each degree cooler you want your home in summer can increase the running costs by up to 15%.

Try to shade your air conditioner - for example, by providing an awning - without restricting its airflow. When you're expecting a hot day, turn it on early rather than wait until your home gets hot.

  • portable model can cool a room of up to about 20 square metres. It can be plugged into a normal power point. Expect to pay around $500 to $1300.
  • A window-wall model is usually installed in a window or external wall, and can cool rooms and open-plan areas of up to 50 square metres. While smaller units can be plugged into a normal power point, larger ones may require additional wiring. Prices start from under $500.
  • split-system air conditioner consists of a compressor unit that's installed outside, and one or more indoor air outlets. They're usually used to cool one or more rooms, or an open-plan area, of up to 60 square metres. Prices start from under $1000.
  • ducted system is usually installed in the roof or outside on the ground, and ducted to air outlets throughout the house. Costs start from around $5000.
 

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