House and Garden

3 July 2012
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Cooling

73% of all homes in Australia have some form of cooling system. There are two main types - evaporative and reverse-cycle.

Evaporative Air Conditioning

This system consists of a box sitting on the roof which sucks outside air in through a number of vents. The air passes through pads which have water trickling through them. Some of the water evaporates, cooling the air which is then blown into the house through ducting and vents in the ceilings.

On the positive side, these systems are relatively cheap to run. On the negative side, in humid conditions the water does not evaporate easily and so the system does not work well. So it's not a good system for Brisbane or further north. Even in Perth, where they are popular, we get a few humid days each summer where these units are ineffective, and they're the very days when you really need cooling!

Reverse-Cycle Air Conditioning

The same system described under 'heating' can be used for cooling - it just runs things in reverse, thereby extracting heat from the indoor air and transferring it outside. The same options apply; either a ducted system blowing cool air through vents in the ceiling or split systems which blow cool air from a wall-mounted unit.

Fans

Although air-conditioning is popular in many areas of Australia, plenty of people manage to stay cool without it, by using fans - either ceiling fans or good old pedestal fans that you can buy for $20-$30.

Natural Cooling

If you don't have aircon, you will probably learn a few simple tricks to keep the house as cool as possible. The following applies to a Perth summer, but the principles will apply elsewhere, I am sure:
  1. Keep the sun out. Overnight, the interior of your house cools down, so it's a good idea to keep those tiles and walls as cool as possible by keeping the blinds or curtains closed if nobody is home during the day.
  2. Keep the easterly wind out. In Perth the strong easterly wind brings the hot air. Early in the morning it may feel cool, but it will quickly warm up, so it's best to keep it out of the house.
  3. Get the Fremantle Doctor in. Later in the day, the wind shifts round to the south-west - 'The Fremantle Doctor' - and is much cooler. The time this happens varies and sometimes it doesn't come at all. When it does, open up your windows and doors to get it through the house.