Cooling your home
in Greener Homes on 7 February 2010
Choose cooling that won’t break the bank.
Summer hot spells not only induce BBQs and beach holidays, but also snap decisions to shell out for expensive air conditioners. Christopher Zinn from Choice argues that air con should be the last option, not the first. “People can – like lambs to the slaughter – be taken to very high energy use air conditioning systems. There are better, lower cost, lower impact options.”
In its ‘Your cooling options buying guide’ (available free online), Choice details a number of ways you can keep your home comfortable without purchasing a machine. The cheapest tactic is ventilation. Each evening, once the weather has cooled, open your windows to allow a cool cross breeze through your home.
To stop the heat entering to begin with, existing homes can be retrofitted with ceiling insulation, draught-stoppers and shading for north and west-facing windows. “Even if you have air conditioning, these things can substantially reduce your running costs,” Mr Zinn says.
For mechanical cooling, fans should be your first option. Phil Wilkinson, technical manager of the Australian Institute of Refrigeration, Air conditioning and Heating, says they’re a cheap and low-maintenance solution on days that aren’t super hot. “Fans create a draught that helps you feel comfortable as it moves across your skin, but they don’t lower the temperature.” Desk and pedestal fans start from about $20; ceiling fans, from $50.
Evaporative coolers are another lower-energy choice. They cool by drawing air through wet filters and then blowing it out. “The running costs are minimal because they only need to power a fan and a small water pump,” Mr Wilkinson says. They work best in warm, dry climates, so they’re well suited to Victorian summers.
Evaporative coolers come in portable, fixed or ducted systems and range in cost accordingly, from around $100 to over $2000. Be wary of their extra water use – the bigger the unit the more it will slurp. Portables can suck up four litres per hour and central units more than 25 litres.
Well-designed Australian homes shouldn’t require air conditioning, but if you can’t do without, be careful about what you buy. “Choose the smallest, most efficient unit to suit your day to day needs,” says Mr Wilkinson. Residential models are labelled with an energy efficiency rating. “Our advice is to look for as many stars as you can afford – the more stars, the less it costs to run.”
The institute has created Fair Air, an online guide to choosing the air conditioner that best suits you. Portable and fixed wall models begin at about $500; split systems, about $1000; and ducted systems, about $5000. Make sure you use a qualified installer (visit the ARCtick website for more information).
As with heating, it’s wise to zone your cooling to where you spend time, rather than chilling the whole home. Dress down and try setting the thermostat to between 25 and 27 degrees: each extra degree of cooling will increase energy consumption by up to 10 per cent.
Mr Wilkinson says regular maintenance is required to keep both air conditioners and evaporative coolers running well. “You have to clean the filters and heat exchange services and check anything that’s getting noisy. It’s the same as a car, you have to maintain them to keep their efficiency to a maximum, so refer to the manufacturer’s or the installer’s advice.”