Cooling Off Period
Sydney Morning Herald
Thursday January 16, 1997
Traditionally, Australians are as bad with summer as we are with winter. We just grit our teeth and wait it out. But there's no reason to. Staying cool is a breeze.
THE temperature has been in the high 30s for nearly a week. Your home is so stiflingly hot that you begin to relish going to work, to the supermarket; anywhere that offers a little air-conditioned relief.
As you toss and turn during yet another fitful night's sleep in your airless bedroom, you make a resolution. By next summer, your home will be supercool.
The good news is that creating a cool living environment need not cost a fortune - particularly if you're about to build or renovate. And there's a bonus: the features that keep a home cool in summer will also help to keep it warm in winter.
The keys to low-cost cool living are excluding the fierce summer sun and preventing the warmer outside air from getting indoors. Succeed on both those fronts and, according to energy expert Max Mosher, many Syd-neysiders will need no more than a ceiling fan to keep them cool. Fail and they will almost certainly have to resort to more drastic - and expensive - measures.
"Keeping the sun off the glass is probably the biggest key to providing summer comfort," says Mosher, who points out that sun is radiated through glass at the rate of 1,000 watts a square metre - and that sun streaming through an average-sized bedroom window is equivalent to having an electric heater on its highest setting.
The best way to keep the sun out is with external blinds, eaves or a veranda that will cast a shadow on the glass and keep out 90 per cent of the heat. Window tints keep out 60 per cent and curtains or internal blinds 50 per cent.
Good insulation is important because heat naturally flows from a warmer place to a cooler one. A typical uninsulated brick-veneer house will admit 30 per cent of heat through the roof, 20 per cent through the walls, 20 per cent through the floor, 15 per cent through glazing and 15 per cent through draughts.
Insulating the ceiling and walls, carpeting the floor and fitting heavy curtains or double glazing could reduce heat transfer by a half to two-thirds - and will make a house much cosier in winter, when heat escapes from the same places.
Both Mosher, project officer of the Department of Energy's nationwide house energy rating scheme, and architect Eve Laron, who specialises in solar design, stress that cool living begins at the drawing board (see New- house planning).
But if your home breaks all the rules - as, they lament, most do - there is still much that can be done to make it more comfortable (see Renovation tips).
"You don't get perfection with renovation, but you do get enormous improvement," says Laron. "If you live close to the sea, you won't need air-conditioning at all. Elsewhere, your air-conditioning needs will be reduced by 75 per cent or more, your equipment will last forever and your power bills will be a fraction of what they used to be."
She cites a renovation she did on a Rose Bay home with westerly harbour views from the impossibly hot living room. By adding a big covered terrace that shielded the sun, but not the views, the room was transformed and the owners abandoned their plans to install air-conditioning.
Not all renovations produce such dramatic results, however, and for many homes some form of cooling system is the only solution. The options are:
REFRIGERATIVE AIR-CONDITIONERS
Heat is pumped from inside the home to outside (vice-versa in winter in the case of reverse-cycle models), air is circulated and humidity reduced. This makes them particularly suitable for Sydney conditions, although reverse-cycle models may freeze in cooler areas, such as the Blue Mountains. Types available include fixed room models that are fitted to an external wall or window, split systems that have the noisier compressor unit located outdoors, and ducted systems that cool a whole house.
Costs range from about $500 for a fixed room model to more than $5,000 for a ducted system. Portable models are available and can be hired - a good option when a family member is sick and feeling the heat.
WHOLE-HOUSE EXHAUST SYSTEMS
Fresh air is drawn into the home through partially open windows and hot, stale air is drawn into the roof and released outside through vents in the eaves. It costs about $2,500 to install, is more environmentally friendly and cheaper to run than air-conditioning and, says Mosher, often a good option for poorly designed houses, properties subject to heritage orders and top-floor units.
GEOTHERMAL HEAT PUMPS
These units pump warm air from the house into the ground (and from the ground into the house in winter) and provide water heating. They cost about 30 per cent more than a ducted refrigerative whole-house system, so are best considered when cooling, heating and water heating are needed. Mosher says they work best in areas with more extreme climates than Sydney's, such as the Blue Mountains and Southern Highlands.
EVAPORATIVE AIR COOLERS
These draw warm air over wet filter pads, where it evaporates, and work best in areas with low humidity. They cost from $200 for a portable model to more than $2,000 for a ducted whole-house system. Fixed room models are also available. Mosher does not recommend them for Sydney homes, but says they are ideal west of the Great Dividing Range.
Max Mosher and Eve Laron are among the speakers at a special Natural and Solar Design weekend this Saturday and Sunday at Sydney Building Information Centre, 525 Elizabeth St, Surry Hills, ph 9319 3000.
NEW-HOUSE PLANNING
Passive solar architecture was used by the ancient Greeks some 2,500 years ago and is the key to energy-efficient homes that are cool in summer and warm in winter.
Principles that will help keep your home cool include:
* Correct orientation. Full-length windows should be north-facing to take advantage of the low winter sun and have overhanging eaves, which keep out the higher summer sun. East- and west-facing windows should be kept to a minimum and be shaded in summer, preferably on the outside. The house should capture summer breezes.
* Good insulation. Heat moves from a hotter area to a colder one, unless there is a barrier. Key areas are the roof, walls, floor and windows.
* Clever landscaping. Deciduous trees are useful for providing summer shade and shrubs can help channel breezes into a house. Pergolas help shade a house, as well as providing a shady outdoor area.
RENOVATION TIPS
* If your renovations include an extension, ensure it is designed for maximum energy efficiency (see Cool design).
* If your living areas are badly oriented, consider changing the internal layout to provide north-facing living rooms.
* If your living areas face west to take advantage of a view, add a deep outdoor veranda that will provide shade without spoiling the view.
* Improve the insulation. Wall insulation is best incorporated at the building stage, but roof insulation, window coverings and carpets can be added at any time and will greatly reduce heat transfer.
* Keep the sun off windows, preferably from the outside.
* Install ceiling fans to improve ventilation and air flow.
* Choose white or pastel finishes that will reflect rather than absorb the heat.
© 1997 Sydney Morning Herald