General information from Your Home and energy.gov.au, not design advice for a particular house. The official place to read more is Your Home’s passive cooling chapter.
Your Home explains it this way: “Sea breezes flow as the day’s heat warms the air further inland which rises, drawing in cooler air from the ocean. Common examples are the famous ‘Fremantle Doctor’ and the Sydney ‘nor-easter’.” Where a breeze like that is available, it says, “maximising their flow through a home is a key component of passive cooling.”
How far it reaches
Not every suburb gets the same breeze. Your Home says sea breezes “can be very localised, sometimes extending only a few hundred metres from the coast, but at other times extending hundreds of kilometres inland.” energy.gov.au’s guide for northern Australia notes that on the west coast, coastal breezes “are commonly south-westerly”, and that “Breeze direction can vary within a few 100 metres due to landforms, vegetation or buildings.”
Its advice for finding your own breeze is down to earth: “Talk to your neighbours in hotter seasons to establish the direction of your most reliable cooling breezes.” Wind records for major locations are kept by the Bureau of Meteorology.
A hot day, in order
Put together, energy.gov.au’s and Your Home’s advice makes a daily rhythm rather than a setting. Here it is as a sequence, each step in the sources’ words or close to them.
- As the day warms“Close windows, curtains, blinds, and doors during the hottest part of the day to block sunlight from entering your home.”
- Cooler outside than inYour Home’s advice: “create a cross-breeze by opening doors and windows on opposite sides of the building when the temperature outside is better than inside. Keep them closed when outside is hotter.”
- If the aircon is onKeep the house shut. Your Home warns that the “ventilation approach should not be used in conjunction with standard air-conditioning as you do not want to lose air that has been cooled.”
- OvernightClear skies help: Your Home explains that when the night sky is clear of cloud, air, ground and buildings radiate heat away, while “Cloudy skies at night hamper this effect.”
- Next morningenergy.gov.au’s northern Australia guide suggests a home weather station to help decide when to switch off and open up, and to “close up the next morning before the outdoor temperature rises.”
Letting it through the house
Your Home says cool breezes work best in buildings with narrow floor plans or open-plan layouts, and in places where windows can be left open: secure, quiet locations with good outdoor air quality. The garden can help steer it: “Design and locate planting, fences and outbuildings to funnel breezes into and through the building, filter stronger winds, and exclude adverse hot or cold winds.”
Where the breeze is weak, warm air can still leave by rising. Your Home describes stack ventilation, where “Even when there is no breeze, convection allows heat to leave a building via controllable openings such as high clerestory windows, roof ventilators or vented ridges.” It adds that convection usually moves air too slowly to cool people, which is where fans come in.
What the breeze crosses on its way in matters too. Your Home says gardens and green plants, rather than hard surfaces, help lower the temperature of air moving over them and around your home, and plants can shade and funnel cooling breezes.
Fans, the breeze you make yourself
“Fans do not cool the air or reduce humidity, but they do provide air movement which helps us feel cool.” Your Home says the airflow from a fan typically improves comfort about as much as lowering the temperature by around 3 °C, and that “Ceiling fans should be your first choice in keeping cool.”
Getting to sleep on a still night
Some nights the breeze drops before the house has cooled. Your Home describes a middle path between windows and machine: “running an air-conditioner in a closed room for about an hour at bedtime often lowers humidity levels to the point where air movement from ceiling fans can provide sufficient evaporative cooling to achieve and maintain sleeping comfort.” It also notes that in high humidity, low fan speeds are very effective.
Setting the house up for the afternoon
energy.gov.au’s northern Australia guide suggests keeping living areas and bedrooms away from the hot western afternoon sun, with a garage or bathroom better suited to that side of the house. If your air conditioner has an outdoor unit, it says to keep the area above it clear for airflow, and that adding shade can make overheating less likely.
The breeze will not reach every home, and on the hottest days it may not be enough. A licensed installer can look at where your house catches air and where a system would help most.