Prepare before the evening
Limit direct sun using suitable existing coverings and reduce avoidable indoor heat where practical. Decide which room is the coolest usable space and whether there is a safe place to go if the home cannot be kept comfortable. Keep water accessible and follow personal medical advice where fluid intake is restricted. This guide is household planning, not individual medical advice.
Make ventilation conditional
Compare inside and outside conditions before opening up. Cooler outdoor air can be useful, but smoke, poor air quality, rain, pests and security may make open windows unsuitable. Keep child-safety devices and insect screens in mind. Cross-ventilation needs a path through the home; do not assume one small opening will reliably remove the heat stored in walls and furnishings.
Set up equipment for the actual sleeping space
Position a fan for the person without creating cable hazards, and follow its instructions for unattended use. A fan does not lower room temperature. For a portable AC, confirm exhaust sealing, condensate handling, noise at the intended mode and whether the window can remain secure. Do not move a unit into a closed room and leave its hot exhaust indoors.
Use timers without making a safety promise
A timer controls hours, not whether indoor conditions remain safe after switch-off. Try a schedule while awake and adjust to observed conditions. Use the cost calculators with your actual overnight rates rather than assuming all night-time electricity is cheap. If someone is unwell in the heat, follow Healthdirect guidance; suspected heatstroke or a life-threatening emergency requires triple zero (000). Cost saving must not delay help.
Common questions
Should windows always stay open overnight?
No. Temperature, humidity, smoke, weather, security and the occupants’ needs determine whether it is useful and safe.
Is a fan enough during severe heat?
Not necessarily. It does not refrigerate the room. Follow heat-health advice and arrange access to a cooler environment when needed.
Sources and scope
The following public Australian sources were read on 4 October 2026. Calculations and checklists are editorial work, not independent appliance tests. Local installation, rental and safety requirements vary; check the actual system and location.