According to energy.gov.au, up to 40% of your home’s heat can be lost through your windows. One low-tech solution is to close your blinds or curtains (when it is colder outside than inside) which will help to reduce heat lost in this way. This should help to reduce the time you need to run your reverse-cycle AC or heater, and help to reduce heating costs.
More Household Hacks:
What costs less to run, a reverse-cycle air-conditioner or an electric heater?
How often do you clean the inside of your kettle? 😀