Efficient operation of the air conditioning system

The efficiency of an air conditioning system can be enhanced by taking the following approach before and during operation.

 Before turning air conditioning on:

1. In summer, open the windows and doors to allow breezes to travel through the home and expel as much hot air as possible. 

2. Try using ceiling fans, wall fans or pedestal fans whenever possible as an alternative to operating the air conditioning system in summer. Fans consume significantly less energy and will provide satisfactory comfort in many cases.

 When operating air conditioning:

  1. Close all external windows and doors.

2.   Close window blinds/curtains on hot summer days and cold winter nights, especially for windows facing east (in the morning) and west or north west (in the afternoon).

3.    Close internal doors, if possible, to separate areas that are occupied and require air conditioning from those that are unoccupied.

4.   When turning the air conditioning ‘on’, consider setting the ‘off’ time in advance.

 5.   Do not set the thermostat to a higher (or lower) temperature than is actually required (setting the thermostat lower in summer does not make the unit cool faster).

 Seasonal thermostat settings should be:

 1.    No less than 23 C during summer.

 2.    No more than 22 C in winter.

 3.     If the unit has adjustable blades to direct the airflow, direct them towards the ceiling when cooling (warm air rises), and towards the floor when heating (cool air falls).

 4.     If a hot day is expected, turn on the unit earlier in the day (as it operates more efficiently when the outside temperature is cooler) instead of waiting until later when the building becomes hotter.

 5.     Do not leave an air conditioner running if no one will be home for more than an hour as this will provide little benefit on return and can waste large amounts of energy while the home is unoccupied.

 6.     If a dwelling is to have air conditioning in an internal living area that is connected to an outdoor living area, owners should consider installing an automatic switching device to the doors leading to the outdoor living area. The switch could ensure the air conditioning unit switches off if the doors to the outdoor living area remain open for a set time (e.g. one minute), thereby reducing household energy consumption.

Maintenance of the air conditioning system

The maintenance procedure, including removing and cleaning/replacing the filter, should be outlined in the air conditioners instruction manual. It is recommended that the householder refer to this, or alternatively, contact an air conditioning professional.

The return air filter should be cleaned (or replaced depending on the model) at least every three months—as dirty filters can have impact on energy efficiency. This can be done by the householder.

Filters may be located in hinged filter frames attached to the return air grille, or in another position along the duct that returns air from the house to the air conditioner.

Some filters are not reusable and will need to be replaced each time, while others may be able to be cleaned with a cloth or rag and then washed in soapy water (be mindful to dry the filter properly before re-inserting into the air conditioner). Vacuuming certain filters may also be effective, although care needs to be taken because of the potential to damage the filter.

It is also generally recommended that an annual service be completed to maintain efficiency of the air conditioning system. This should be performed by a suitably qualified and licensed tradesperson, and includes:

  • A  basic check of the system’s operation including ‘air-on’ and ‘air-off’ temperatures
  • Cleaning of the return air filter.
  • Checking the level of refrigerant charge, for evidence of refrigerant leaks and ensuring correct operation of all fan motors and louvers.
  • Chemical cleaning of the indoor and outdoor heat exchanger coils if significantly blocked or dirty.


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