Cooling running costs

Family having a meal at the table in a large open-plan living area

The table below compares approximate annual running costs for various types of cooling systems for a range of room sizes.

Size of area cooled Cooler type Energy star rating Annual energy cost* Annual GHG emissions (kg)**
Room /Space cooling
Small room 12m2

Portable or ceiling fan N/A $5 15
Portable evaporative cooler N/A $5 20
Split system air conditioner
2.5 star rating $35 160
6 star rating $10 45
Medium room 30m2 Portable or ceiling fan N/A $10 35
Split system air conditioner 2.5 star rating $50 230
5 star rating $20 95
Large area 60m2 Portable or ceiling fans N/A $15 70
Split system air conditioner 2 star rating $75 355
3.5 star rating $45 210
Central cooling
Small house 100m2 Ducted refrigerative air conditioning – not zoned 1.5 star rating $195 925
3.5 star rating $80 380
Ducted refrigerative air conditioning – zoned*** 1.5 star rating $180 870
3.5 star rating $70 335
Ducted evaporative cooling Standard $45 205
Inverter $35 170
Ceiling fans N/A $25 115
Medium house 160m2 Ducted refrigerative air conditioning – not zoned 1.5 star rating  $255  1210
3.5 star rating $125 595
Ducted refrigerative air conditioning – zoned*** 1.5 star rating $235 1120
3.5 star rating $110 525
Ducted evaporative cooling Standard $65 295
Inverter $50 235
Ceiling fans N/A $40 180
Large house 220m2 Ducted refrigerative air conditioning – not zoned 1.5 star rating $315 1495
3.5 star rating $170 805
Ducted refrigerative air conditioning – zoned*** 1.5 star rating $285 1370
3.5 star rating $150 710
Ducted evaporative cooling Standard $80 385
Inverter $65 305
Ceiling fans N/A $55 250

* Approximate energy costs per year, rounded to nearest $5. Based an average existing (pre-2005) 2-Star house in a Melbourne climate, cooling all day on the weekend, and in the morning (midnight to 8am) and evenings (5pm to midnight) on weekdays when internal temperatures are high. Based on  an electricity tariff of 31.9 c/kWh. This is based on a typical Melbourne peak tariff, but does not include any pay on time discount. Note that the evaporative coolers will also use water, and the cost of the water is not included in this table. Actual costs for your house will depend on the area cooled, how long you run the cooling for, your thermostat settings, how well insulated and shaded the house is, your energy tariffs and your local climate. To estimate the running cost for a cold climate (e.g. Ballarat) multiply these figures by 0.85, and for a warm climate (e.g. Mildura) multiply these figures by 3.2. To estimate the running cost for a 5-Star house located in Melbourne, multiply these figures by 0.95, and for a 6-Star house multiply these figures by 0.85.
** GHG = Greenhouse Gas coefficient used is 1.18 kilograms of carbon dioxide equivalent emissions per kilowatt hour.
*** The figures for "zoned" operation assume that cooling in the bedroom areas is switched off during the day (8am to 5pm) and is only operated in the living rooms from 6am to 10pm when the house is occupied, e.g. on the weekends. On workdays, it is assumed that the cooling in the living rooms is only operated from 6am to 8am in the morning and from 5pm to 11pm at night. Other zoning arrangements are possible, and would change the saving achieved by zoning.

Use your cooling system efficiently

Remember, regardless of the type of air conditioner you have, if you operate and maintain your cooling system wisely you can reduce your cooling costs and still be comfortable.


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