Compare approximate annual running costs for various types of cooling systems for a range of room sizes or for whole of house (central) cooling.
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The tables below compare approximate annual running costs for various types of cooling systems for a range of areas cooled in an average existing (pre 2005) house in a Melbourne (mild) climate and average cooling usage.
How we calculated the energy costs
* Energy cost and greenhouse calculations are based on average existing (pre-2005) house in a Melbourne (mild) climate and average cooling usage.
The energy calculations for refrigerative air conditioners and evaporative coolers use cooling load data from the 2020 Victorian Housing Stock Model, developed by Energy Efficient Strategies.
The energy performance of the refrigerative air conditioners is based on the cold climate energy rating and takes into account the spread of efficiencies of models registered for energy labelling in the different size ranges. It is assumed that houses that are larger than 100 m2 would use more than one multi-split air conditioning system to obtain a cooling service similar to ducted refrigerative cooling. It is assumed that portable evaporative coolers have an effective Energy Efficiency Ratio (EER) of 11, standard ducted evaporative coolers an EER of 15 and invertor ducted evaporative coolers an EER of 25. Estimated fan energy consumption has been obtained from the 2015 Space Conditioning Tool developed by Energy Efficient Strategies.Energy costs are based on an electricity tariff of 22.8 c/kWh. Note that the evaporative coolers will also use water, and the cost of the water is not included in this table. The 10-year greenhouse gas emission figures are based on the estimated average emissions coefficient for electricity in Victoria over the 10-year period from 2022, 0.578 kg/kWh. This is lower than the current emissions coefficient because the rapid increase in renewable electricity means that the emissions intensity of Victoria's electricity will reduce rapidly over the next decade. The actual costs and emissions for your house will depend on the floor area being cooled, how warm the house is when you switch on the cooling, how long you run the cooling for each day, 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 5-Star house (2006 to 2011) located in Melbourne, multiply these figures by 0.75, and for a 6-Star house (2012 to 2022) multiply these figures by 0.6. The cooling energy costs and emissions for a house located in a cold Victorian climate (e.g Ballarat) are about the same as for a house in Melbourne - these areas are inland and experience hot summers. To estimate the energy costs and emissions for a house located in a warm climate (e.g. Mildura) multiply these figures by 6 for a house constructed prior to 2005, and by 4 for a house constructed after 2005.
** GHG = Greenhouse Gas coefficient used is 0.578 kilograms of carbon dioxide equivalent emissions per kilowatt hour.
Remember, regardless of the type of cooling system you have, you can reduce your cooling costs and still be comfortable if you operate and maintain your cooling system wisely.