Aircon running cost calculator

How to use this aircon electricity cost calculator

Enter one figure for your aircon, then how you use it and what you pay per kWh.

You can describe the aircon in one of two ways:

• Energy Label: the annual energy consumption in kWh printed on the label.
• Power input: the rated power input in watts, from the spec sheet or manual.

Then add the hours you run the aircon per day, the days you use it per month and your tariff in cents per kWh. The results show the energy used in kWh and the cost for each day of use, for a month and for a year (12 months).

Nothing you enter is stored or sent. To estimate other appliances, use the electricity cost calculator.

Where to find the figures

The National Environment Agency (NEA) Energy Label shows an aircon's annual energy consumption in kWh, the figure for the label method. For split and multi-split aircons, the label is affixed to the outdoor unit, and the model shown on it is the outdoor unit's model number. The label also shows the aircon's size as its full load cooling capacity in kW.

NEA's label scheme covers casement, window, split type (non-inverter), split type (inverter) and portable aircons, and rates efficiency from 1 tick (Low) to 5 ticks (Excellent). See aircon types for how these designs differ.

For the power method, look for the rated power input in the spec sheet or manual. If it is given in kW, multiply by 1,000 (1 kW = 1,000 watts).

Tariff and update schedule

The tariff field starts at 27 cents per kWh. That is the electricity cost NEA's Energy Label assumes for aircons, together with 8 hours of daily use plus 16 hours standby. It is NEA's label assumption, not the current tariff, so replace it with your own rate.

SP Group revises the household electricity tariff every quarter and publishes it on its tariff information page. Enter the figure on your latest bill or on SP Group's page. If you buy electricity on a retailer plan, use the rate your plan charges.

How the calculation works

Label method. NEA works out the label's annual kWh for 8 hours of use a day plus 16 hours standby, as its Energy Label page explains. The calculator divides the annual kWh by 365 days and by 8 hours to get kWh per hour of use, then multiplies by your hours per day and days per month. Because the label's standby share is counted as use, this estimate leans high.

Power method. kWh = watts x hours / 1,000. The rated input is applied to every hour you enter.

For both methods, cost = kWh x tariff, and the yearly figure is the monthly figure x 12.

For example, a label showing 1,000 kWh a year works out to 1,000 / 365 / 8, or about 0.34 kWh per hour of use. At 8 hours a day on 30 days a month, that comes to about 82 kWh a month. Multiply the kWh by your tariff in cents per kWh to get the cost.

Ways to lower the running cost

NEA's energy saving tips for households include these habits, which can bring down your aircon monthly cost:

• Set the temperature at 25 degrees C: "the lower the temperature setting, the more energy used by your air-conditioner."
• Run the aircon for a short while (1 hour) and switch to a fan after that.
• Set the timer to switch off half an hour earlier than usual.
• Close curtains or blinds during the hottest part of the day.
• Check the filter once a month and clean or replace it when necessary. Service the units regularly.

The guide to aircon settings that save electricity goes into more detail. Servicing costs depend on the job, so compare aircon servicing prices when a service is due.

When you buy or replace an aircon, NEA's buying tips say to look at life cycle cost, not just purchase price: life cycle cost = purchase price + annual energy cost x lifespan in years. Appliances with more ticks on the Energy Label are generally more energy efficient, and oversized aircons cost more to run. To weigh up the two split designs, read inverter vs non-inverter aircon and compare the annual kWh on each label.

Limits of this estimate

Compressors cycle, so real use depends on the room, the weather, your settings and the unit's condition. The label method leans high, and the power method applies the rated input to every hour you enter.

Tariffs change, and GST, rebates and retailer plans are not modelled. It is an estimate, not a bill.

Questions