What are watts and kilowatts?
To understand your bill it helps to understand the way power is measured.
Electricity is usually measured in watts—one watt is equivalent to one joule of energy per second. A kilowatt (kW) equals 1,000 watts. A megawatt (MW) equals 1,000 kilowatts.
The amount of electricity used over a certain time period is typically given in kilowatt hours (kWh). In one hour, a 500 watt appliance will consume 500 watts or 0.5 kWh of energy.
The features on electricity bills vary depending on who your retailer is—but all bills have key details in common.
Average daily usage. This is measured in kilowatt hours (kWh). To get an idea of how much electricity your household uses your bill should have information on your daily and total usage for the billing period, and how this compares to previous periods.
To get a general idea of how your household energy usage compares to households of a similar size in your area you can use the tool on EnergyMadeEasy.gov.au.
Greenhouse Gas Emissions
The greenhouse gas emissions from the energy used—usually measured in tonnes and illustrated on some bills by a line or bar graph. The average Australian household emits around 14 tonnes of greenhouse gases a year, including personal transport and the decay of waste in landfill.
Charges for this bill. The breakdown of the charges in your bill. This includes the type of tariff (e.g. peak or off-peak), different meter charges, variable and fixed charges, rebates and GST.
Fixed charges (supply charges). These are daily charges that do not change regardless of how much energy is used by that particular household. Although each retailer can structure their charges differently, many retailers link their fixed charges to the costs involved in supplying power to your home.
Variable charges (consumption charges). Relates to usage—the amount of energy consumed by that particular household charged per kWh.
Time-of-use tariffs. Retailers can offer different pricing arrangement for electricity depending on the time of day—this is usually divided into peak and off-peak. An interval or smart meter is required to access this type of tariff.
Power Hungry Air Conditioners
Air conditioners, even the most efficient, newest models, are the most energy hungry appliances in the home. In a typical Aussie household on a normal summer day, no other single appliance consumes as much electricity as the air conditioner. During summer, one-quarter of the power bill goes to keeping cool. An average family residence will consume just over 2,800 kilowatt-hours of electricity per year to run air conditioners.
At the average national electricity cost of 12 cents per kilowatt-hour, a typical window air conditioner running 12 hours per day uses 335 kilowatt-hours per month and costs around $40 monthly to operate. Common ducted reverse cycle air conditioning uses 1,300 kilowatt-hours per month and costs just over $150. A regular ceiling fan set on high for 12 hours per day costs about $3.50 per month.
Fans and air conditioners are not necessarily mutually exclusive in today’s home, using a ceiling fan in conjunction with an air conditioner can be a good way to conserve energy and remain comfortable in the home. A room that “feels” cooler to occupants allows you to nudge the air conditioning thermostat slightly higher, saving more electricity than the energy-stingy fan consumes and reducing net utility costs.