Making sense of your smart meter data

Victorian homes have smart meters, and the meter belongs to the electricity distributor for your area. You don't choose your distributor; it depends on where you live. In Melbourne's west, Powercor supplies Laverton, Altona Meadows, Point Cook, Werribee, Hoppers Crossing and Tarneit among others, Jemena's area reaches Williamstown and Footscray, and CitiPower supplies parts of Port Melbourne.

You can ask your retailer or distributor for your smart meter data, and some have online portals or apps where you can view it or download a file. You will need the National Metering Identifier (NMI) from your bill. The Victorian Government's Victorian Energy Compare site can also use your smart meter data, through your NMI, to compare offers against how you actually use power.

Get at least a year if you can. Melbourne's seasons change the picture a lot, and one month on its own tells you very little.

Most portals show each day as a chart of usage in half-hour or similar blocks. Pick an ordinary weekday in each season and look at its shape before worrying about the totals.

Three things matter. The baseline is the lowest, flattest part of the night, when the house is asleep. The peaks are when big loads run. The seasonal shift is how winter and summer days differ from mild spring and autumn days, which shows roughly how much goes on heating and cooling.

If you have solar, the chart may show only what you drew from the grid, with a dip through the middle of the day. Some portals show export separately. That is normal; just read the evening and overnight hours with it in mind.

Big appliances leave recognisable shapes, which makes it possible to tell them apart without any extra metering.

Compare a cold July weekday with a mild October one: the difference is roughly what heating costs you on a cold day. Do the same with a hot February afternoon against a mild one for cooling. At Laverton, July averages a minimum of 5.2 °C and there are about 27 days a year at or above 30 °C, so both seasons show up clearly.

A baseline that jumps and stays up, without a new appliance, suggests something has been left on or has started running constantly. A heated towel rail, a spa heater or a fridge with a failed door seal can all do it.

Heating or cooling that runs longer each day for the same comfort can point to a dirty filter, a refrigerant leak or a failing part. Dirty filters significantly cut airflow and efficiency, and in federal bench tests common faults in air conditioning equipment caused average energy losses of 14% to 20% in most tests.

A hot water block that grows longer, or moves onto general power when it used to sit on the controlled load, can mean a failing element, a thermostat fault or switching that has changed. A load running through the night when the heating should be off may be a timer that lost its settings after a power cut.

Once you know when things run, you can line them up with your tariff and your solar. Moving a heat pump water heater's timer into the hours your panels produce, scheduling EV charging into a cheaper window, or starting the heating half an hour before you get up instead of at 5am are all changes the data can justify.

Check the set temperatures behind those heating and cooling blocks. The Victorian Government suggests 18 to 20 °C for heating and 24 to 26 °C for cooling living areas, and says every degree beyond that adds around 10% to running costs.

After any change, compare like with like: similar weather, a matching weekday, a couple of weeks later. One day's numbers can easily mislead.

If the chart shows something you can't explain, start with the simple checks. Walk around at night and see what is on, check the timers on the heating, hot water and pool, and look for anything you'd forgotten was plugged in.

If a pattern points to a fault, such as a hot water element tripping or a heating system that never switches off, an electrician or air conditioning technician can test it. Screenshots of the charts make that conversation much quicker and help us go straight to the likely circuit or appliance.

Questions about the meter itself, the tariff or the bill go to your retailer first.