The Extra Cost of Energy

How much extra are Aussies paying on their energy bills to support live-at-home adult kids or extra housemates?

With high rent, unaffordable housing, and the rising cost of living, a recent report revealed that 72% of 19-year-olds are still living with their parents.  More adults are choosing to stay at home longer or opt for co-living arrangements with friends or housemates. While living with others can help younger adults save on rent, it can also increase energy bills for parents or live-in landlords. 

The energy comparison service, iSelect, combined appliance energy use data, usage habits of Australians aged 18 to 29, and state electricity prices to uncover the cost of energy when living with an additional adult. The study examined low, medium, and high usage profiles to capture different behaviours and the associated costs, ranging from light users who rarely switch things on, to heavy users who rely on multiple devices, take long showers and use appliances more frequently.  

Estimated annual energy costs by usage level

Even a low-usage young adult uses around 1,800 kWh per year, costing households approximately an extra $436 annually. At moderate usage, this rises to almost 3,000 kWh per year, which equates to around $698 in extra energy costs. A high-usage young adult can add 4,648 kWh per year, costing parents or live-in landlords around $1,061 annually. The increase is steep, with costs over doubling from low to high usage, showing how lifestyle habits like streaming, gaming, and long showers can quickly drive-up bills. 


The data shows how frequently 18–29-year-olds living at home use different devices and appliances, as well as the energy costs involved. The essentials, such as showers, lights, and kettles, are universally used, forming the baseline energy demand for every household with an adult child. Alone, these essentials can cost parents or live-in landlords roughly $559.42 annually at high usage.  

Electronics, while widely used, have a low additional cost; on average laptops, headphones, and smartphones, cost less than $7 per year each. While gaming devices, used by roughly half of young adults living at home (stationary consoles 48%, gaming PCs 52%), are very energy-intensive; they can cost bill payers up to $85 per year at high usage, depending on the console.  

Household appliances are widely adopted, with washing machines (83%), microwaves (77%), and vacuum cleaners (75%) representing significant contributors to household energy costs. Discretionary items like clothes dryers (49%), and air fryers (55%) aren’t found in every home. However, when used, their high energy use can cost an average of $18.56 for use of a dryer and $56.51 for an air fryer annually per device.


South Australia stands out with the highest average electricity rate at $0.44 per kWh. Parents or live-in landlords in the state face the most significant annual hit of approximately $1,463 for a high-usage adult and an average of $1,008 across usage levels. In contrast, Victoria is the cheapest state, with rates of just $0.26 per kWh. Households there pay around $586 on average for an extra adult, which is about $423 less than those in South Australia.  

Across the eastern seaboard, costs sit around the national average. New South Wales ($747), Queensland ($754), and the ACT ($679) all show consistent pricing for parents with young adults at home. Western Australia and the Northern Territory sit slightly below this, averaging $739 and $689 respectively, while Tasmania households pay the second lowest at around $650 per year on average.  

Julia Paszka - General Manager – Utilities & Credit Cards

“With many young adults living at home longer due to rising living costs or moving in with friends in house shares, it’s important for households to understand the full impact on their energy bills. Everyday habits, such as taking a long shower or using a tumble dryer, can add up to hundreds of dollars a year.  

“By being aware of these costs, parents and housemates can make small changes that add up, helping everyone save on energy without compromising their lifestyle. At iSelect, we help Australians compare energy plans from a range of providers to help find one that is best suited to their lifestyle and budget.” 

Julia Paszka

General Manager – Utilities at iSelect

iSelect General Pty Ltd (ABN 90 131 798 126. AFSL 334115) has partnered with Compare the Market (ABN 83 117 323 378. AFSL 422926) to compare a range of car insurers and policies. Not all providers in the market or all policies offered by the partners are compared and not all policies or special offers are available to all customers.

A number of our participating general insurance brands are arranged by Auto & General Services Pty Ltd ACN 003 617 909 on behalf of Auto & General Insurance Company Limited 111 586 353, both of which are related entities of iSelect Limited. Our relationship with those companies does not impact the integrity of our comparison service. Click here to view iSelect’s range of providers.

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