Home energy audit: how to find where your energy goes

An energy audit is a structured check of how a building uses electricity and gas, followed by a list of changes that would reduce that use. For a homeowner or renter, an audit helps identify which appliances, habits and household features are driving the bill?

Your energy bill is not itemised like a mobile phone bill, so it is hard to tell from the bill alone what is using the most power. A home energy audit fills that gap. You can do one yourself in an afternoon, borrow a free measuring kit from a library in some states, or pay an accredited assessor for a formal rating.

Quick facts

• Heating and cooling account for around 40% of average household energy use, followed by appliances at around 25%, hot water at around 20%, and cooking and lighting at around 10%.
• A DIY home energy audit costs nothing, and free audit kits with plug-in energy meters can be borrowed from libraries in South Australia and Western Australia.
• The national Home Energy Rating for existing homes began on 1 July 2026 and replaced the Residential Efficiency Scorecard, which closed in June 2026.
• A Home Energy Rating certificate gives a star rating out of 10 for the building shell and a Home Energy Rating out of 100 for the home's overall energy use.
• NSW homeowners can get $330 off a Home Energy Rating assessment through the NSW Government's subsidised program.
• Business energy audits follow the Australian Standard AS/NZS 3598 and come in three types, from a basic overview to a precision audit of a single system.

What is an energy audit?

An energy audit measures where and how energy is used, identifies waste, and ranks the changes that would save the most money. The term covers a wide range of work, from a homeowner walking through the house with a checklist to an engineer metering a factory's compressed air system for weeks.

For households, there are two main types:

• A DIY home energy audit, where you check your bills, appliances, heating and cooling, hot water, lighting and draughts yourself, using a checklist and, optionally, a borrowed kit.
• A professional home energy assessment, where an accredited assessor visits, collects data on the building and its fixed appliances, and issues a certificate with ratings and upgrade advice. Since July 2026, the nationally recognised version is called a Home Energy Rating.

You may also see the terms "energy efficiency audit" and "home energy assessment". They describe the same process. Businesses use a separate system of audits, which is covered further down this guide.

Where energy goes in a typical home

Knowing the typical split helps you decide where to spend your audit time. The breakdown below is for an average Australian home.

Your own split will differ depending on your climate, the size of your home, whether you use gas, and whether you have solar. A household in Tasmania with electric heating will look very different from a Darwin household running air conditioning most of the year. The point of the audit is to find your numbers, not the average.

How to do a DIY home energy audit

A DIY audit works best in four stages. First, use your bills and meter data to see your usage patterns. Then measure what your home uses when nothing should be running. Next, walk through the house room by room. Finally, put a dollar figure on your biggest energy users. Set aside two to three hours, plus a night for the baseload test.

What you need

• At least 12 months of electricity bills, plus gas bills if you have gas
• Access to your retailer’s app or online account, if you have a smart meter
• A plug-in energy meter
• A fridge thermometer
• A bucket, a measuring jug and your phone’s stopwatch
• A torch and an incense stick
• A notepad or spreadsheet to record what you find

Step 1: Work out your usage patterns

Find the total kilowatt hours (kWh) for each billing period, then divide by the number of days in the period to get your average daily usage. Doing this for every bill across a year shows you when your usage rises and falls, and the pattern usually points to the cause.

If you have a smart meter, your retailer’s app or account will usually show daily and half-hourly usage, which is far more useful than quarterly bills. You can also ask your electricity distributor for your meter data. In the ACT, for example, Evoenergy provides up to two years of consumption and generation data to account holders within 10 business days.

If you have solar, look at your imports from the grid and your exports separately. Your bill only shows what you bought, not everything you used. Our guide to understanding your electricity bill explains where to find each figure.

Step 2: Measure your baseload

Your baseload is the power your home draws when nobody is using anything: fridges, freezers, pool pumps, modems, and devices on standby. It runs 24 hours a day, so even a small baseload adds up across a year.

To measure it:

1. Use your smart meter data for the hours between about 1am and 5am, when the household is asleep. If you don’t have a smart meter, read your meter at bedtime and again when you wake up, and note the hours in between.
2. Leave out any separately metered controlled load for hot water or slab heating, because it is designed to run overnight and will distort the result.
3. Divide the kWh used by the number of hours. Multiply by 1,000 to get your average baseload in watts.
4. Multiply that baseload in watts by 8,760 (the number of hours in a year), then divide by 1,000 to get your annual baseload in kWh.

For example, a home that uses 1.5 kWh between 1am and 6am has a baseload of 300 watts. Over a year, that adds up to 2,628 kWh. At a usage rate of 35c per kWh, that’s about $920 a year spent before anyone switches anything on. Check your own rate in our electricity cost per kWh guide.

If your baseload looks high, use your retailer’s app (if it shows live usage) or a plug-in meter to find which devices are responsible. Standby power alone accounts for about 6% of the average home’s electricity use, according to Your Home, with air conditioners, TVs, home entertainment and computers the biggest contributors.

Step 3: Walk through your home room by room

Take your notepad and check each area of the house. Note anything that is old, running when it doesn’t need to be, or set to a higher temperature than necessary.

Living areas

• Check the type and age of your heating and cooling. A reverse cycle air conditioner is usually far cheaper to run for heating than a gas or electric resistance heater; the Victorian Government describes reverse cycle as much cheaper than gas heating.
• Check the thermostat. Heating set above 21°C or cooling set below 24°C costs more to run.
• Pull out and look at the air conditioner filters. Dusty filters make the system work harder.
• Count the devices left on standby, such as TVs, consoles, soundbars and set-top boxes.

Kitchen

• Put a thermometer in the fridge overnight. It should read between 3°C and 5°C. Your Home notes that each degree colder needs about 5% more energy.
• Test the fridge and freezer door seals by closing the door on a sheet of paper. If the paper slides out easily, the seal is leaking cold air.
• Check the energy rating labels on your fridge, dishwasher and oven, and note the kWh per year figure. The kWh figure is the most reliable way to compare an old appliance with a new one, because star rating scales have changed over time.

Laundry

• Check which wash temperature you normally use. Warm or hot washes use roughly 50% to 85% more energy than cold washes.
• Note how often you use the clothes dryer and its star rating. Your Home estimates a 2-star 7kg dryer used daily consumes about 2,210 kWh a year, compared with about 1,150 kWh for a 6-star model.

Bathrooms

• Measure your shower flow rate. Hold a bucket under the shower on full for 10 seconds, measure the water with a jug, and multiply by 6 to get litres per minute. A flow above 9 litres a minute is worth reducing with a water-efficient shower head.
• Check that exhaust fans vent outside. Exhaust fans are there to remove humidity and keep indoor air healthy. A fan that vents into the roof only moves the moist air elsewhere in the house, where it can condense and cause mould.

Bedrooms and home office

• Look for portable electric heaters, electric blankets left on, and chargers or monitors left plugged in.
• Check whether computers and printers go to sleep when idle.

Garage, outdoors and pool

• Look for a second fridge or freezer. An older fridge could easily cost $200 or more a year to run, and that it shouldn’t sit in a hot garage or veranda.
• Check how many hours a day your pool pump runs. Pool pumps can reach 18% of a home’s energy use.
• Check outdoor lights for timers or motion sensors.

Step 4: Put a dollar figure on your biggest appliances

Plug your energy meter into each appliance you suspect is expensive and leave it for at least 24 hours (a full week is better for fridges and freezers, as they cycle on and off). Record the kWh used, then use this formula:

Annual cost = kWh per day × 365 × your usage rate

For example, an old garage fridge that uses 2 kWh a day costs about $255 a year at 35c per kWh. Recording each result in a simple table makes it easy to see which appliances to deal with first.

You can’t plug a meter into hardwired appliances such as a ducted heater, an oven or a hot water system. For these, switch everything else off and watch your smart meter app while the appliance runs, or multiply the power rating (in kW) on its compliance plate by the hours it runs each day.

If you’re weighing up a replacement, the government’s Energy Rating Calculator compares the running costs of specific models.

Step 5: Check your hot water system

Find your hot water unit and note its type (electric storage, gas, heat pump or solar), its age and its energy rating, if it has one. Check whether it is on a separately metered tariff on your bill, as that changes how much it costs to run.

Don’t turn a storage tank down too far to save energy. In Queensland, hot water must be heated to at least 60°C to prevent the growth of bacteria such as Legionella, and delivered to taps at no more than 50°C to reduce the risk of scalding. The savings come from using less hot water, insulating exposed pipes, and fixing dripping hot taps, not from storing it cooler.

If the unit is more than 10 years old or uses electric resistance heating on your main tariff, note it as a candidate for a heat pump upgrade.

Step 6: Find draughts and gaps in insulation

The most common sources of draughts as:

• doors and windows
• gaps between floorboards, walls, ceilings or cornices
• unsealed vents, skylights and exhaust fans
• gaps around downlights, pipes and cables
• chimneys.

To find them, close the windows and external doors on a windy day, switch on the exhaust fans, and hold a lit incense stick near each likely gap. If the smoke moves sideways or gets drawn in, you’ve found a draught.

If you can safely get into your roof space, use a torch to check whether there is ceiling insulation and whether it has gaps, has been compressed, or has been pushed aside around downlights.

It's important to remember for safety that you don’t draught-proof a room that has an unflued gas heater, as these appliances need fixed ventilation to operate safely. And if you rent, ask your landlord before making changes to the building. Removable door snakes and stick-on seals are usually fine without permission.

Step 7: Turn what you found into an action plan

List each finding with the fix, a rough cost, and who can make the change. Then sort the list into three groups:

1. Free changes you can make today, such as adjusting thermostats, turning off the second fridge, washing in cold water and switching devices off at the wall.
2. Low-cost fixes, such as LED globes, draught seals, a water-efficient shower head, pipe lagging and a timer for the pool pump.
3. Larger upgrades, such as insulation, a heat pump hot water system, reverse cycle air conditioning or solar.

For anything that costs money, work out the payback period by dividing the cost by the yearly saving. A $100 fix that saves $50 a year pays for itself in two years. Do the quick payback items first, and check which rebates and incentives apply in your state before getting quotes for larger upgrades.

Once you’ve made the changes, repeat the baseload test and compare your next bill against the same period last year. This tells you what worked.

Borrow a free home energy audit kit

Several state and local governments lend out audit kits that contain the tools you need to measure your home's energy use.

South Australia: The SA Government's Home Energy Toolkit is available to borrow from all metropolitan libraries and most regional libraries in the state. Each kit contains an appliance meter, an infrared thermometer for checking hot water temperatures and hot and cold spots, a spirit thermometer for rooms and fridges, a compass, a stopwatch for measuring shower flow, and an instruction guide. The kits are not sold to individuals.

Western Australia: According to energy.gov.au, 74 WA local governments have partnered with Switch Your Thinking to lend DIY home energy audit kits through more than 100 libraries and community resource centres. The kit includes a thermal imaging camera for finding draughts and insulation gaps, a plug-in energy monitor, a basin flow measuring cup, and an instruction manual. Loan periods vary by library. The City of Perth, for example, lends its kit for a maximum of 7 days.

Other states and territories: Many councils and libraries across NSW, VIC and QLD lend energy meters or audit kits through their own programs. Search your local library's catalogue for "energy audit kit" or "energy meter", or ask your council's sustainability team.

Professional home energy assessments: the Home Energy Rating

A professional assessment goes further than a DIY audit because an accredited assessor models the whole house, including its construction, using software. Since 1 July 2026, the national program for existing homes has been the Home Energy Rating, delivered under the Nationwide House Energy Rating Scheme (NatHERS). The NSW Government recommends using an assessor accredited under NatHERS, and describes it as the only scheme recognised in NSW for in-home energy assessments.

What the assessor checks

A Home Energy Rating assessment takes into account:

• the home's design, construction materials, insulation, window types and shading
• the efficiency of fixed appliances, such as air conditioners, heaters, hot water systems, pool and spa pumps, and lighting
• any solar panels or battery on site
• the local climate.

An on-site visit can take up to 2 hours depending on the size of the home. The assessor then calculates the home's energy use using accredited NatHERS software and sends you the certificate.

Unlike a DIY audit, a Home Energy Rating focuses on the building and its fixed appliances. Plug-in appliances and your household's habits are not the focus, so a DIY audit is still useful alongside it.

What the certificate tells you

The Home Energy Rating certificate has two main ratings, as explained by the NSW Government:

In both cases, a higher number means lower energy bills. The certificate also includes upgrade guidance for your climate zone. For context, the NatHERS guide to the trial certificate states that the average Australian home has an estimated star rating of less than 3 out of 10, while new homes built under the National Construction Code must reach a minimum of 7 stars.

An existing-home rating is for household decisions only. NatHERS notes it cannot be used to show compliance with the National Construction Code for a new home or major renovation.

What a Home Energy Rating costs

There is no set national price. According to the Queensland Department of Housing and Public Works, the assessor sets the fee based on the home's size, location and design complexity. The NSW Government suggests asking each assessor for the total cost, any extra fees such as travel or revised certificates after upgrades, and what else is included, such as thermal imaging or a recommendations report. Compare quotes from more than one assessor.

Help with the cost is available in NSW:

• Subsidised Home Energy Ratings program: NSW homeowners can get $330 off the total cost of a Home Energy Rating assessment. The program matches you with an accredited assessor, and you pay a flat fee minus the subsidy.
• Home Energy Saver loans: NSW homeowners and landlords with a combined taxable household income of up to $210,000 can get a zero-interest loan of up to $15,000 for a Home Energy Rating assessment and energy saving upgrades.

You can find an accredited assessor in any state on the Home Energy Rating assessor register.

What happened to the Residential Efficiency Scorecard?

The Residential Efficiency Scorecard was the main rating program for existing homes from 2017. The program closed in June 2026, with NatHERS replacing it for existing homes. If you have an older Scorecard certificate, it still describes your home as it was at the time of assessment, but new assessments are now done under the Home Energy Rating.

DIY audit or professional assessment?

Many households get the most value from doing both: a DIY audit first to catch the easy wins, then a professional assessment before spending money on insulation, windows, hot water or heating upgrades. Renters can use either to understand their home's performance. The NSW Government notes that renters can use an assessment to support a request for upgraded fixed appliances, such as a hot water system or air conditioner.

Home energy audits vs business energy audits

Business energy audits work differently from home audits. They follow a formal Australian Standard, are usually done by an energy auditor or engineer rather than a home energy assessor, and focus on equipment and processes as well as the building.

According to energy.gov.au, business audits should be completed to the relevant Australian Standard: AS/NZS 3598.1:2014 for commercial buildings, AS/NZS 3598.2:2014 for industrial activities, or AS/NZS 3598.3:2014 for transport. The standard sets out three types of audit:

The key differences from a home audit are:

• Data requirements. Energy.gov.au recommends providing an auditor with at least 12 months of energy bills for a Type 1 audit, plus sub-metering data, control system information and maintenance records for a Type 2 audit.
• Auditor accreditation. Training and accreditation for business energy auditors varies between states and territories, and the Energy Efficiency Council lists service providers. Home assessments use the national Home Energy Rating accreditation instead.
• Scale. Energy-intensive businesses using more than 0.05 petajoules a year are treated as large energy users and follow separate guidance on energy efficiency assessments.

A small business in a shop or office can still use the DIY home audit steps above as a starting point, particularly for lighting, heating and cooling, and equipment left on overnight. Energy.gov.au suggests asking a prospective auditor which type of audit your business needs and why, and whether they can help implement the savings they identify.

After the audit: check your plan as well

An energy audit cuts the amount of energy you use. The price you pay for each unit is a separate lever. Once you know your usage pattern, compare it against your current plan:

• If most of your usage falls in the evening, a flat-rate plan may suit you better than a time-of-use plan.
• If your audit shows you can shift dishwashers, washing machines or pool pumps to the middle of the day, a time-of-use plan or solar soak tariff may lower your bill further.
• If you own solar, compare your feed-in tariff with what other retailers offer.

Our electricity cost per kWh guide shows the reference prices for your area, and you can compare electricity plans with UtilityClub to see whether a different plan would suit your new usage pattern.

Photo by Jakub Żerdzicki on Unsplash