How to prepare for a NatHERS existing home assessment, and what the LiDAR scan does

So you’ve booked a NatHERS assessment for your home, or you’re about to. Good news: there’s nothing to study and nothing to fix beforehand. But a little preparation makes the visit quicker, and it helps your assessor get an accurate result.

Here’s what to dig out, how to get the house ready, what happens on the day, and what that LiDAR scan is actually doing as your assessor walks from room to room.

Haven’t booked yet? Joining MyCool Home is free, and so are your savings insights. Get a free ComfortScore first →

What a NatHERS existing home assessment is

NatHERS, the Nationwide House Energy Rating Scheme, has been rating new homes for more than 30 years. New homes are rated from their plans before they’re built. An existing home is different: an accredited assessor comes to your place, records what’s actually there, and puts it into NatHERS-accredited software.

You end up with a Home Energy Rating certificate showing two numbers: a Home Energy Rating from 0 to 100+ for the whole home, and a Star Rating out of 10 for the building itself. If you want the background first, start with what a home energy rating is, and whether you need one.

Before the day: what to gather

The official guidance asks you to share any background information you have. None of it is compulsory, but each item saves your assessor guessing:

• Building plans or drawings, if you have them, even old council copies
• Renovation history: what was done and roughly when, such as an extension, new windows or a ceiling insulation top-up
• Appliance receipts or manuals for things like air conditioners, heaters and the hot water system
• Any previous assessments of the home

Tip: lost the receipts? A clear photo of the model label on each appliance usually helps just as much.

Get the house ready

Your assessor will go through every part of the home, including an attached garage and any shading structures like a pergola. Before they arrive:

• Put personal items away
• Make sure every room is easy to get into and free of clutter
• Secure your pets
• Open the curtains and blinds so the windows are easy to see

A couple of extra tips that make life easier: clear the space in front of windows and doorways, and if you have a ceiling access hatch, make sure it can be reached.

Your assessor will also give you a Client Information and Consent Form, which explains what to expect and asks for your consent before they start.

On the day

Book a time when you can be home. A typical visit takes 2 to 3 hours, depending on the size and complexity of your home.

Your assessor records the things that drive the rating: how the home is built, insulation, windows, shading, gaps where air leaks in (around windows and doors, for example), your appliances, rooftop solar and more. Expect them to look closely, take measurements and photos, and maybe ask you a few questions about what’s changed over the years.

What the LiDAR scan does (and doesn’t)

Some assessors now scan the home instead of measuring every wall by hand. LiDAR is a sensor built into recent Pro models of iPhone and iPad. It measures distance with light, so as your assessor walks from room to room it captures the shape of each room, the walls, and the windows and doors, building a 3D model that becomes your floor plan.

That means less tape-measuring and fewer manual errors, which can make the visit quicker for you.

What a scan can’t do is see inside things. It doesn’t know what insulation is in your walls or ceiling, what type of glass is in your windows, or how efficient your hot water system is. Your assessor still checks, records and photographs all of that, which is why the house prep above still matters.

MyCool Home Accredited, the software we build for assessors, uses this kind of LiDAR scanning on iPhone and iPad, then lets the assessor add everything the scan can’t know. See how it works for assessors.

After the visit: your certificate

Your assessor puts everything into NatHERS-accredited software and sends you a Home Energy Rating for existing homes certificate. It includes:

• Your Home Energy Rating (0 to 100+): how much energy the whole home uses, including fixed appliances, solar and batteries. 100 means net zero, and homes that export more than they use can score up to 150.
• Your Star Rating (0 to 10): how well the design and construction keep the home at a comfortable temperature. For comparison, 7 stars is the minimum for new houses under the National Construction Code 2022.
• Estimated annual energy use
• Upgrade guidance to help you plan what to do next

One thing to know: this certificate can’t be used for National Construction Code compliance if you’re planning a major renovation. That needs a new homes certificate. For a walk through every section, see the Home Energy Rating certificate, explained.

Frequently asked questions

How long does a NatHERS existing home assessment take?

Usually 2 to 3 hours on site, depending on the size and complexity of your home. Source: homeenergyrating.gov.au.

Do I need to be home for the assessment?

Yes. The official guidance is to book a time when you can be home to meet your assessor, and every area of the home needs to be accessible.

What should I have ready?

Building plans if you have them, your renovation history, appliance receipts or manuals, and any previous assessments. On the day, put personal items away, clear clutter, secure pets and open the window coverings.

What is a LiDAR scan in a home energy assessment?

It’s a 3D scan of your home taken with the LiDAR sensor on a recent Pro iPhone or iPad. It captures room shapes, walls, windows and doors, so your assessor spends less time measuring by hand. It can’t see hidden things like insulation, so they still check those in person.

Can I use the certificate to get a renovation approved?

No. A Home Energy Rating for existing homes certificate can’t be used for National Construction Code compliance. Major renovations may need a NatHERS new homes certificate instead. Source: homeenergyrating.gov.au.

Find an assessor, or start for free

Ready to book? The government’s Find an Assessor tool lists accredited assessors near you.

Not sure it’s worth it yet? Joining MyCool Home is free, and so are the insights. Get your ComfortScore, then use our calculator to see what each upgrade could save in your home before you spend anything.

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Sources: homeenergyrating.gov.au, How to get an assessment and Measuring the energy efficiency of existing homes (both updated 24 June 2026). Last verified 18 October 2026.