Question 1

What is the difference between a home energy audit and an assessment?

Accepted Answer

A home energy audit is a behavioural/diagnostic walk-through that identifies quick wins in an existing home — typically $300–$600 and produces a prioritised upgrade list. A NatHERS home energy assessment is a formal software-modelled star rating (0–10) required for new builds and major renovations under NCC 2022 — $300–$700 and produces a certificate accepted by council. Audits look at how you use the home now; assessments rate the building's thermal performance regardless of behaviour.

Question 2

Which one do I need for a new build or extension?

Accepted Answer

A NatHERS assessment — it's mandatory. NCC 2022 requires 7 stars plus a whole-of-home energy budget on all new dwellings and most additions. An audit has no regulatory standing. NSW builds also need a BASIX certificate on top of NatHERS.

Question 3

Which one do I need to reduce my energy bills?

Accepted Answer

Start with a home energy audit. Audits are behaviour and appliance focused and typically identify $500–$1,500 in annual savings from free/low-cost changes (thermostat, standby, LED, draught tape). If you're planning a renovation over $15k, upgrade to a full NatHERS assessment so the upgrades are modelled against a star rating that unlocks state rebates.

Question 4

Are Victorian Residential Efficiency Scorecard reports audits or assessments?

Accepted Answer

The Victorian Residential Efficiency Scorecard is a government-backed existing-home rating (0–10 stars) — closer to an assessment than an audit. It rates the building shell and fixed appliances but not occupant behaviour. Sits between a $500 audit and a full NatHERS assessment; often bundled with VEU rebate applications.

Question 5

Can one assessor do both?

Accepted Answer

Yes — most NatHERS-accredited assessors also offer walk-through audits (or a combined 'renovation plan' service) for $500–$900. If you're unsure which you need, ask for a combined pre-renovation consult. The assessor can then upgrade the report to a formal NatHERS certificate if you proceed to building works.

Your situation	What you need
Building a new home	NatHERS assessment (mandatory)
Adding an extension or granny flat	NatHERS assessment (mandatory)
Renovating over $50k (NSW)	BASIX + NatHERS
Staged retrofit for star gains	NatHERS assessment (unlocks rebates)
High bills, no renovation planned	Home energy audit
Selling in ACT	EER rating (assessor-issued)
Existing home, VIC, want a rating	Victorian Scorecard (assessor-issued)

Home Energy Audit vs Assessment — Which One Do I Actually Need?

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