Choosing a NatHERS Assessor: What to Look For
How to select the right NatHERS assessor for your project, including accreditation, software tools, costs, and questions to ask before you engage.
Why Your Choice of Assessor Matters
A NatHERS assessor does more than just produce a compliance certificate. A good assessor works with you and your designer to optimise the building's thermal performance, potentially saving thousands of dollars in construction costs and delivering a more comfortable home. Conversely, a poor assessor may simply provide a pass-or-fail result without helping you understand how to improve your design.
Choosing the right assessor is one of the most important decisions you will make early in your building project. Here is what to look for.
Check Accreditation
All NatHERS assessors must be accredited by one of the three Accrediting Authority Organisations (AAOs):
- ABSA (Australian Building Sustainability Association)
- Design Matters National (DMN)
- HERA (House Energy Rating Association)
Accreditation ensures the assessor has completed the required training, demonstrated competency in using NatHERS-accredited software, and maintains ongoing professional development. You can verify an assessor's accreditation by checking with the relevant AAO or by using our assessor directory.
Be wary of anyone offering NatHERS assessments who cannot provide proof of current accreditation. Unaccredited assessments are not accepted by building surveyors or councils.
Software Tools
NatHERS assessors use one of four accredited software tools to model homes and calculate star ratings:
- FirstRate5 — the most widely used tool in Victoria and several other states, developed by the Victorian Government
- AccuRate — developed by CSIRO, used across Australia
- BERS Pro — developed by the Queensland Government, popular in Queensland and northern Australia
- Hero — a newer cloud-based tool gaining adoption across multiple states
All four tools use the same NatHERS calculation engine (the Chenath engine), so they should produce comparable results for the same design. However, assessors are typically most proficient with one or two tools, and some tools may be better suited to certain building types or climate zones.
The choice of software is generally less important than the assessor's skill and experience. Ask which tool they use and why, but do not choose an assessor solely based on their software.
Questions to Ask Before Engaging an Assessor
Before you commit, ask potential assessors the following questions:
- Are you currently accredited? Request their accreditation number and the AAO they are registered with.
- How many assessments have you completed? Experience matters. An assessor with hundreds of completed assessments will be faster and more accurate than someone just starting out.
- What software do you use? Understand which tool they are proficient in.
- Do you provide improvement recommendations? The best assessors will suggest specific design changes to improve your star rating, not just tell you the current result.
- What is your turnaround time? Most assessments take 3-7 business days once plans are provided, but busy periods can extend this.
- What information do you need from me? A good assessor will provide a clear checklist of required documents (typically architectural plans, specifications, and site details).
- Do you assist with NCC 2022 Whole of Home compliance? Not all assessors currently offer WoH assessment, so check if you need this service.
Cost Expectations
NatHERS assessment fees vary depending on the complexity of the project, the assessor's location, and their experience level. As a general guide:
- Standard single-storey home — $300 to $600
- Double-storey home — $500 to $800
- Complex or large homes — $700 to $1,200+
- Multi-unit developments — priced per unit, often with volume discounts
Be cautious of assessors quoting significantly below these ranges. Very low fees may indicate a rushed assessment with limited design advice. Equally, the most expensive assessor is not necessarily the best — look for a balance of fair pricing, demonstrated experience, and willingness to collaborate.
Most assessors include one round of revisions in their fee. If your design changes significantly after the initial assessment, expect to pay for a re-assessment.
What to Look For in a Good Assessor
Beyond the basics of accreditation and pricing, the hallmarks of an excellent NatHERS assessor include:
- Proactive communication — they explain results clearly and respond promptly to questions
- Design collaboration — they work alongside your architect or designer to optimise the rating, not just score it
- Transparent reporting — they provide a detailed report showing how each element contributes to the overall rating
- Local knowledge — familiarity with your climate zone and local construction practices
- Professional indemnity insurance — reputable assessors carry PI insurance to protect both themselves and their clients
Finding the right assessor early in your project can make a significant difference to the outcome. Use our assessor directory to search for accredited professionals in your area.