A NatHERS Assessment is a building energy rating for houses and apartments under the Nationwide House Energy Rating Scheme. It predicts the thermal performance of a dwelling based on design features such as orientation, glazing, shading, insulation, construction type and climate zone. The output is a star rating from 0 to 10 stars – the higher the stars, the better the predicted comfort and the lower the expected energy needed for heating and cooling. NatHERS assessments must be completed by accredited assessors.

NatHERS ratings are undertaken by accredited assessors using approved software tools. In NSW, NatHERS is commonly used to demonstrate thermal comfort for BASIX Certificates. Evergreen Energy Consultants provides both services so you can streamline approvals.

What does the assessment involve?

An assessor builds a digital model of your home from the architectural plans and inputs details such as window sizes and types, wall/roof construction, insulation R‑values, ceiling heights and shading devices. The software simulates how the home performs across a typical year in your local climate (e.g., Sydney, Newcastle, Wollongong, Central Coast or Byron Bay), estimating how much heating and cooling energy would be required to maintain comfort.

What affects your star rating?

• Orientation and layout: Placing living areas to capture winter sun and using shading for summer heat can significantly improve ratings.
• Glazing: Window area, frame material and glass type (e.g., double‑glazing, low‑E) have a big impact.
• Insulation: Adequate wall, roof and subfloor insulation reduces heat transfer.
• Thermal mass: Materials like concrete slab can stabilise internal temperatures when used correctly.
• Air leakage: Tighter building envelopes help maintain set temperatures with less energy.

Why NatHERS matters for NSW projects:

A compliant NatHERS rating helps you satisfy BASIX thermal comfort targets and provides practical guidance for design decisions that improve comfort and reduce running costs. It’s not just about approvals, it’s about living in a home that feels better year‑round in your region, whether that’s coastal humidity on the Central Coast or cooler winters in the Hunter Valley.

Minimum stars and better‑than‑minimum outcomes:

Regulations set minimum star requirements (which may vary by building class and compliance pathway). Many clients aim for a higher star outcome to future‑proof comfort and energy bills. Evergreen EC can model design options to help you choose cost‑effective upgrades (e.g., selectively upgrading glazing or adjusting shading rather than over‑specifying everywhere).

Deliverables you receive:

You’ll receive a NatHERS certificate/report showing the star rating, heating and cooling loads, and a summary of design features that underpin the result. Where performance is borderline, we’ll include practical recommendations to lift the rating without compromising design intent or budget.

Typical timeline and process:

1. Send your plans: floor plans, elevations, sections and site plan.
2. We model: our accredited assessors build and optimise the digital model.
3. Review: we discuss any simple changes that could lift performance.
4. Finalise: we issue the NatHERS certificate to support your BASIX submission.

Most projects are turned around in about three business days once we have complete information.

Local expertise across NSW

From Sydney infill sites to Newcastle and Lake Macquarie coastal homes and apartments in Byron Bay or Wollongong, local climate assumptions matter. Evergreen EC’s experience across NSW means your rating reflects realistic performance in your area, and your project gets advice that works on the ground.

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Written by Evergreen Energy Consultants — accredited BASIX and NatHERS assessors providing residential energy assessments across NSW.