What Energy Rating Should New Homes Have in Australia?

Overview

Energy efficiency in new homes is increasingly regulated, and the star rating system used across Australia — NatHERS — is one of the most important but least understood aspects of a new build for most buyers.

Understanding what the rating means, what the legal minimum is, and what features contribute to a higher rating gives you the knowledge to ask the right questions when comparing builder inclusions.

NatHERS Explained

NatHERS stands for Nationwide House Energy Rating Scheme. It's a star-based rating system (0–10 stars) that measures a home's thermal performance — how much energy is needed to heat and cool the home to a comfortable temperature based on the climate zone.

The rating is calculated by accredited NatHERS software (AccuRate, BERS Pro, or FirstRate5) based on the home's design — including insulation values, window sizes and types, orientation, shading, and construction materials. It's an estimate of thermal performance, not a measure of actual energy use.

If your project uses a NatHERS software pathway, a NatHERS certificate records the assessed design and star rating. Other permitted compliance pathways may use different documentation, so ask your certifier or builder what energy-efficiency evidence applies to your project.

Star Ratings Breakdown

What Affects Your NatHERS Rating?

• Insulation R-values (ceiling and walls)High impact. Ceiling insulation is the most cost-effective thermal investment. Higher R-value = better performance.
• Window glazing type (single vs double)High impact. Double-glazed windows dramatically reduce heat transfer. Most standard builds use single-glazed — a meaningful upgrade.
• Window size and orientationHigh impact. North-facing windows (in the southern hemisphere) allow passive solar heating in winter. East/west-facing large windows increase heat gain.
• Shading devices (eaves, awnings)Moderate impact. Adequate eaves block high summer sun while allowing lower winter sun — a passive design feature.
• Building fabric air tightnessModerate impact. Draught sealing and airtightness reduce thermal loss. More significant in cooler climates.
• Slab type and thermal massLower impact. Concrete slabs provide thermal mass that stabilises internal temperatures but is a minor factor compared to insulation and glazing.

What Builders Claim vs Reality

Many builders advertise "6-star energy rating" or "7-star NatHERS" as a selling point. NCC 2022 uses 7 stars as the national thermal-performance benchmark, but whether that exact rating is the legal minimum for a particular home depends on the jurisdiction and compliance pathway.

What varies between builders isn't just the final star rating — it's the specification used to achieve compliance. Two homes with the same rating can use different combinations of insulation, glazing, orientation and shading, which can also affect noise, daylight, condensation risk, resilience and the cost of future upgrades.

Included or Upgrade?

Frequently Asked Questions