Document - NatHERS Certificate
What is a NatHERS Certificate and How Does It Affect My Design?
If you are designing a new home, you will eventually hear your architect or certifier talk about "Star Ratings" or "Thermal Performance." This is where NatHERS comes in.
While BASIX looks at the overall sustainability of your home (water and energy), NatHERS specifically focuses on how comfortable your home is to live in without relying heavily on air conditioning or heating.
Here is a simple guide to understanding NatHERS and why a high star rating is more than just a box to tick for council approval.
What is NatHERS?
NatHERS stands for the Nationwide House Energy Rating Scheme. It is a star-rating system (ranging from 0 to 10 stars) that measures the thermal performance of a home.
In simple terms, it rates how well your house design can keep you warm in winter and cool in summer naturally. The higher the star rating, the less energy you will need to heat or cool the space.
Why do you need it for a DA/CC or CDC?
In New South Wales, NatHERS is the standard assessment method used to satisfy the "Thermal Comfort" section of your BASIX certificate.
To get your Development Application (DA) or Complying Development Certificate (CDC) approved, your design generally needs to achieve a minimum 7-star rating (under current National Construction Code standards). Without this rating, your project cannot pass BASIX, and therefore cannot be approved for construction.
What information is included in a NatHERS Certificate?
A NatHERS certificate provides a detailed breakdown of the building's predicted energy use. It includes:
The Star Rating: A score out of 10.
Heating and Cooling Loads: Estimates of how much energy (in megajoules) is required to keep each room comfortable annually.
Building Specifications: The specific materials required to achieve that rating, such as insulation types, window glazing specs (U-values and SHGC), and floor coverings.
Shading: Details on eaves, pergolas, or shade structures required to block the summer sun.
When is it required?
Like BASIX, a NatHERS assessment is required during the design phase, before you lodge your application.
Your architect will usually send the preliminary plans to an energy assessor. The assessor will run the design through simulation software to calculate the rating. If the design scores low (e.g., 5 stars), the design must be tweaked—usually by adding insulation or changing windows—before the final certificate is issued.
Common Pitfalls & Architect’s Tips
A common misconception is that you can "fix" a poor design just by adding more insulation later. This is often expensive and ineffective.
Architect’s Tip: The cheapest way to get a high Star Rating is good orientation, not expensive glass. If we design your home to capture northern sunlight in winter and block it in summer, you can often achieve 7 stars with standard windows and insulation. If a house faces west with no shading, you might spend thousands on high-performance "Low-E" glass just to scrape across the compliance line.
How to obtain a NatHERS Certificate
A NatHERS certificate must be prepared by an accredited assessor using specialized software (such as BERS Pro, FirstRate5, or Hero).
In our studio, we integrate this step into our design workflow. We collaborate with the assessor early in the process to ensure we are designing for thermal performance from day one, rather than trying to force a bad design to comply at the last minute.
BASIX vs. NatHERS: What is the Difference and How Do They Work Together?
While they both deal with sustainability and energy efficiency, they serve different purposes. Understanding the distinction helps you see where your money is going during the design stage.
The Short Answer
Think of BASIX as the "Umbrella Policy" for New South Wales. It covers everything: water, energy, and thermal comfort.
Think of NatHERS as a "Measuring Tool." It is a specific calculation method used to prove you meet the thermal comfort part of the BASIX requirements.
What is the main difference?
The biggest difference is scope.
BASIX (Building Sustainability Index) is broad.1 It looks at the whole picture of your home's sustainability. It measures water consumption (tanks, taps), energy use (hot water, air conditioning), and thermal performance.2 BASIX is exclusive to NSW.
NatHERS (Nationwide House Energy Rating Scheme) is specific.4 It focuses only on the thermal performance—how well the physical structure (walls, roof, windows) keeps the heat in or out. NatHERS is a national standard used across Australia.
How do they work together?
In NSW, they work hand-in-hand.
To get your BASIX Certificate, you must pass three sections:
Water Target: (e.g., rainwater tanks, efficient showerheads).
Energy Target: (e.g., efficient appliances, lighting).
Thermal Comfort Target: This is where NatHERS steps in.
Most architects and certifiers use a NatHERS assessment to generate the data needed to pass the "Thermal Comfort" section of BASIX.6 Your energy assessor will run a NatHERS simulation to get a Star Rating (e.g., 7 Stars).7 They then enter this rating into the BASIX system to tick that box.
Summary
NatHERS tells you how well your house fights the weather.
BASIX tells the government your house is sustainable enough to be built in NSW.
Ready to build a comfortable, efficient home?
Achieving a 7-star energy rating requires smart design and careful planning. If you need help designing a home that is both beautiful and compliant with NSW energy standards, contact OAK Architecture and Design today.
