BASIX and Home Energy Ratings both relate to residential energy performance, but they are used for different purposes. BASIX is the NSW sustainability assessment pathway for residential development approvals. A Home Energy Rating is used to assess the energy performance of an existing home and can help owners, buyers, renters and upgrade programs understand how the home performs and what improvements may be possible.
The simplest difference is this: BASIX usually belongs to the approval process for new residential development, major renovations or qualifying pool and spa projects in NSW. A Home Energy Rating belongs to the emerging national pathway for understanding existing homes, including their thermal performance, energy use and upgrade opportunities.
BASIX is used for NSW residential development approval and covers water, energy use and thermal performance. A Home Energy Rating is used to rate the performance of an existing home and can help identify upgrade opportunities. BASIX is usually connected to design approval, while Home Energy Ratings are connected to existing homes, disclosure, retrofit planning and performance improvement.
BASIX stands for Building Sustainability Index. It is the NSW sustainability assessment pathway for residential development. BASIX covers water, energy use and thermal performance and applies to new residential development, renovations over $50,000 and swimming pools or spas of 40,000 litres or more.
A BASIX Certificate records the sustainability commitments for a project. These commitments may include water efficient fixtures, rainwater tanks, hot water systems, heating and cooling systems, ventilation, insulation, glazing, shading, solar panels and pool or spa details. The certificate is then submitted with the relevant approval documentation, such as a Development Application or Complying Development Certificate.
A Home Energy Rating is an assessment of how an existing home performs. NatHERS is being expanded to include energy ratings for existing homes, after previously being focused on new homes and major renovations. The purpose is to help households understand comfort, energy use, running costs and upgrade opportunities.
A Home Energy Rating Certificate can provide information about where energy is used in the home. It can also include advice and practical tips on how to upgrade the home to improve the rating, use less energy and become more comfortable. This makes it useful for existing homes, retrofit planning, potential sale or lease disclosure and future finance or upgrade programs.
The main difference is the stage and purpose of the assessment. BASIX is usually prepared before approval for a new residential project, qualifying renovation or pool and spa project in NSW. A Home Energy Rating is used to assess an existing home as it currently performs, often to guide upgrades, disclosure, valuation, finance or household decision making.
A simple comparison is:
BASIX usually applies when a NSW residential project needs approval and meets the relevant BASIX triggers. This includes new residential developments, alterations and additions over the threshold, and swimming pools or spas above the relevant volume. The certificate helps show that the proposed design meets water, energy and thermal performance requirements before the project proceeds through approval.
BASIX may be relevant for:
A Home Energy Rating usually applies when the home already exists and someone wants to understand its energy performance. This may be an owner planning upgrades, a buyer comparing homes, a renter reviewing comfort and energy costs, a bank or program considering green finance, or a portfolio owner assessing multiple homes.
Home Energy Ratings may be relevant for:
Yes. An existing home can still need BASIX if building work triggers the BASIX requirements. For example, alterations and additions over $50,000 can require BASIX in NSW. A pool or spa of 40,000 litres or more can also trigger BASIX. In these cases, BASIX is connected to the proposed building work, not simply to the fact that the home already exists.
This is a common point of confusion. If a homeowner is renovating, they may need BASIX for the approval pathway. If they are trying to understand how the current home performs and what upgrades would improve comfort or energy use, they may be looking for a Home Energy Rating instead.
Yes. A renovation may need both, but for different reasons. BASIX may be required because the renovation triggers NSW approval requirements. A Home Energy Rating may be useful because the owner wants to understand the current performance of the existing home and choose upgrades that make the most difference.
For example, BASIX may help define minimum compliance commitments for an alteration or addition, while a Home Energy Rating may help identify whether insulation, draught sealing, glazing upgrades, heating and cooling improvements, solar or other measures would improve comfort and reduce energy use across the whole existing home.
Home Energy Ratings sit within the broader expansion of NatHERS into existing homes. NatHERS explains that Australian governments are working together to deliver energy ratings for existing homes, expanding a scheme that was previously focused on new homes and major renovations. This shift is intended to make home performance easier to understand across Australia.
This matters because many Australian homes were built before modern energy performance expectations. A Home Energy Rating can help translate building performance into clearer information for households, buyers, renters and upgrade programs. It can also support a more structured approach to improving the existing housing stock over time.
A BASIX assessment produces a BASIX Certificate. This certificate records the project commitments that need to be submitted with approval documents and then carried through the design and construction process. The certificate is linked to the proposed building work and should match the plans and specifications.
A Home Energy Rating produces information about the existing home’s performance. A Home Energy Rating Certificate can help explain where energy is used and can include advice and practical upgrade tips. Rather than setting approval commitments for a proposed design, it helps people understand the current home and possible improvement pathways.
The right assessment depends on what you are trying to do. If you are lodging a NSW residential development application or complying development certificate, BASIX may be required. If you are assessing an existing home to understand comfort, energy use and upgrade opportunities, a Home Energy Rating may be more relevant.
Certified Energy prepares BASIX Certificates for NSW residential development and Home Energy Ratings for existing homes. If you are unsure which pathway applies, our team can review the project type, property status, approval pathway and available documentation before confirming the likely next step.
This is especially useful for renovations, existing homes, green upgrade programs, resale preparation, portfolio assessments and projects where the distinction between approval compliance and existing home performance is not immediately clear.
Send your available project details to Certified Energy and our team can confirm whether your property needs BASIX, a Home Energy Rating or both.
Request a ReviewBASIX is the NSW sustainability assessment pathway for residential development approvals. It applies to new residential developments, renovations over $50,000 and pools or spas of 40,000 litres or more. A Home Energy Rating is used to assess the energy performance of an existing home and can help owners, buyers and renters understand upgrade opportunities.
No. A Home Energy Rating is not the same as BASIX. BASIX is linked to NSW residential development approval, while Home Energy Ratings are part of the expanded NatHERS pathway for understanding the energy performance of existing homes.
An existing home may need BASIX if it is undergoing residential building work that triggers BASIX requirements, such as renovations over $50,000. A Home Energy Rating may be used to assess the existing home’s current energy performance and identify practical upgrade opportunities.
Yes. A renovation may need BASIX if it triggers NSW approval requirements, while a Home Energy Rating may be useful for understanding the current performance of the existing home and planning upgrades. The correct pathway depends on the project scope and purpose of the assessment.