BASIX can be required whether a residential project in NSW is submitted through a Development Application or a Complying Development Certificate pathway. The certificate itself still addresses water, energy use and thermal performance, but the approval pathway changes who reviews the application, how the documents are lodged and how quickly the project may need to be ready for assessment.
BASIX and NatHERS are often mentioned together in NSW residential projects, but they are not the same thing. BASIX is the NSW sustainability assessment framework used for residential development approvals. NatHERS is a national rating scheme used to assess the thermal performance of a home, including how much heating and cooling the dwelling is likely to need.
Yes, a BASIX Certificate may need to be amended, revised or replaced if the project changes after the original certificate has been prepared. This can happen when the design changes, the glazing changes, the insulation strategy changes, a hot water system is updated, a rainwater tank commitment is altered or the plans no longer match the certificate commitments.
If your project does not meet BASIX requirements, it usually means the assessment cannot be finalised until something is adjusted. This does not necessarily mean the project is rejected or that the design cannot proceed. In most cases, the assessor needs to review the BASIX inputs, identify which target is not being met and work with the project team to find a practical way forward.
The time needed to prepare a BASIX Certificate in NSW depends on the project type, the quality of the available documentation and whether additional assessment work is required. A simple project with complete plans can often move quickly. A more complex project, incomplete documentation, large areas of glazing or a required NatHERS thermal comfort assessment can take longer to review and finalise.
To prepare a BASIX Certificate in NSW, an assessor needs enough project information to understand the design, building fabric, water commitments, energy systems and thermal performance pathway. The exact documents required depend on the project type, but most BASIX assessments begin with the architectural drawings and then move into the details that affect water, energy and thermal comfort compliance.
Home Energy Rating
A home energy rating can be useful for more than one type of person or project.
Homeowners, buyers, sellers, landlords, renters, renovators, property managers, designers and real estate professionals may all want to understand how an existing home performs for energy efficiency, comfort and upgrade potential.
The important distinction is that a rating can be requested by different parties, but a formal assessment usually needs appropriate property access, the right assessment pathway and a qualified assessor where a certificate is required.
Quick Answer
A home energy rating may be requested by homeowners, buyers, sellers, landlords, renters, renovators, real estate professionals, property managers, designers or project teams, depending on the purpose of the assessment and access to the property.
The most common reasons are renovation planning, comfort improvement, sale or lease preparation, upgrade prioritisation, property due diligence, portfolio review or future disclosure readiness.
For NatHERS Existing Homes, any formal Home Energy Rating Certificate must be generated by an accredited existing homes assessor. The enquiry can start with property details, but the assessment itself must follow the relevant pathway.
Homeowners are one of the most natural groups to request a rating. They may want to understand why the home feels hot, cold, draughty or expensive to run.
A rating can help a homeowner understand the current performance of the dwelling and identify which upgrades may be worth considering first. This may include insulation, glazing, shading, heating and cooling, hot water, solar, batteries or staged renovation measures.
For a broader definition, see What Is a Home Energy Rating for Existing Homes?
Buyers may be interested in a home energy rating because comfort and running costs are not always obvious during an inspection.
A home may present well visually but still have poor insulation, weak glazing, inefficient systems or rooms that overheat or stay cold. A rating can help a buyer understand the likely performance of the property before making longer-term decisions.
In practice, a buyer may need permission from the owner or agent before a formal assessment can occur, because property access is usually required.
Sellers may request a home energy rating to better understand how the home performs before it is listed for sale.
This may be useful where the home has been upgraded, renovated, insulated, electrified or fitted with solar and batteries. A rating can help make energy performance easier to explain in a structured way.
It may also become more relevant as home energy rating disclosure pathways continue to develop in Australia. For the current position, see Are Existing Home Energy Ratings Mandatory in Australia?
Landlords may request a home energy rating to better understand the comfort and performance of a rental property.
This can be helpful when planning upgrades, preparing for future disclosure expectations, improving tenant comfort or reviewing the long-term condition of a property portfolio.
For rental properties, access arrangements may need to be coordinated with the tenant, property manager or managing agent.
Renters may want to understand a home’s energy performance, especially where the property is uncomfortable, expensive to heat or cool, or difficult to live in during extreme weather.
However, a formal assessment will usually require property access and may involve areas or systems that are controlled by the owner or managing agent.
This means renters may be able to ask about a rating or encourage one, but the practical assessment pathway usually needs owner or agent approval.
Renovators can use a home energy rating to understand the existing dwelling before committing to upgrade decisions.
This can help identify whether the priority is insulation, windows, shading, draught sealing, heating and cooling, hot water, solar, batteries or a broader staged retrofit pathway.
For renovation projects, a rating may also help design teams understand how the existing home performs before proposed changes are locked in.
Architects, building designers, builders and project teams may request home energy rating support when working on an existing dwelling.
This is particularly useful where a project needs to understand real built performance before making design or construction decisions. It can also help separate existing-home performance advice from new-home NatHERS compliance.
For that distinction, see NatHERS Existing Homes vs New Home NatHERS Assessments.
Real estate agents and property managers may become involved in home energy ratings where a seller, landlord, buyer, renter or property owner wants clearer performance information.
They may help coordinate access, provide property information, communicate with owners or tenants, and help explain why a rating is being requested.
As disclosure pathways develop, property professionals may need to become more familiar with how ratings work and when they are useful.
It is important to separate who can request a rating from who can issue the formal certificate.
A homeowner, buyer, seller, landlord, renter or project team may be interested in a rating. But for NatHERS Existing Homes, a Home Energy Rating Certificate can only be generated by an accredited existing homes assessor.
This is why it is useful to confirm the pathway early rather than assuming that any general energy review will produce the same outcome.
A home energy rating is most useful when it supports a real decision.
Common times to request a rating include:
The earlier the rating is considered, the easier it may be to avoid rushed or poorly sequenced upgrade decisions.
A request does not need to begin with perfect documentation. However, it is helpful to prepare the information that is available.
Useful information may include:
For a full preparation checklist, see What Information Do You Need for a Home Energy Rating?
A home energy rating may be requested by homeowners, buyers, sellers, landlords, renters, renovators, real estate professionals, property managers, designers or project teams, depending on the purpose of the assessment and access to the property.
Yes. Homeowners can request a home energy rating to understand comfort, energy performance, upgrade priorities, renovation planning or future disclosure readiness.
A buyer may want energy performance information before purchasing, but the assessment will usually require appropriate property access and permission. The practical pathway depends on the sale process and the cooperation of the owner or agent.
Yes. Landlords and rental property owners may request a home energy rating to understand comfort, running cost factors, upgrade opportunities and possible future disclosure or rental property performance expectations.
A renter may be interested in a home energy rating, but a formal assessment will usually require property access and the owner or managing agent’s approval.
A NatHERS existing Home Energy Rating Certificate can only be generated by an accredited existing homes assessor.
Assessment Pathway Review
Send property details to confirm whether a home energy rating pathway is suitable.
Home Energy Rating
A home energy rating may provide a star rating, but the star rating is only one part of the wider performance picture.
For many homeowners, the idea of a star rating is familiar because NatHERS has long used stars to describe the thermal performance of new homes. As NatHERS expands into existing homes, star rating language is also becoming relevant to established dwellings.
The key is to understand what the star rating does, what it does not measure, and how it differs from broader whole-of-home energy performance.
Quick Answer
Under NatHERS, homes can receive a thermal star rating from 0 to 10. A higher star rating generally means the home is expected to be more comfortable and cheaper to keep comfortable, because it should need less heating and cooling.
For existing homes, the rating may also sit alongside broader home energy performance information. This can include whole-of-home energy considerations such as heating and cooling systems, hot water, lighting, appliances, solar PV and batteries.
The star rating is useful, but it should not be treated as the only thing that matters. A home may also need practical upgrade advice, system review and careful interpretation of what the rating means for comfort, running costs and future improvements.
The NatHERS star rating describes the thermal performance of a home. It helps explain how much heating and cooling the dwelling is likely to need to remain comfortable in its climate.
A higher star rating generally means the home is better at staying comfortable with less energy for heating and cooling. A lower star rating generally means the home may be more expensive or difficult to keep comfortable.
For an existing home, this can be useful because it gives the homeowner a clearer performance signal than simply saying the home feels hot, cold or expensive to run.
The thermal star rating is influenced by the way the home is designed, built and exposed to its climate.
Key factors may include:
In existing homes, some of these details may be easy to identify. Others may need to be confirmed through plans, site observations, photos, homeowner information or assessment assumptions.
No. The thermal star rating and whole-of-home performance are related, but they are not the same thing.
The thermal star rating focuses on the building’s heating and cooling needs. It is mainly about how well the dwelling itself manages heat gain, heat loss and thermal comfort.
Whole-of-home performance may also consider major energy systems and generation, such as hot water, heating and cooling systems, lighting, appliances, solar PV and batteries. This gives a broader view of energy use across the home.
A star rating is a useful summary, but it does not explain everything on its own.
For example, two homes may have similar thermal ratings but very different hot water systems, appliance loads, solar systems or battery storage. One may have strong building fabric but inefficient systems. Another may have solar panels but still overheat because of poor shading or glazing.
This is why a home energy rating should be interpreted with the wider assessment information, not only the star number.
The rating language may be similar, but the assessment context is different.
A new home NatHERS assessment usually rates a proposed design before it is built. It is commonly used for compliance and design-stage decision-making.
An existing home rating assesses a dwelling that already exists. It must respond to real construction, previous renovations, installed systems, missing documentation and the current condition of the home.
For a detailed comparison, see NatHERS Existing Homes vs New Home NatHERS Assessments.
The 7 Star conversation is mainly connected to new-home energy efficiency standards under the National Construction Code and state implementation.
Existing home ratings are different. They help assess current performance and identify possible upgrades, but they should not be confused with a new-home compliance requirement.
A homeowner may still want to improve the rating of an existing home, but the assessment should be understood as a performance and improvement pathway, not simply a new-build compliance test.
A Home Energy Rating Certificate may show the home’s assessed energy performance and provide information that can help guide comfort and upgrade decisions.
The exact certificate format can depend on the assessment pathway and rollout stage. In the NatHERS existing homes trial, participating households received a trial certificate that included a star rating out of 10 and a home energy rating out of 100.
For homeowners, the most useful approach is to treat the certificate as a starting point for understanding performance, not as a replacement for practical assessment advice.
Yes. A rating can help identify where an existing home may be improved.
Possible upgrade areas may include:
The important question is sequencing. A good assessment can help a homeowner understand which measures should be considered first, rather than treating every upgrade as equal.
A higher star rating generally indicates that the home should need less heating and cooling to remain comfortable. This can support lower running costs, especially when compared with a similar home in the same climate and usage pattern.
However, energy bills are also affected by household behaviour, tariffs, occupancy, appliances, pool equipment, work-from-home patterns, thermostat settings and how systems are used.
This is why the rating should be read as performance information, not as a guarantee of a specific bill amount.
To produce a rating, the assessor needs enough information about the dwelling and its systems. For existing homes, this may include property details, available plans, site data, photos, renovation history, insulation details and system information.
Useful preparation may include:
For a practical checklist, see What Information Do You Need for a Home Energy Rating?
As NatHERS expands into existing homes, star ratings help bring a familiar performance language into established dwellings.
This can help homeowners, buyers, sellers, landlords and property professionals understand a home’s performance more clearly. It may also support future disclosure conversations as rating pathways continue to develop.
For more context, see What Is NatHERS Existing Homes?
A home energy rating may provide a star rating, depending on the assessment pathway. Under NatHERS, homes can receive a thermal star rating from 0 to 10, where a higher rating generally means the home is more comfortable and cheaper to run.
The NatHERS thermal star rating describes how well the home performs thermally. It reflects how much heating and cooling the home is likely to need to remain comfortable, based on features such as layout, orientation, insulation, windows, shading and climate.
No. The thermal star rating and whole-of-home energy performance are related but not the same. The star rating focuses on thermal performance, while whole-of-home performance may also consider appliances, hot water, solar, batteries and other energy uses.
A higher star rating generally indicates a home should need less heating and cooling to remain comfortable. However, actual energy bills also depend on household behaviour, tariffs, occupancy, appliances and system use.
An existing home may be able to improve its rating through upgrades such as insulation, draught sealing, window improvements, shading, efficient heating and cooling, hot water upgrades, solar or batteries. The best sequence depends on the home.
7 Star requirements are mainly connected to new-home energy efficiency standards under the National Construction Code. Existing home ratings help assess current performance and upgrade potential, but they should not be confused with new-home compliance requirements.
Rating Pathway Advice
Certified Energy can help explain what rating output applies to your assessment pathway.
Home Energy Rating
A home energy rating measures how a dwelling performs as a home, not just how much energy appears on a bill.
For existing homes, the assessment may look at the building fabric, thermal comfort, windows, insulation, heating and cooling, hot water, solar, batteries and potential upgrade opportunities.
The purpose is to help homeowners, buyers, sellers, landlords and project teams understand how an established dwelling performs now, and what may improve its comfort and energy efficiency over time.
Quick Answer
A home energy rating measures how an existing dwelling performs for energy efficiency, comfort and likely energy use. It can help explain how well the home manages heat, cold, ventilation, appliances and energy demand.
The assessment may consider the building fabric, insulation, glazing, shading, orientation, heating and cooling, hot water, lighting, solar PV, batteries and other major energy-related features.
A rating is not simply a review of past energy bills. Bills can be affected by occupancy, behaviour and tariffs. A home energy rating is more focused on the home itself and how it is likely to perform.
A home energy rating is most useful when it looks at the home as a connected system. The walls, roof, floor, windows, shading and installed systems all affect comfort and energy demand.
For example, an efficient air conditioner may still struggle in a home with poor insulation, large unshaded windows or major draughts. Solar panels may reduce grid electricity use, but they do not necessarily solve overheating, winter heat loss or poor thermal comfort.
This is why a home energy rating for existing homes needs to consider both the building and the systems that support it.
The building fabric is the physical shell of the home. It includes the elements that separate inside from outside and influence how quickly heat enters or leaves the dwelling.
This may include:
Building fabric matters because it often determines how much heating or cooling the home needs before any appliance is even switched on.
Insulation is one of the main factors that can influence a home’s heating and cooling needs. A home with poor or missing insulation may lose heat quickly in winter and gain heat quickly in summer.
The assessment may consider insulation in:
In existing homes, insulation is not always easy to verify. The assessor may need to work with available plans, photos, site observations, renovation records and permitted assumptions.
Windows can have a major effect on comfort and energy use. They influence heat gain, heat loss, daylight, ventilation and exposure to sun.
A home energy rating may consider:
This is especially important in Australian homes where summer heat gain, winter heat loss and sun exposure can vary significantly by climate and orientation.
Thermal performance is one of the clearest parts of a home energy rating. It helps explain how much heating or cooling a home is likely to need to remain comfortable.
This is influenced by the design and construction of the home, not only by the appliances installed. A well-insulated, well-shaded home may need less active heating and cooling. A poorly sealed or poorly insulated home may need more energy to remain comfortable.
For existing homes, this can help explain why some rooms are difficult to heat, why certain spaces overheat, or why energy use remains high even after appliance upgrades.
Depending on the rating pathway, a home energy rating may also consider major fixed systems that contribute to household energy use.
These may include:
This is where the assessment starts to move beyond the shell of the building and into whole-of-home energy performance.
Solar PV and batteries can influence how much energy a home draws from the grid. Depending on the assessment pathway, they may be included as part of whole-of-home performance.
This does not mean that solar alone makes a home comfortable or efficient. A home with solar panels can still have poor insulation, overheating, draughts or high heating and cooling demand.
The rating is most useful when solar and batteries are considered alongside the building fabric and installed systems.
Many homeowners first become interested in a home energy rating because the home feels uncomfortable. Some rooms may overheat. Others may stay cold. Some areas may be draughty, damp or difficult to condition.
Useful comfort information may include:
This context helps connect the rating to the lived experience of the home.
One of the practical benefits of a home energy rating is that it can help identify where improvements may be most useful.
Possible upgrade areas may include:
The value is not just the list of possible upgrades. It is the sequencing. A rating can help homeowners understand whether the first step should be improving the building fabric, replacing systems, reviewing solar or planning upgrades as part of a renovation.
Energy bills can be useful context, but they do not tell the full story of the home. Bills are affected by household size, behaviour, tariffs, climate, appliance use and whether people work from home.
Two homes with similar bills may perform very differently. One may be efficient but heavily occupied. Another may be inefficient but used lightly. A home energy rating is intended to give a more structured understanding of the dwelling itself.
This is why the assessment focuses on physical features, systems and likely performance rather than treating a bill as the rating.
Different home energy rating pathways may have different inputs, certificate formats, software requirements and reporting outputs.
NatHERS Existing Homes, Residential Efficiency Scorecard and other home energy assessment approaches may not all present information in exactly the same way. The important point is to confirm which pathway applies before assuming what will be measured or reported.
For the NatHERS pathway, see What Is NatHERS Existing Homes?
Because a home energy rating measures the dwelling and its systems, the assessment is easier when useful information is available.
Helpful information may include:
For a practical preparation checklist, see What Information Do You Need for a Home Energy Rating?
A home energy rating measures how a dwelling performs for energy efficiency, comfort and likely energy use. For existing homes, it may consider the building fabric, insulation, windows, shading, heating and cooling, hot water, appliances, solar, batteries and upgrade potential.
Yes. Insulation is one of the key elements that can influence a home energy rating. The assessment may consider ceiling, roof, wall and floor insulation where this information is available, observable or able to be assessed under the relevant pathway.
Yes. A home energy rating may consider heating and cooling needs, installed systems and how the dwelling manages heat gain and heat loss. This helps explain comfort and likely energy demand.
Depending on the rating pathway, solar PV and batteries may be considered as part of whole-of-home energy performance. These systems can influence how much energy the home uses from the grid.
A home energy rating is not the same as an energy bill review. Bills are affected by tariffs, occupancy and behaviour. The rating focuses more directly on the dwelling, its systems and its likely performance.
Yes. A home energy rating can help identify possible upgrade opportunities, such as insulation improvements, glazing changes, draught sealing, more efficient systems, solar, batteries or staged renovation measures.
Assessment Preparation
Prepare available property details so the assessment pathway can be reviewed.
NatHERS Existing Homes
NatHERS Existing Homes is the expansion of Australia’s Nationwide House Energy Rating Scheme into homes that have already been built.
For many years, NatHERS has been most familiar as a new-home rating system used during design and compliance. The existing homes pathway extends the same national rating language into established dwellings, helping homeowners and property teams understand how a real home performs now.
This matters because an existing home is not a proposed design. It has already been built, occupied, altered and maintained over time. A NatHERS Existing Homes assessment is intended to help make that real performance easier to understand.
Quick Answer
NatHERS Existing Homes is the expansion of the Nationwide House Energy Rating Scheme into existing dwellings. It helps assess the current energy performance, comfort and improvement potential of homes that have already been built.
It is different from a standard new home NatHERS assessment. New home NatHERS is usually used before construction to assess a proposed design. NatHERS Existing Homes looks at a real dwelling as it stands today.
For homeowners, buyers, sellers, landlords, designers and property professionals, the pathway can help translate building performance into clearer information about comfort, energy use and possible upgrades.
Australia already has a long-established rating system for new homes. But most homes in Australia have already been built, and many were constructed before current energy efficiency expectations were introduced.
Existing homes can be difficult for households to understand. A home may look well presented but still perform poorly in summer or winter. It may have high running costs, weak insulation, inefficient systems, poor glazing or comfort problems that are not obvious during a standard property inspection.
NatHERS Existing Homes gives a more consistent way to describe this performance. It helps shift the conversation from guesswork toward a structured assessment of how the home actually performs.
A Home Energy Rating is the broader consumer-facing idea: a way to understand how an existing home performs for energy use, comfort and potential upgrades.
NatHERS Existing Homes is one of the key national pathways supporting this shift. It sits within the NatHERS framework and provides a more consistent language for rating existing dwellings.
For a broader definition, see What Is a Home Energy Rating for Existing Homes?
A NatHERS Existing Homes assessment looks at the dwelling as it exists, not only as it may have been designed. The exact information required depends on the assessment pathway, available documentation and the condition of the home.
The assessment may consider:
The purpose is not only to produce a number. A useful assessment can help a homeowner understand what is influencing performance and where improvements may be most effective.
The core difference is timing and purpose.
New home NatHERS usually assesses a proposed design before construction. It is commonly used for compliance, certification and design-stage decision-making. The assessor works from drawings, specifications and construction details.
NatHERS Existing Homes assesses a dwelling that has already been built. It must respond to real construction, previous renovations, installed systems, missing documentation and the actual condition of the home.
For a detailed comparison, see NatHERS Existing Homes vs New Home NatHERS Assessments.
NatHERS existing Home Energy Rating certificates can only be generated by an accredited existing homes assessor.
This distinction matters because existing homes require specific assessment processes. The assessor may need to deal with incomplete documentation, site data, assumptions, existing systems and real-world construction conditions.
For clients, this means the right pathway should be confirmed before assuming that a standard new-home NatHERS assessment is suitable.
Existing home energy ratings are not yet mandatory across Australia as a universal requirement. However, disclosure pathways are developing, and requirements may vary by jurisdiction, program or transaction type over time.
This is why the wording needs to be careful. NatHERS Existing Homes should be understood as an emerging and expanding assessment pathway, not as a blanket requirement for every existing home today.
For a fuller explanation, see Are Existing Home Energy Ratings Mandatory in Australia?
NatHERS Existing Homes may be useful for homeowners who want to understand how their home performs and what upgrades may be worth considering.
It may also be relevant for buyers, sellers, landlords, rental property owners, renovation teams, real estate professionals and organisations reviewing residential portfolios.
The pathway is especially useful where a client needs to understand an established dwelling rather than a proposed new design.
The required information depends on the home and assessment pathway. As a starting point, it is helpful to prepare the property address, available plans, renovation history, photos and details of major systems.
Useful information may include:
If the documentation is incomplete, the assessment may still be possible. The pathway can be reviewed based on the information that is available.
One common misunderstanding is that NatHERS Existing Homes is simply the same as a new home NatHERS assessment. It is not. The existing homes pathway deals with real dwellings, not only proposed designs.
Another misunderstanding is that the rating only relates to energy bills. Bills can be influenced by behaviour, tariffs and occupancy. The assessment is more useful when it helps describe the dwelling’s performance and possible improvement opportunities.
A third misunderstanding is that every existing home must already have a rating. This is not the current national position. The disclosure landscape is developing, but it should not be overstated.
A fourth misunderstanding is that a rating automatically means one specific upgrade is required. In practice, the value of the assessment is that it can help clarify the home’s performance and support better decision-making.
For homeowners, NatHERS Existing Homes can help turn general concerns about comfort and energy use into clearer performance information.
For renovators and design teams, it can help identify existing performance issues before upgrade decisions are locked in.
For sellers, landlords and property professionals, it may become increasingly relevant as home energy disclosure pathways develop.
For consultants, the key is to separate the existing homes pathway from new-home compliance and guide clients toward the correct assessment type.
NatHERS Existing Homes is the expansion of the Nationwide House Energy Rating Scheme into established dwellings. It helps assess the energy performance, comfort and upgrade potential of homes that have already been built.
No. New home NatHERS usually assesses a proposed residential design before construction for compliance purposes. NatHERS Existing Homes assesses a dwelling that already exists and focuses on current performance and improvement opportunities.
A NatHERS Existing Homes assessment may consider the dwelling’s construction, insulation, glazing, shading, heating and cooling systems, hot water, appliances, solar, batteries, ventilation, comfort and possible upgrade opportunities.
NatHERS existing Home Energy Rating certificates can only be generated by an accredited existing homes assessor.
Existing home energy ratings are not yet mandatory across Australia as a universal requirement. Disclosure pathways are developing, and requirements may vary over time by jurisdiction, program or transaction type.
The expansion helps households better understand the performance of homes that have already been built, including comfort, energy use and potential upgrades.
Existing Home Assessment Pathways
Certified Energy can help clarify whether NatHERS Existing Homes is the right pathway for your property.
