Home Energy Rating Preparation

What Information Do You Need for a Home Energy Rating?

A home energy rating is easier to review when the right property information is available at the start.

For an existing home, the assessment is based on the dwelling as it currently stands. That means property details, available plans, photos, renovation history and information about installed systems can all help the assessor understand the home more clearly.

You do not need to have perfect records before making an enquiry. But preparing the information you do have can make the quote and assessment pathway easier to confirm.

Why the right information matters

A home energy rating is not based only on a quick visual impression. It depends on the physical features of the dwelling, the installed systems and the way the home is likely to perform in its climate.

For existing homes, the information can be less tidy than it is for a new build. Plans may be missing. Renovations may have changed the home. Insulation may have been added without clear records. Heating, cooling, hot water and solar systems may have been replaced over time.

The more clearly this information is provided, the easier it is to confirm the right existing home energy rating pathway and understand what further data collection may be needed.

Start with basic property details

The first information to prepare is simple but important. It helps identify the property, dwelling type and likely assessment context.

Useful property details include:

• property address
• dwelling type, such as house, townhouse, apartment or duplex
• number of storeys
• approximate year of construction
• approximate floor area, if known
• whether the home has been extended or altered
• whether the home is owner-occupied, rented or being prepared for sale
• why the rating is being requested

The reason for the rating matters. A homeowner planning upgrades may need a different review pathway from a property owner preparing for disclosure, sale, lease or program participation.

Provide any available plans or drawings

Plans are helpful because they can show the dwelling layout, room sizes, orientation, extensions and construction details. They can also make it easier to understand parts of the home that are difficult to inspect visually.

Useful documents may include:

• floor plans
• site plans
• elevations
• sections
• renovation drawings
• extension plans
• window or glazing schedules, if available
• previous energy assessment documents, if available

Many existing homes do not have complete original plans. That is common. If plans are missing, the enquiry can still begin, but the assessor may need to rely more on site data, photos, observations and the assessment rules. For more detail, see Can you get a rating without original plans?

Photos can help the assessment pathway review

Photos do not replace a proper assessment, but they can help clarify the property before a quote or pathway review is confirmed.

Helpful photos may include:

• front, rear and side elevations of the home
• main living areas
• rooms that are too hot or too cold
• windows and external shading
• ceiling, roof or subfloor access points, where safely visible
• heating and cooling units
• hot water system
• solar inverter, panels or battery equipment
• switchboard or major electrical upgrade areas, if relevant
• any obvious draught, moisture or comfort issue areas

Do not enter unsafe areas to take photos. If roof, ceiling or subfloor spaces are not safely accessible, this can be noted instead.

Include renovation and upgrade history

Renovation history can change how an existing home performs. An older dwelling may have new windows, added insulation, a renovated roof, upgraded air conditioning or an extension built to a different standard from the original home.

Useful renovation information may include:

• year of renovation or extension works
• which rooms or areas were changed
• whether insulation was added
• whether windows or doors were replaced
• whether the roof was replaced or upgraded
• whether heating, cooling or hot water was changed
• whether solar PV or batteries were installed

Even informal information can be useful. If you know that the ceiling was insulated around five years ago, or that the rear extension was built in the 1990s, include that in the enquiry.

Share what you know about insulation

Insulation has a major influence on thermal performance, but it is often one of the least clearly documented parts of an existing home.

If known, provide information about:

• ceiling insulation
• roof insulation
• wall insulation
• floor insulation
• insulation installed during renovations
• insulation product details or receipts
• areas where insulation may be missing or damaged

It is normal not to know all of this. The assessor can advise what needs to be observed, recorded or treated as uncertain within the assessment process.

Prepare heating, cooling, hot water and solar details

A home energy rating can consider more than the building fabric. Installed systems may also affect the home’s performance, running costs and upgrade opportunities.

Useful system information includes:

• heating system type and location
• cooling system type and location
• hot water system type
• approximate system age, if known
• photos of model numbers or labels
• solar PV system size, if known
• battery details, if installed
• major fixed appliance details, where relevant
• recent electrification upgrades

If you are unsure what system you have, photos are often enough to begin the review. The details can be clarified during the assessment process.

Describe any comfort issues

Comfort issues can help point the assessment toward real performance concerns. They do not replace modelling or data collection, but they provide useful context.

Useful comfort information may include:

• rooms that overheat in summer
• rooms that stay cold in winter
• areas affected by draughts
• rooms with glare or too much sun exposure
• rooms that are difficult to heat or cool
• condensation or moisture concerns
• whether the home relies heavily on air conditioning

This type of information helps connect the technical assessment to the lived experience of the home.

What if you do not have all the information?

Most homeowners do not have every detail available at the start. This is especially true for older homes, inherited properties, investment properties or homes that have been renovated by previous owners.

Missing information does not automatically prevent an enquiry. It simply means the assessor needs to confirm what can be determined from available documents, photos, site data, observations and the assessment rules.

Start with what you have. The assessment pathway can then be reviewed and any critical gaps can be identified before the assessment proceeds.

Quick preparation checklist before requesting a quote

Before requesting a quote, it is helpful to prepare a simple folder of available information.

• property address
• reason for requesting the rating
• available plans or drawings
• photos of the home
• renovation or extension history
• known insulation information
• heating and cooling details
• hot water system details
• solar PV or battery details
• known comfort issues
• preferred timing or access constraints

This does not need to be perfect. A clear starting point is usually enough for the assessment pathway to be reviewed.

FAQs

What information do you need for a home energy rating?

For a home energy rating, useful information includes the property address, dwelling type, available plans, renovation history, insulation details, heating and cooling systems, hot water, solar, batteries, photos and known comfort issues.

Do I need original plans for a home energy rating?

Original plans are helpful but not always essential. Many existing homes do not have complete documentation. The assessment process can often work with available drawings, site data, photos, observations and reasonable assumptions where permitted.

What photos are useful for a home energy rating?

Useful photos may include external elevations, windows, shading, heating and cooling systems, hot water systems, solar equipment, insulation access points, roof or subfloor areas where safely visible, and rooms with known comfort issues.

Do I need to know what insulation is in my home?

Insulation information is useful, but many homeowners do not know the full details. If known, provide insulation type, location and upgrade history. If not known, the assessor may identify what can be observed or what needs to be treated as uncertain.

What systems should I provide details for?

Provide details for heating and cooling systems, hot water, solar PV, batteries, major fixed appliances and any recent energy upgrades. Photos of model numbers or system labels can be helpful.

Can I request a home energy rating before I have all the information?

Yes. You can usually begin with the property address, available plans or photos, and the reason for the rating. The assessor can then confirm what additional information is needed before the assessment proceeds.

Quote Preparation

Preparing to request a home energy rating?

Prepare your available plans, photos and property details before requesting a quote. Certified Energy can then review the likely assessment pathway and confirm what else may be needed.

Request a quote for a home energy rating

NatHERS Existing Homes

How Does a NatHERS Existing Home Assessment Work?

A NatHERS existing home assessment helps explain how an established dwelling performs as it stands today.

Unlike a new home NatHERS assessment, which is usually based on proposed design documentation, an existing home assessment responds to the real dwelling. It looks at the current construction, installed systems, available documentation and observable performance issues.

For homeowners, designers, builders and property professionals, the process becomes much easier to understand when it is broken into stages: property details, site data collection, assessment input, modelling, review and reporting.

Why the assessment process matters

Existing homes are more complex than proposed designs because the building has already been constructed, lived in, altered and maintained over time. The assessment process needs to work with real conditions rather than ideal design intent.

Some homes have complete drawings and construction details. Others have very little documentation. Some have been renovated several times, with insulation, glazing, appliances or heating systems changed along the way. This makes data collection and review an important part of the assessment.

A clear process helps homeowners understand what is being assessed, why the information is needed and how the final rating can support better decisions.

Step 1: Property details are reviewed

The first stage is usually a review of the property and the purpose of the assessment. This helps confirm whether a NatHERS Existing Homes assessment is the right pathway.

Useful starting information may include:

• property address
• dwelling type
• approximate age of the home
• number of storeys
• available floor plans or drawings
• renovation or extension history
• known comfort issues
• reason for seeking the assessment

The reason for the assessment matters. A homeowner planning upgrades may need different advice from a property team preparing for future disclosure, portfolio review or program participation.

Step 2: Available documentation is checked

If plans, specifications or renovation records are available, they can help the assessment process. They may show wall construction, glazing changes, extension areas or parts of the home that are difficult to verify visually.

However, many existing homes do not have complete documentation. This does not necessarily prevent an assessment, but it does affect how information is collected, recorded and reviewed.

A good assessment process should identify what is known, what can be observed and where assumptions may be required. This is one reason existing home assessment is different from new home NatHERS, where the assessor usually works from design documentation before construction.

Step 3: On-site data is collected

On-site data collection is the part of the process that makes an existing home assessment practical and grounded. The dwelling needs to be recorded as it actually exists, not only as it may have been designed many years earlier.

The site data collection process may record:

• dwelling layout and zones
• room dimensions or geometry
• orientation
• window size, type and location
• external shading and exposure
• roof, wall and floor construction where identifiable
• visible insulation or known insulation details
• heating and cooling systems
• hot water system type
• lighting and fixed appliances
• solar PV and battery systems
• ventilation features
• observable draught or comfort issues

This stage may involve a trained assessor or, depending on the delivery model, a trained data collector working with an assessor. The important principle is that the information needs to be collected consistently enough to support a reliable rating.

Step 4: The data is entered into the assessment pathway

Once the property data has been collected, it needs to be entered into the relevant assessment process. This is where the dwelling information becomes structured enough to support modelling and rating.

For existing homes, this step needs careful handling because not every input will be known with the same level of certainty. Some information may be measured. Some may be documented. Some may need to be based on approved defaults or reasonable assumptions, depending on the assessment rules.

The quality of this stage depends on how clearly the data has been collected and how well the assessor understands existing-home construction, energy systems and assessment requirements.

Step 5: Thermal modelling and energy performance are reviewed

The assessment data is then used to calculate the home’s energy performance. This may include thermal performance, comfort-related outcomes and whole-of-home energy considerations such as major appliances, solar and batteries.

This stage connects the observed dwelling to a performance rating. It helps translate building features into a clearer understanding of how the home is likely to behave in different seasons and conditions.

For a deeper explanation of how these assessment pathways differ from new home compliance, see NatHERS Existing Homes vs New Home NatHERS Assessments.

Step 6: Questions and assumptions may be clarified

Existing homes often raise questions during review. An assessor may need to clarify whether an extension was insulated, whether a window has been replaced, whether a system is still in use or whether documentation matches the actual dwelling.

This review stage is important because a rating should not simply be generated from incomplete or poorly understood information. Where uncertainty exists, it should be handled consistently and carefully within the assessment rules.

For homeowners, this may mean answering follow-up questions, providing photos, confirming system details or supplying any missing information that becomes relevant during the review.

Step 7: The rating and reporting are prepared

The final stage is reporting. Depending on the assessment pathway, this may include a Home Energy Rating Certificate and supporting information about the dwelling’s performance.

A useful report should help the property owner understand more than a single rating. It should explain what the rating means in practical terms and how it may relate to comfort, energy use, upgrade planning or disclosure readiness.

The report can become a decision-making tool. It may help a homeowner decide whether to improve insulation, replace heating and cooling, address draughts, upgrade hot water, review solar and battery options or stage renovation works more carefully.

What should homeowners prepare?

A homeowner does not need to have perfect records before requesting an assessment. However, the process is easier when basic information is available.

Useful information may include:

• available plans or drawings
• renovation or extension details
• insulation upgrades already completed
• window replacement details
• heating and cooling system details
• hot water system details
• solar PV or battery system details
• known comfort issues in particular rooms
• recent energy upgrade information

Even partial information can be helpful. The assessor can then identify what is already known and what needs to be confirmed through data collection or review.

What can the assessment help you decide?

A NatHERS existing home assessment can help turn general energy concerns into a more structured pathway.

It may support decisions about:

• which energy upgrades should come first
• whether the home needs insulation improvements
• whether glazing or shading should be reviewed
• whether heating and cooling systems are suitable
• whether electrification should be staged
• how solar and batteries fit into the home’s performance
• how a renovation could improve comfort
• how the home may be positioned for future disclosure

For a broader definition of this type of rating, see What Is a Home Energy Rating for Existing Homes?

How long does the process take?

Timing can vary depending on the property, documentation, access, assessment pathway and whether follow-up information is required.

A simple home with clear access and available documentation may be more straightforward. A larger or heavily altered dwelling may take longer because more information needs to be checked and entered carefully.

The best first step is to send the property details, available plans and the reason for the assessment so the correct pathway and likely process can be reviewed.

Common misunderstandings about the process

One misunderstanding is that the assessment is only a visual inspection. Visual observation matters, but the process also involves structured data collection, input, modelling, review and reporting.

Another misunderstanding is that a homeowner must already know every construction detail. In many existing homes, some details are unknown. The process is designed to work with a combination of measured, documented, observed and assessed information.

A third misunderstanding is that the rating automatically tells the homeowner to buy one specific product. A good assessment should support better decision-making, not simply push a single upgrade.

Finally, an existing home assessment should not be confused with new home compliance. For that distinction, see NatHERS Existing Homes vs New Home NatHERS Assessments.

Practical project implications

For homeowners, the assessment can provide a clearer sequence for upgrades rather than a disconnected list of energy ideas.

For architects and designers, it can provide a stronger understanding of the existing dwelling before renovation decisions are locked in.

For builders, it may help identify where energy performance improvements need to be integrated into the work rather than added later.

For property professionals, it can help explain comfort and energy performance in a more structured way as disclosure pathways continue to develop.

For consultants, it helps separate real built performance assessment from proposed design compliance.

FAQs

How does a NatHERS existing home assessment work?

A NatHERS existing home assessment usually begins with property details and available documentation, followed by on-site data collection, assessment input, modelling, review and reporting. The purpose is to assess the real performance of a dwelling that has already been built.

Does a NatHERS existing home assessment require a site visit?

A NatHERS existing home assessment generally requires on-site data collection so the dwelling’s construction, systems, appliances and other relevant features can be recorded. Depending on the delivery model, this may be completed by the assessor or by a trained data collector working with the assessor.

What information is collected during a NatHERS existing home assessment?

The information may include dwelling layout, construction type, insulation, windows, shading, orientation, heating and cooling systems, hot water, lighting, appliances, solar, batteries and observable comfort or performance issues.

Is a NatHERS existing home assessment the same as a new home NatHERS assessment?

No. A new home NatHERS assessment usually assesses a proposed design before construction. A NatHERS existing home assessment assesses a dwelling that already exists and focuses on current performance, documentation gaps and improvement opportunities.

What does the report from a NatHERS existing home assessment show?

The final output may include a Home Energy Rating Certificate and information about the dwelling’s energy performance, comfort and possible upgrade opportunities. The exact reporting format depends on the assessment pathway and scheme requirements.

What should I prepare before a NatHERS existing home assessment?

Useful information includes the property address, available plans, renovation history, insulation details, heating and cooling system information, hot water system details, solar or battery information and any known comfort issues.

Assessment Pathway Review

Ready to understand the right pathway for an existing home?

Send the property details, available plans and the reason for the assessment so the assessment pathway can be reviewed.

Send property details for review

NatHERS Assessment Pathways

NatHERS Existing Homes vs New Home NatHERS Assessments

NatHERS is becoming part of two related but different conversations in Australian housing.

For many years, NatHERS has been most commonly understood as a new-home energy rating pathway. Architects, builders, certifiers and energy assessors use NatHERS software to assess the thermal performance of proposed homes before they are built.

Now, NatHERS for existing homes is expanding this framework into dwellings that have already been built.

The two pathways are connected, but they should not be treated as the same thing. A new home NatHERS assessment usually supports design-stage compliance. A NatHERS existing homes assessment is more focused on real built performance, current dwelling condition and upgrade potential.

What is a new home NatHERS assessment?

A new home NatHERS assessment is an energy rating assessment for a proposed dwelling. It is commonly used for new houses, townhouses, apartments and major residential renovations.

The assessor works from documentation such as architectural drawings, elevations, sections, construction details, glazing schedules, insulation specifications and other design information. The home is modelled in approved NatHERS software to assess how well the proposed design is expected to perform thermally.

The output is generally used to support building approval, planning, certification or construction documentation.

In simple terms, a new home NatHERS assessment asks: how well is this proposed home expected to perform if it is built as designed?

What does new home NatHERS assess?

New home NatHERS focuses heavily on the thermal performance of the building shell.

It considers elements such as:

• orientation
• dwelling layout
• climate zone
• roof, wall and floor construction
• insulation levels
• glazing type
• window size and placement
• shading
• ventilation
• thermal mass
• air movement
• heat gain and heat loss

Under NCC 2022, new homes are also subject to higher energy efficiency expectations, including a stronger connection between thermal performance and Whole of Home energy use. This is where 7 Star Energy Rating requirements become important for new residential design.

What is NatHERS for existing homes?

NatHERS for existing homes is the expansion of the NatHERS framework into homes that have already been built.

Instead of modelling a proposed design from architectural plans alone, an existing homes assessment responds to the real dwelling. It considers the home’s current construction, systems, condition, comfort and upgrade opportunities.

In simple terms, NatHERS Existing Homes asks: how does this actual home perform now, and what could improve it?

What does NatHERS existing homes assess?

An existing homes assessment needs to deal with the realities of a built dwelling.

Depending on the assessment pathway and available information, it may consider:

• construction type and dwelling age
• roof, wall and floor insulation
• window and glazing performance
• orientation and shading
• draughts and air leakage
• heating and cooling systems
• hot water systems
• lighting
• fixed appliances
• solar PV and batteries
• ventilation
• comfort issues
• possible upgrades
• documentation gaps or assumptions

The assessment is not simply a new-home rating copied onto an older dwelling. Existing homes often contain unknowns. Plans may be missing. Renovations may have changed the building over time. Insulation may be incomplete or uncertain. Installed systems may be old, inefficient or poorly matched to the dwelling.

The core difference: proposed design vs real built performance

The most important distinction is this: new home NatHERS assesses a proposed design. NatHERS existing homes assesses an actual dwelling.

This difference affects almost everything else: the documentation, the assumptions, the purpose, the audience, the timing and the way results are used.

A new home assessment is usually completed before construction. It helps answer whether the proposed home can meet energy efficiency requirements before it is approved and built.

An existing home assessment happens after the home exists. It is more concerned with what the building is doing now and how it could be improved.

This is the semantic difference Certified Energy should make very clear: new home NatHERS is a design compliance pathway. NatHERS existing homes is a built performance and upgrade pathway.

How the inputs are different

For new homes, the assessor usually relies on design documentation. The model is based on what is specified to be built.

Common inputs include:

• architectural plans
• elevations and sections
• construction systems
• insulation specifications
• window and glazing schedules
• shading details
• ventilation information
• NCC or BASIX requirements
• project climate zone

For existing homes, the input process is different. The assessor may need to use available drawings, homeowner information, site observations, photos, installed system details, utility context and reasonable assumptions where documentation is incomplete.

How the outputs are different

A new home NatHERS assessment usually supports compliance documentation. Its result may be used by builders, designers, certifiers, developers and approval authorities.

An existing homes assessment is more likely to support understanding, disclosure, upgrade planning or future program requirements.

The output may help a homeowner understand:

• how efficient the home is
• why it feels hot or cold
• where energy demand is coming from
• which upgrades may be useful
• whether the home is suitable for electrification
• what could be improved before sale or lease
• how renovation works might be staged

Both pathways can produce energy performance information, but the decision context is different.

How timing changes the role of the assessment

Timing is one of the clearest differences.

A new home NatHERS assessment is usually carried out during design or documentation. Ideally, it happens early enough to influence design decisions before the project is locked in. This allows the team to adjust glazing, shading, insulation, orientation, construction systems or layout before building approval or construction.

An existing homes assessment happens after the home has been built. It cannot change the original design, but it can help inform upgrade decisions. This may include retrofit planning, insulation improvements, system replacement, draught sealing, solar, electrification or future renovation works.

The earlier a new-home assessment happens, the more design influence it can have. The clearer an existing-home assessment is, the more useful it becomes for staged upgrades.

How compliance differs

New home NatHERS is often connected to compliance.

In many jurisdictions, new residential development must demonstrate that it meets energy efficiency requirements. NatHERS is one of the major pathways used to support this. Recent NCC changes increased the minimum star rating or equivalent for new homes and introduced an annual energy use budget for the entire home, including major fixed appliances, solar and batteries.

Existing homes are currently in a different position. NatHERS for existing homes is part of a developing national pathway, including trials, staged rollout and future disclosure possibilities. It should not be presented as identical to new-home compliance.

Where BASIX fits in NSW

In NSW, BASIX is a critical part of residential development compliance.

BASIX applies to new residential development in NSW and some renovations, and covers water, energy use and thermal performance.

This means a new residential project in NSW may involve BASIX and NatHERS depending on the project type and pathway.

An existing homes rating is different. It is not simply a BASIX certificate for an old house. It is a performance assessment pathway for a dwelling that already exists.

Where 7 Star Energy Ratings fit

The 7 Star Energy Rating shift is mainly connected to new home energy efficiency standards under NCC 2022 and state implementation.

For new homes, 7 Star requirements influence design, modelling and compliance documentation. Design teams may need to improve glazing, shading, insulation, thermal mass, ventilation and overall building fabric performance to reach the required outcome.

For existing homes, the conversation is different. A home energy rating may still use a star-based language to explain performance, but the purpose is not the same as proving a proposed new dwelling meets current new-home code requirements.

Where VURB fits

VURB, or Verification Using a Reference Building, is a separate compliance method used in certain new residential design situations.

It is not the standard comparison point for existing home ratings. However, it may be relevant when discussing the range of pathways available for new residential compliance, especially where a proposed design needs to be assessed against a reference building approach.

For this article, VURB assessment pathways should only be understood in the context of new-home compliance. It should not be framed as an existing homes rating pathway.

Who needs which assessment?

A homeowner with an established dwelling may need an existing homes assessment if they want to understand comfort, running costs, upgrade priorities or future disclosure readiness.

A person building a new home may need a new home NatHERS assessment to support design compliance, approval or certification.

An architect or building designer may need new home NatHERS advice during design development to avoid costly late-stage changes.

A renovator may need both forms of thinking. If the project is a major renovation, there may be compliance requirements connected to the proposed works. But the existing dwelling’s current condition may also need to be understood before deciding what upgrades make sense.

A real estate or property professional may increasingly need to understand existing home ratings as disclosure pathways develop.

Common misunderstandings

One misunderstanding is that NatHERS always means the same thing. It does not. A NatHERS assessment for a proposed new dwelling serves a different role from an assessment of an established home.

Another misunderstanding is that existing home ratings are only about energy bills. Energy bills matter, but they are affected by household behaviour, tariffs and occupancy. A rating can help explain the dwelling’s performance more directly.

A third misunderstanding is that a 7 Star new home and a rated existing home should be compared as if they are part of the same compliance process. They are related through energy performance language, but the policy and project context is different.

A fourth misunderstanding is that BASIX, NatHERS, VURB and existing home ratings are interchangeable. They are not. Each pathway has a different purpose, jurisdictional context and documentation role.

Practical project implications

For new homes, NatHERS should be considered early. If the rating is left too late, the design team may need to make rushed changes to glazing, insulation, shading or construction systems.

For existing homes, the assessment is most useful when it is connected to real decisions. This may include whether to insulate, replace windows, install solar, electrify appliances, improve airtightness, upgrade hot water or stage renovation works.

For NSW projects, the distinction between BASIX, new home NatHERS and existing home ratings should be made clearly. A new dwelling may need BASIX and NatHERS as part of approval. An established home may need an existing homes assessment for advice, disclosure readiness or upgrade planning.

For consultants, the opportunity is to help clients understand the right pathway before the wrong type of assessment is requested.

Assessment Pathway Advice

Need the right NatHERS pathway for your project?

Certified Energy can assist with both new-home NatHERS and emerging existing-home assessment pathways.

Speak with Certified Energy about your assessment pathway

Home Energy Rating

Are Existing Home Energy Ratings Mandatory in Australia?

Existing home energy ratings are becoming a more important part of Australia’s residential energy performance system.

For homeowners, sellers, buyers, landlords, real estate agents and renovation teams, one of the most common questions is whether these ratings are already mandatory.

The short answer is that existing home energy ratings are not yet mandatory across Australia. However, the policy direction is changing. National and state-based frameworks are being developed to support home energy rating disclosure, particularly when homes are sold or leased.

This means homeowners do not need to assume that every existing home must already have a rating. But it also means that energy performance information is likely to become more visible in the property market over time.

Why this question matters

Home energy ratings are no longer only a technical issue for new-build compliance. They are becoming part of a wider conversation about housing quality, energy costs, comfort, electrification, emissions and property disclosure.

For existing homes, this is especially important. Many Australian dwellings were built before current energy efficiency standards and can be expensive to heat or cool. A rating can help make this performance visible.

The policy question is whether this information should remain voluntary or become part of standard property disclosure when a home is sold or leased. That is the area currently being tested and developed as part of Australia’s wider residential performance transition.

Are home energy ratings mandatory for existing homes now?

In most parts of Australia, existing home energy ratings are not yet mandatory for ordinary homeowners.

That means a typical owner of an established home usually does not need to obtain a rating simply because they live in the property. They may choose to obtain one for renovation planning, sale preparation, comfort upgrades, electrification or energy efficiency advice, but it is not yet a blanket national requirement.

The exception to keep in mind is that energy rating disclosure requirements can vary by jurisdiction and property type. Some locations already have established disclosure expectations, and future state or territory schemes may introduce new requirements at different times.

For this reason, the safest wording is not “mandatory in Australia” or “not mandatory anywhere”. The more accurate position is that existing home energy ratings are not yet mandatory across Australia, but disclosure schemes are developing and may apply differently depending on location and transaction type.

What is disclosure at sale or lease?

Disclosure means that a home energy rating is shared publicly or provided to prospective buyers or renters when a property is advertised, sold or leased.

This is different from simply getting an assessment for personal use. A homeowner might choose to have a rating prepared to understand upgrade options. Disclosure is about whether that rating needs to be shown to the market.

A disclosure scheme can help buyers and renters compare homes more clearly. It can also help sellers, landlords and agents explain a home’s comfort, running costs and upgrade potential.

The key policy question is how disclosure should happen fairly, consistently and practically across different housing types, climates, ownership situations and property markets.

What is happening nationally?

Australia has been developing a national approach to home energy rating disclosure. The purpose is to create a framework that states and territories can use when introducing disclosure schemes.

This matters because property, tenancy and building processes are not controlled by one single national rule. State and territory governments play a major role in deciding how and when disclosure requirements are introduced.

A national framework helps create consistency, but it does not automatically mean every existing home in Australia must already disclose a rating. Implementation still depends on government decisions, timing, legislation, programs and market readiness.

What is happening in NSW?

NSW is one of the key jurisdictions testing home energy rating disclosure for existing homes.

The current NSW direction is staged. First, trials are used to test how ratings work in real sale and lease situations. Then a voluntary disclosure rollout is expected. A future mandatory disclosure stage may follow later, but the timing has not yet been confirmed.

This staged approach is important. It means NSW is not simply switching overnight from no disclosure to full mandatory disclosure. The government is testing systems, consumer information, real estate processes and implementation details before a broader requirement is introduced.

For homeowners, this means there may be value in understanding Home Energy Rating pathways early, especially if they are planning to sell, lease, renovate or upgrade an existing home in the coming years.

How does NatHERS for existing homes fit in?

NatHERS has long been associated with new homes, where star ratings are used to assess thermal performance before construction.

NatHERS for existing homes gives Australia a more consistent way to assess and communicate the energy performance of homes that have already been built.

For existing homes, the rating process needs to reflect the real dwelling. It may consider the building fabric, installed systems, comfort, energy use, appliances, solar and upgrade opportunities. This makes it useful not only for disclosure, but also for planning better retrofit decisions.

Is this different from new-home compliance?

Yes. Existing home energy rating disclosure is different from new-home energy compliance.

New homes and major renovations may need energy assessments as part of building approval, planning or construction documentation. In NSW, BASIX for new residential development may apply to new homes and some alterations and additions. NatHERS is also commonly used in new-home energy compliance.

Existing home ratings are different because they assess a dwelling that has already been built. The question is not only whether the home meets a new-build compliance pathway, but how the existing dwelling performs now and what information should be made visible to owners, buyers, renters or the market.

Are sellers or landlords required to disclose a rating?

In most jurisdictions, sellers and landlords are not yet required to disclose an existing home energy rating as a universal rule.

However, this is the area most likely to change. The policy focus is not usually on requiring every homeowner to rate their home at all times. It is more commonly focused on disclosure at key decision points, such as when a home is listed for sale or lease.

This is why real estate agents, landlords and property professionals should pay attention to the staged rollout. Even where disclosure is voluntary first, it may become part of standard property marketing and due diligence over time.

Should homeowners get a rating before it becomes mandatory?

A homeowner may choose to obtain a rating before any future mandatory requirement if they want clearer information about the home’s performance.

This can be useful when planning:

• insulation upgrades
• draught sealing
• window or glazing improvements
• heating and cooling replacement
• hot water upgrades
• solar or battery decisions
• electrification
• renovation works
• sale preparation
• rental property improvements

For some homes, early assessment may help avoid poor sequencing. For example, a homeowner may discover that improving the building fabric should come before investing in larger mechanical systems. In other cases, the rating may help support a staged upgrade plan over several years.

What should project teams do now?

Project teams should avoid treating existing home ratings as a one-size-fits-all compliance requirement. Instead, they should clarify the purpose of the assessment.

The first question is whether the rating is needed for:

• voluntary homeowner advice
• renovation planning
• government program participation
• property disclosure preparation
• portfolio review
• rental property upgrade planning
• future compliance readiness

Once the purpose is clear, the right assessment pathway becomes easier to identify. For architects, builders and energy consultants, this is especially important during renovation planning. A home energy rating for an existing home can provide useful context before design decisions are locked in.

What are the risks of giving the wrong advice?

The main risk is overstatement. Saying that all existing home energy ratings are already mandatory across Australia would be misleading.

The opposite risk is underplaying the transition. Saying that ratings are irrelevant because they are not yet mandatory would also be unhelpful.

The most accurate position sits between those two extremes. Existing home ratings are not yet a universal national requirement, but they are becoming part of Australia’s residential energy performance and disclosure landscape.

Practical implications

For homeowners, existing home ratings can provide clarity before upgrades, renovations or sale preparation.

For sellers, a future disclosure pathway may change how energy performance is presented in property marketing.

For landlords, ratings may become relevant to rental quality, comfort and tenant expectations.

For buyers and renters, disclosure could make it easier to compare homes not only by location and appearance, but by likely comfort and energy performance.

For consultants and project teams, the opportunity is to help clients understand the difference between current voluntary assessment, future disclosure and formal compliance obligations.

Assessment Pathway Advice

Unsure whether a home energy rating applies?

If you are unsure whether a home energy rating applies to your property, project or program, Certified Energy can help clarify the current assessment pathway.

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Home Energy Rating

What Is a Home Energy Rating for Existing Homes?

A home energy rating for existing homes gives homeowners, buyers, property professionals and project teams a clearer understanding of how an established dwelling performs.

Unlike a new-build energy assessment, which is usually completed from architectural plans before construction, an existing home rating looks at the dwelling as it currently stands. It considers the building fabric, thermal comfort, energy use, installed systems and practical opportunities for improvement.

As Australia moves toward clearer energy performance information for established dwellings, home energy ratings are becoming more important for renovation planning, electrification, household running costs and long-term property value.

What does a home energy rating measure?

A home energy rating for an existing dwelling looks at the way a home performs as a built environment, not only as a collection of appliances.

Depending on the assessment pathway, it may consider:

• the home’s construction type
• roof, wall and floor insulation
• window type and glazing performance
• orientation and exposure
• shading
• draughts and air leakage
• heating and cooling systems
• hot water systems
• lighting
• solar PV and battery systems
• ventilation and indoor comfort
• likely energy use and upgrade priorities

The purpose is not simply to produce a number. The value of the rating is that it helps translate building performance into practical decisions. A homeowner may discover, for example, that upgrading ceiling insulation should come before replacing an air conditioner, or that draught sealing may improve comfort before larger renovation works begin.

Why are existing homes different from new homes?

New homes are usually assessed before they are built. The consultant works from drawings, specifications and construction details to model the proposed dwelling against the relevant energy performance pathway.

Existing homes are different because the building is already there. The assessment must respond to the real dwelling: its age, construction quality, previous renovations, system choices and defects. Many Australian homes were built before modern energy efficiency expectations were introduced, which means they can be uncomfortable, costly to run and difficult to improve without clear advice.

This is why existing home ratings need to be practical. They should help homeowners understand the current condition of the house and the most useful sequence of improvements.

How does a home energy rating help homeowners?

A home energy rating can help a homeowner make better decisions before spending money on upgrades.

Without an assessment, energy upgrades can become fragmented. A household may install solar panels, replace appliances, add blinds or upgrade heating, but still live in a home that loses heat in winter or gains too much heat in summer.

A rating helps identify where the underlying performance issues sit. For some homes, the priority may be insulation and draught sealing. For others, it may be inefficient heating and cooling, poor hot water performance, or window exposure. In a renovation context, the rating can also help determine which upgrades should be integrated before walls, ceilings or floors are closed up.

When would you need a home energy rating for an existing home?

A home energy rating may be useful when:

• buying or selling an established home
• planning a renovation or extension
• improving comfort in summer or winter
• reducing household running costs
• planning electrification
• replacing heating, cooling or hot water systems
• reviewing solar and battery options
• preparing a staged retrofit plan
• comparing upgrade options before committing to works

It may also become more relevant as the property market, government programs and household energy disclosure systems continue to develop. For many homeowners, the rating will be less about immediate compliance and more about clarity: understanding what the home is doing, why it feels uncomfortable, and where money should be spent first.

Is a home energy rating the same as NatHERS?

NatHERS has traditionally been associated with new homes and major renovations. It provides star ratings that describe the thermal performance of a home, usually using approved software and detailed modelling inputs.

NatHERS is now being expanded to support ratings for existing homes. This creates a more consistent national language around housing energy performance, allowing existing dwellings to be assessed in a way that better aligns with the rating systems already used for new homes.

For homeowners, the important point is that a NatHERS-aligned existing home rating is not simply a new-home assessment copied onto an old house. Existing homes require a different practical approach because the dwelling has already been built and may contain unknowns, ageing materials, past alterations and real-world performance issues.

How does the Residential Efficiency Scorecard relate?

The Residential Efficiency Scorecard is a government-supported home energy rating and advice program that rates a home’s energy use and comfort and provides tailored upgrade recommendations.

It has helped establish a more practical way for Australian households to understand existing home performance. As the national Home Energy Rating system develops, Scorecard and NatHERS-aligned existing home pathways sit in the same broader movement: giving households clearer, more usable information about the homes they already live in.

Is this the same as BASIX?

No. BASIX is a NSW sustainability pathway used mainly for new residential development and certain alterations and additions. It is connected to planning and approval requirements.

A home energy rating for an existing home is different. It is focused on understanding the current performance of an already-built dwelling and identifying improvement opportunities. It may support renovation planning, household comfort, energy efficiency and upgrade sequencing, but it is not the same as preparing BASIX documentation for a new-build approval pathway.

That distinction matters for homeowners. A person searching for an existing home rating may not need BASIX at all. They may need an assessment that explains the condition and performance of their current home.

What should homeowners prepare before an assessment?

The required information depends on the assessment pathway, but homeowners may be asked to provide or assist with:

• the property address
• approximate year of construction
• renovation history
• building plans, if available
• insulation information, if known
• heating and cooling system details
• hot water system details
• solar PV or battery details
• photos or access to key areas of the home
• information about comfort issues, such as rooms that overheat or stay cold

In many existing homes, not all details are known. That is normal. A good assessment process should work with the information available and identify where assumptions, observations or further checks are needed.

Common misunderstandings about home energy ratings

One common misunderstanding is that a rating is only about energy bills. Bills are part of the picture, but they are affected by household behaviour, tariffs, appliances, occupancy and climate. A rating is more useful when it helps explain the performance of the home itself.

Another misunderstanding is that solar panels automatically solve poor energy performance. Solar can be valuable, but it does not necessarily make a home comfortable. A poorly insulated, draughty or overheated home may still need building fabric improvements.

A third misunderstanding is that every upgrade should be done at once. In many homes, staged improvements are more realistic. The benefit of a rating is that it can help prioritise the sequence.

Practical project implications

For homeowners, a home energy rating can support a more confident upgrade plan.

For architects and designers, it can provide useful context before renovation design begins. Understanding the existing dwelling’s performance can help shape decisions around glazing, insulation, shading, airtightness and services.

For builders, it can clarify which performance upgrades need to be integrated into the works rather than added later. For property professionals, it can help explain comfort and operating-cost considerations that are often invisible during a standard inspection.

For consultants, it creates a bridge between technical building performance and practical household advice.

Existing Home Energy Advice

Planning upgrades for an existing home?

If your project involves an existing home, renovation or staged upgrade plan, Certified Energy can assist with understanding the most suitable Home Energy Rating pathway.

Speak with Certified Energy about Home Energy Rating pathways