Residential Energy Performance
A Home Energy Rating helps homeowners and property professionals understand the energy performance of an existing Australian home, including its thermal characteristics, installed household systems and opportunities for improvement.
Explore how the NatHERS for Existing Homes framework assesses residential performance, how rating results can inform property and renovation decisions, and what to consider when arranging an assessment.
Explore Existing Home RatingsIn Brief
A Home Energy Rating provides a structured assessment of the energy performance of an existing Australian home. Introduced through the expansion of NatHERS to existing homes, the national framework assesses the dwelling in its current condition, helping households understand its thermal performance and modelled household energy use.
The assessment considers how the building responds to its local climate, including orientation, construction, insulation, glazing and shading. It also examines major household energy systems, such as heating and cooling, hot water, lighting and relevant appliances, together with onsite solar generation and battery storage where present.
Information is collected through an onsite assessment and used in accredited modelling software to produce a thermal star rating and an overall Home Energy Rating. The resulting certificate and upgrade guidance can help homeowners identify areas for improvement and make more informed decisions about comfort, energy efficiency and future renovations. Ratings represent modelled performance under standardised assumptions rather than a measurement of actual household energy bills.
The home's thermal performance and modelled household energy use, based on its existing construction, installed systems and onsite energy features.
An accredited assessor collects information about the existing dwelling and uses approved assessment tools to model its thermal and household energy performance.
A Home Energy Rating Certificate with performance ratings and tailored upgrade guidance to support more informed decisions about the existing home.
Knowledge Navigation
Explore how Home Energy Ratings work for existing Australian homes, what an assessment considers and how the results can support informed decisions about energy performance, property and future improvements.
Foundation
Performance
Assessment
Application
Boundaries
Further Guidance
Assessment Scope
A Home Energy Rating for an existing home provides two complementary results: a thermal Star Rating for the building itself and an overall Home Energy Rating that also accounts for major household energy systems and onsite energy generation.
Thermal Performance
The thermal assessment estimates how much heating and cooling the home requires to maintain comfortable indoor temperatures under standardised conditions. The result is expressed as a Star Rating from 0 to 10, with higher ratings indicating lower heating and cooling demand.
The assessment considers:
Household Energy Performance
The overall energy assessment combines the home's thermal performance with modelled energy use from major fixed systems and appliances, accounting for onsite solar generation and battery storage where present. The result is expressed as a Home Energy Rating on a scale of 0 to 100+, with scores above 100 possible for homes that generate and export more energy than they use.
The assessment may consider:
Two Linked Measures
A strong thermal rating does not automatically mean every installed system is efficient. Equally, efficient appliances cannot fully overcome a home that requires substantial heating or cooling. The two ratings provide different but connected views of the home's energy performance.
Modelled Performance
The ratings use standardised assumptions to support consistent comparisons between homes. Actual energy consumption and bills may differ due to occupancy, comfort preferences, appliance use, energy tariffs and how the home is operated.
Existing Home Assessment
A Home Energy Rating examines the performance of an existing dwelling using information about its current construction, installed energy systems and observable condition.
Many Australian homes were built before today's residential energy-performance requirements were introduced. Their performance may reflect a combination of original construction, later renovations, ageing materials, replaced appliances and changes that are not fully documented in the available building records.
A Home Energy Rating provides a consistent way to assess a dwelling in its present condition. Rather than relying solely on original plans or specifications, the assessment draws on information collected from the completed home, including site observations, measurements and available documentation. Where building details cannot be directly verified, the assessor follows the applicable assessment methodology and evidence requirements.
This information is used to model the home's thermal performance and household energy use under standardised conditions. The results can help homeowners understand the characteristics influencing performance, identify potential areas for improvement and make more informed decisions when planning future upgrades.
Home Energy Rating and NatHERS
Home Energy Rating provides a recognisable way for Australian households to understand the assessed energy performance of their homes. For existing dwellings, the assessment operates within the expanded Nationwide House Energy Rating Scheme (NatHERS), which establishes the technical methodology, assessor accreditation arrangements and quality assurance requirements. Although existing-home and new-home assessments sit within the broader NatHERS framework, they serve different purposes and follow assessment requirements appropriate to their respective building stages.
Certificate Structure
The certificate brings together two complementary ratings, supporting information about the home's energy performance and guidance on potential improvements.
Home Energy Rating Certificate
An assessment of the existing home's energy performance
Thermal Performance
0–10 stars
How well the building's design and construction maintain comfortable indoor temperatures with reduced heating and cooling demand.
Overall Energy Performance
0–100+
Modelled household energy performance, including thermal demand, major energy systems and onsite solar or battery storage where present.
Supporting Performance Information
Building characteristics, estimated energy use and emissions, appliance performance, comfort indicators and renewable energy information where applicable.
Home-Specific Upgrade Guidance
Suggested improvements relevant to the assessed home, helping households consider opportunities to improve energy efficiency and comfort.
Simplified illustration of the information provided. The official certificate contains additional details and assessment results.
Certificate Interpretation
A Home Energy Rating Certificate provides more than a summary of a dwelling's energy performance. It helps explain how the building and its installed systems contribute to the overall results, and where improvements may be worth considering. Understanding the different sections allows homeowners, buyers and property professionals to interpret the ratings in context rather than relying on a single number.
The thermal Star Rating indicates the home's modelled heating and cooling demand, while the overall Home Energy Rating considers broader household energy performance. Reading both results together helps distinguish the contribution of the building fabric from that of installed energy systems and onsite generation.
Information about insulation, glazing, construction and other building characteristics can help explain the thermal result. These details may highlight areas worth investigating when considering improvements to heating and cooling efficiency or indoor comfort.
The assessment of heating, cooling, hot water and other relevant systems helps show how installed equipment influences the overall rating. Solar generation and battery storage may also affect the result. This information can support decisions about replacing or upgrading equipment alongside improvements to the building itself.
Home-specific upgrade recommendations provide a starting point for considering potential improvements. The most suitable actions will depend on the dwelling's condition, household priorities, available budget and the practical requirements of the proposed work. Recommendations should be considered alongside project-specific advice where needed.
Assessment Boundaries
Both assessments use residential energy modelling, but they examine different stages of a home's life and serve different purposes.
Existing Dwelling
A Home Energy Rating assesses a completed dwelling in its current condition. The model is informed by evidence about the existing construction and the energy systems installed at the property.
Assessment basis
Existing construction, observable conditions, installed systems, property records and acceptable supporting evidence, with applicable assessment procedures used where information is incomplete.
Main purpose
To explain the home's current modelled thermal and household energy performance and support more informed decisions about potential improvements.
Typical timing
After construction is complete, including established homes and dwellings that have undergone renovations or alterations over time.
Proposed Dwelling
A new-home NatHERS assessment models a proposed residential design before construction. It uses drawings, specifications and nominated building elements to predict how the completed dwelling is expected to perform.
Assessment basis
Proposed plans, elevations, construction details, glazing selections, insulation levels and other design specifications, together with relevant energy-system information where required.
Main purpose
To assess the predicted thermal performance of a proposed design, together with applicable Whole of Home energy results, and support the relevant residential energy-efficiency compliance pathway.
Typical timing
During design development and before relevant construction documentation or approval requirements are finalised.
Important Distinction
A Home Energy Rating describes the assessed performance of an existing dwelling. It should not be treated as a substitute for the NatHERS documentation, BASIX documentation, Residential DTS assessment, VURB assessment or other approval evidence required for proposed building work.
Where a renovation, extension or new dwelling requires formal approval, the applicable compliance pathway must be considered separately. An existing-home rating may provide useful background information, but its assessment purpose and evidence requirements remain different. For proposed residential designs, explore the NatHERS Assessment pathway.
Thermal Performance
The thermal assessment examines how the home's form, construction and relationship with its local climate influence the heating and cooling energy required to maintain standardised indoor comfort conditions.
Every existing home responds differently to seasonal heat, cold, sunlight and air movement. Orientation, window placement, construction materials and insulation all influence how internal spaces gain or lose heat and how much heating or cooling may be needed to maintain comfortable temperatures.
NatHERS thermal modelling brings these characteristics together using climate information relevant to the property's location. It estimates the heating and cooling energy required under standardised operating conditions and expresses the result as a thermal Star Rating from 0 to 10.
A higher Star Rating generally indicates that the dwelling requires less modelled heating and cooling energy to maintain the specified indoor conditions. A lower rating may indicate greater heat gain or heat loss through the building envelope, helping identify characteristics worth investigating when planning improvements.
Building Characteristics
The model considers how the home's physical characteristics interact, rather than treating any single material or feature as the sole measure of thermal performance.
The direction rooms and windows face, the arrangement of internal spaces and the home's exposure to seasonal sunlight.
Existing construction systems, materials, insulation and the way different parts of the building envelope influence heat transfer.
Window size, orientation, glass and frame performance and their contribution to solar heat gain and heat loss.
Eaves, awnings, external obstructions and other relevant shading elements that influence solar exposure at different times of the year.
Modelled ventilation characteristics and uncontrolled air leakage that may influence heat gain, heat loss and heating or cooling demand.
Climate data relevant to the property's location, including seasonal temperature patterns and solar conditions used in the assessment.
Reading the Result
The thermal Star Rating describes the building's modelled heating and cooling demand under standardised conditions. The efficiency of installed heating, cooling, hot water and other relevant energy systems is considered within the broader Home Energy Rating. Actual household energy use and comfort may differ from the modelled results.
Household Energy Performance
The broader Home Energy Rating considers the relationship between the building's thermal performance, its installed energy systems and any onsite solar generation or battery storage.
Two homes with similar thermal performance can have different overall energy outcomes. The efficiency and energy source of heating, cooling, hot water and other relevant systems influence the amount and type of energy the home is modelled to use.
The household energy component builds on the thermal assessment by modelling relevant installed equipment using standardised occupancy and operating assumptions. Where rooftop solar or battery storage is present, these features are also considered in accordance with the assessment methodology.
The result provides a consistent way to understand how the building fabric, energy systems and onsite generation contribute to overall performance. A home may have a relatively modest thermal Star Rating but a stronger overall Home Energy Rating because of efficient equipment or solar generation. Reading both ratings together helps identify where improvements may be most useful.
Energy Systems
The assessment considers relevant installed systems and energy features, together with standardised assumptions that allow the modelled performance of different homes to be compared consistently.
The type, efficiency and energy source of the systems used to heat and cool the dwelling.
The installed hot-water system, its efficiency and the energy source used to provide household hot water.
Relevant cooking appliances and other fixed energy-using equipment included within the assessment methodology.
Relevant lighting and other household energy loads, including pool or spa equipment where applicable, assessed using the prescribed methodology.
Existing solar photovoltaic generation and its modelled contribution to meeting household electricity needs and reducing reliance on externally supplied electricity.
Installed battery storage and its modelled contribution to managing onsite solar generation and household electricity use.
Reading the Result
The model uses consistent occupancy and operating assumptions so that homes can be compared on a common basis. Actual energy consumption and costs will vary with household size, comfort preferences, appliance use, electricity and gas tariffs, weather and day-to-day behaviour.
The result can help identify opportunities to improve energy performance, but it is not a complete electrification strategy, appliance specification or detailed solar and battery design. Those decisions may require separate technical advice.
Assessment Process
A Home Energy Rating combines property information, an onsite assessment, modelling using approved software and a formal certificate showing the home's assessed performance.
Step 01
The property, purpose of the assessment and access arrangements are confirmed. Available plans, renovation records, appliance details and other relevant information may be reviewed before the visit.
Step 02
An accredited existing-homes assessor visits the property to record its layout, dimensions, construction characteristics, glazing, shading and relevant installed energy systems, following the applicable evidence requirements.
Step 03
The collected information is assessed using software approved for existing-home ratings. The assessor models the dwelling's thermal and household energy performance in accordance with the applicable NatHERS methodology.
Step 04
Once the assessment is finalised, a Home Energy Rating Certificate is issued showing the thermal Star Rating, overall Home Energy Rating, supporting performance information and home-specific upgrade guidance.
At the Property
Existing homes frequently differ from their original drawings. Renovations, replaced windows, added insulation, extensions and changed energy systems can all affect performance, even where those changes are not fully documented.
The onsite assessment establishes the dwelling's observable characteristics and installed systems at the time of rating. Available records and other acceptable evidence support the assessment, while building details that cannot be directly verified are addressed using the applicable methodology and evidence procedures.
After the Visit
The site visit does not produce a rating on its own. The information collected must be translated into a consistent digital model of the dwelling and assessed using the relevant climate data, technical rules and standard operating assumptions.
This modelling stage allows homes to be assessed on a comparable basis rather than relying only on occupant impressions, historical energy bills or a visual inspection of individual features.
Accredited Assessment
Accredited existing-homes assessors must follow the applicable technical guidance, evidence requirements, quality-assurance processes and professional obligations. The official Home Energy Rating Certificate includes a QR code that can be used to access or verify its digital record.
Existing Building Evidence
Existing homes are not always fully documented. The assessment therefore brings together onsite observations, measurements, property records and acceptable supporting evidence to establish a reliable representation of the dwelling.
A completed dwelling may differ substantially from its original drawings. Extensions may have been added, windows replaced, rooms reconfigured or energy systems upgraded without every change appearing in the available documentation.
During the property visit, the assessor records the home's geometry and orientation together with relevant construction, glazing, shading and installed equipment. Measurements, photographs, product information and property records may contribute to the assessment evidence where they meet the applicable requirements.
The objective is not to assume that every feature matches the original specification. It is to establish a defensible representation of the dwelling in its assessed condition, using verified information and the prescribed assessment procedures where details cannot be confirmed directly.
Property Review
The information collected depends on the property and the applicable methodology, but generally covers the building geometry, envelope and relevant household energy systems.
Floor layout, dimensions, ceiling heights, room use, orientation and the relationship between the home and its site.
Observable roof, wall and floor construction together with acceptable evidence about insulation and other concealed building elements.
Window dimensions, frame and glazing characteristics, orientation, eaves, awnings and relevant external shading obstructions.
The type, location, capacity and available efficiency information for installed heating and cooling systems.
Relevant hot-water, cooking and fixed equipment details required for the household energy assessment.
Relevant rooftop solar system details, including available information about capacity and orientation, together with installed battery storage where applicable.
Concealed Construction
Insulation and construction layers may sit behind finished surfaces or within inaccessible spaces. Where a feature cannot be verified directly, the assessor must follow the applicable evidence and modelling requirements, including any prescribed assumptions, rather than treating an unconfirmed improvement as verified.
Assessment Scope
A Home Energy Rating does not replace a structural inspection, defect report, electrical inspection, pest assessment or detailed building-condition survey. Separate specialist advice may be required where those matters are relevant.
Market Readiness
Certified Energy and Cotality are collaborating to explore and refine practical, scalable and quality-assured delivery models for the voluntary phase of NatHERS for Existing Homes.
The wider purpose of the collaboration is to help ensure that reliable information about the energy performance of existing homes can be delivered efficiently and used with confidence as the Australian market develops. Achieving this at scale requires more than a rating methodology alone. It also requires workable assessment processes, appropriate use of property data, a capable accredited workforce and consistent technical quality assurance.
Cotality contributes property-data infrastructure, workflow experience and connections across the wider property sector. Certified Energy contributes an experienced assessor workforce and technical expertise in NatHERS and existing-home energy assessment.
Certified Energy’s accredited assessors visit participating homes, collect evidence about the dwelling as it currently exists and complete the required assessment and modelling process. The collaboration is testing how this onsite technical work can be supported by more efficient data and operational workflows without weakening the integrity of the rating.
The goal is to help build a delivery model in which existing-home energy ratings can become more accessible and scalable while remaining grounded in accredited assessment of the actual dwelling.
This is a non-exclusive collaboration focused on testing market readiness and delivery models for the voluntary phase. It does not assume or guarantee any particular future policy pathway.
Using the Assessment
A Home Energy Rating can help identify opportunities to improve the dwelling's thermal performance, reduce modelled energy demand and make better use of its installed energy systems.
Existing homes rarely have one isolated performance problem. Discomfort may be influenced by a combination of limited insulation, poorly performing windows, uncontrolled air leakage, solar exposure and inefficient heating or cooling equipment.
The rating helps distinguish the thermal performance of the building from the energy performance of the systems operating within it. This provides a more informed starting point for considering improvements rather than selecting products before the home's broader performance has been understood.
The results and accompanying upgrade guidance can support conversations with designers, builders, tradespeople and energy specialists. They may help households identify improvements worth investigating for comfort, energy efficiency or future renovation planning.
Upgrade Areas
The relevant opportunities depend on the home's assessed condition, local climate and the interaction between its building fabric and energy systems.
Sealing uncontrolled gaps around doors, windows and penetrations may help reduce unwanted heat transfer and local discomfort, while maintaining appropriate ventilation.
Roof, ceiling, wall and floor performance may be reviewed where insulation is limited, inconsistent, damaged or absent, subject to construction suitability.
Window coverings, external shading, glazing improvements or targeted window replacement may be considered in response to specific heat-gain or heat-loss issues.
Older or inefficient equipment may warrant review alongside opportunities to reduce the home's underlying heating and cooling demand.
Replacement cycles can provide opportunities to consider more efficient equipment, suitable energy sources and the home's available electrical capacity.
Rooftop solar and battery storage may improve overall modelled energy performance, but system sizing, financial returns and suitability require separate site-specific analysis.
Upgrade Sequencing
Not every home needs a complete renovation. The following stages illustrate ways to organise improvements, rather than a fixed sequence that every household must follow.
Stage 01
Review seasonal operation, shading, ventilation and other low-cost ways of using the existing home more effectively.
Stage 02
Address practical fabric issues, draughts, shading or selected systems where the assessment indicates a worthwhile opportunity.
Stage 03
Use normal equipment replacement cycles to consider more efficient heating, cooling, hot-water and cooking systems.
Stage 04
Coordinate larger envelope, glazing or services upgrades with planned renovations where access and construction sequencing make them more feasible.
Scope Boundary
Suggested opportunities should be tested against the home's construction, climate, budget, condition and planned use. Structural changes, moisture management, electrical upgrades, heritage considerations and product suitability may require advice from appropriately qualified specialists.
A Home Energy Rating is therefore best understood as an evidence base for further decisions rather than a complete retrofit specification or guarantee of a particular energy-saving outcome.
NSW Program Context
The NSW Home Energy Saver loan program includes a NatHERS assessment and certificate for an existing home among the eligible energy-saving activities.
A Home Energy Rating is optional and is not required for every loan application. For households considering several improvements, an assessment may help clarify the home's thermal performance, broader energy performance and the upgrades worth investigating before making investment decisions.
Loan eligibility, approval and access to an assessment remain subject to the participating finance provider's requirements and approved-supplier arrangements. Households should confirm the applicable program conditions before proceeding.
Read about NatHERS assessments and the NSW Home Energy Saver loan
View the NSW Government's Home Energy Saver loan information
2026 Trial Outcomes
The national NatHERS for Existing Homes trial assessed more than 1,000 dwellings across different climates and property types. Its findings supported broader implementation of the rating framework, with Stage 2 commencing on 1 July 2026.
The trial found that the existing-home rating framework was viable and fit for purpose. It demonstrated that assessments could be delivered in real-world conditions while identifying areas requiring further refinement.
The findings informed improvements to assessment software, training, quality assurance and delivery processes. Stage 2 introduced updated tools, broader assessor accreditation and more tailored certificate guidance.
The trial tested both end-to-end assessments and workflows separating onsite data collection from offsite rating work. This provided practical evidence about integrating assessments into property and lending processes.
Read our summary of the 2026 trial outcomes and what they mean for homeowners, assessors, property professionals and the broader residential energy market.
Read the 2026 NatHERS Existing Homes Trial summary →Rating Applications
A consistent rating can help different people understand the assessed energy performance of an existing dwelling, whether the focus is home improvement, property information, finance or the management of a larger housing portfolio.
Households
Homeowners can use the rating to understand modelled thermal performance, household energy performance and potential improvement areas before deciding whether further investigation is needed.
Property Decisions
Where a rating is made available during sale or lease, prospective occupants can compare assessed energy performance and consider potential comfort, running-cost or upgrade implications.
Finance
Finance providers may accept recognised ratings as supporting information for eligible energy-efficiency lending products or home improvement programs, subject to their individual requirements.
Housing Portfolios
Housing providers and program managers can use consistent assessment results to identify performance patterns and inform further investigation and investment planning across multiple dwellings.
Individual Homes
Without a structured assessment, households may rely on energy bills, occupant experience or individual product advice when trying to understand how a home performs. These sources can be useful, but they do not provide the same standardised assessment of the dwelling.
A Home Energy Rating considers the dwelling's building fabric, relevant energy systems and onsite generation through a recognised modelling methodology. This provides a consistent basis for discussing the home's assessed performance, separate from the household's actual energy bills or individual usage patterns.
The result may help a household communicate performance information to other parties, establish a baseline for future comparison or decide which aspects of the home warrant further investigation.
Portfolio and Program Delivery
Larger rating programs require additional planning so that property data, assessment methods and outputs remain consistent across different dwelling types and locations.
Dwelling types, locations, access requirements and program objectives may be reviewed before assessments are scheduled.
Clear field processes help ensure that equivalent information is recorded across properties and can be used reliably in later modelling.
Assessment evidence, modelling decisions and certificate outputs may require coordinated review across the delivery team, in accordance with applicable quality-assurance requirements.
Aggregated results can help identify recurring performance issues and common dwelling characteristics. Investment priorities may then be considered alongside building condition, costs and program objectives.
Scope Boundary
A standard Home Energy Rating provides a consistent assessment of the dwelling, but a finance product, government program, property transaction or portfolio initiative may impose separate rules about assessor eligibility, evidence, certificate age, reporting format or quality assurance. These requirements should be confirmed for the intended use before the assessment is commissioned.
Disclosure and Industry Development
Home Energy Ratings are part of a wider Australian effort to make the thermal and energy performance of existing homes easier to understand, compare and communicate.
Australian property information has traditionally provided limited visibility into the energy performance of existing homes. Buyers and renters may be able to compare location, size, condition and price without receiving equivalent information about modelled thermal performance, heating and cooling demand or household energy performance.
A recognised Home Energy Rating creates a more consistent way to describe these characteristics. It can provide households and property-market participants with information based on an accredited assessment rather than general sustainability claims or isolated product features.
This common rating language may support voluntary property information, jurisdiction-specific disclosure schemes, finance products, housing programs and broader efforts to improve the performance of Australia's existing housing stock.
Disclosure Framework
Disclosure is intended to make recognised energy-performance information available when households are making significant property decisions.
A common certificate and rating method can help people compare homes using information prepared on a consistent basis.
Buyers and renters may gain greater visibility into modelled thermal performance, energy demand and possible areas for future improvement.
Owners who have improved their homes may have a clearer way to communicate assessed performance to the property market.
Consistent ratings may support finance, valuation, retrofit and portfolio-management pathways as the market develops.
Developing System
Existing-home assessment methods, software, assessor capacity, certificates and possible disclosure applications have been developed and tested progressively rather than introduced as one immediate nationwide requirement.
Assessment Method
A national method supports greater consistency in how existing construction, installed systems and onsite energy features are assessed.
Assessor Capacity
Assessors working under the existing-homes framework must meet the applicable training, competency and accreditation requirements so property evidence and modelling decisions are handled appropriately.
Market Testing
Trials have helped test household participation, onsite assessment, software, certificates and the use of ratings within property transactions. Certified Energy's participation in the NSW Real Estate Agent Trial also highlighted the importance of consumer understanding, practical delivery and a clear pathway from assessment to action. Read what the NSW Real Estate Agent Trial revealed.
Government Adoption
Formal disclosure requirements are determined by the relevant jurisdiction and may include specific timing, exemptions, transaction rules and assessment requirements.
Voluntary Use
A household, housing provider, lender or property professional may choose to obtain or use a rating even where no sale-or-lease disclosure requirement applies. Its suitability should be considered against the intended purpose.
Legal Requirements
A Home Energy Rating should not automatically be treated as satisfying a jurisdiction-specific disclosure obligation. Existing legal schemes, including the ACT EER pathway, may use separate assessment, certificate and practitioner requirements.
Residential Energy Pathways
Home Energy Rating assesses a dwelling that has already been built. Other residential energy pathways may assess proposed designs, specified energy systems or compliance requirements for new construction and alterations.
Existing Dwelling
Assesses the current thermal and household energy performance of a completed home using onsite evidence, installed systems and approved existing-homes modelling methods.
Current condition and existing performance
Proposed Design
Models the thermal performance of a proposed new dwelling using plans, construction details and design specifications. Whole of Home assessment may also form part of the applicable new-home requirements.
Explore NatHERSProposed Energy Systems
Assesses specified energy systems, relevant appliances, solar generation and storage alongside the thermal assessment of a proposed new home, where required by the applicable pathway.
Explore Whole of HomeApproval and Compliance
These are distinct residential compliance and assessment pathways. Their relevance depends on the jurisdiction, building classification and proposed work, rather than the existing home's voluntary energy rating.
BASIX · Residential DTS · VURB
Different Assessment Stages
A proposed home can be adjusted before it is built. Its orientation, glazing, insulation, shading and energy systems can be tested against design documentation and revised as the project develops.
An existing home requires a different evidence base. The assessor establishes what is present at the property, considers available evidence about concealed construction and records the installed systems relevant to its current energy performance.
The modelling tools and energy concepts may be related, but the assessment purpose, timing and documentation should not be treated as interchangeable.
Choosing the Appropriate Pathway
The same property may be discussed in several energy contexts, but each pathway should retain a clear role.
Use Home Energy Rating where the purpose is to understand the energy performance of a dwelling that is already built.
Use new-home NatHERS and the relevant Whole of Home requirements where a dwelling is being designed before construction.
Use the applicable BASIX, NatHERS, DTS, VURB or other jurisdictional pathway for proposed building work requiring formal approval.
Check whether a separate state or territory disclosure scheme applies when a rating is intended for the sale or lease of a property.
Core Boundary
The rating may provide valuable context for renovation planning or future property decisions, but proposed building work must still be assessed against the planning, building and energy requirements applicable to that project.
Jurisdictional Disclosure
Both pathways assess aspects of residential energy performance, but they serve different purposes and should not be treated as interchangeable certificates.
National Assessment
A Home Energy Rating assesses the current thermal and household energy performance of an existing dwelling within the NatHERS for Existing Homes framework.
Assessment scope
Existing building fabric, thermal performance, installed energy systems, onsite generation and storage, as applicable.
Typical use
Household understanding, upgrade planning, voluntary property information and eligible finance or housing programs.
ACT legal status
A standard NatHERS Existing Homes certificate should not be used in place of an ACT EER Statement where the ACT disclosure scheme applies.
ACT Disclosure Document
The ACT Energy Efficiency Rating Disclosure Scheme is a separate legislated pathway for disclosing the energy performance of residential properties covered by ACT sale requirements.
Assessment scope
Energy performance assessed in accordance with the applicable ACT House Energy Rating Scheme requirements.
Practitioner requirements
The assessment and statement must be prepared through the ACT pathway by a practitioner holding the required authorisation.
Certificate requirements
The scheme has its own assessment, documentation and statement requirements, which must be followed for the relevant transaction.
Why the Boundary Matters
Both pathways involve residential energy assessment, but they use different rules and serve different purposes. A recent Home Energy Rating for an ACT property does not automatically establish compliance with the territory's sale disclosure requirements.
The intended use of the document therefore matters. An assessment commissioned to help a household understand or improve its home is not necessarily valid for a regulated property transaction.
Where an EER Statement is required for the sale of an ACT property, the appropriate ACT assessment pathway should be confirmed before work begins. This helps ensure the correct practitioner, methodology and documentation are used.
Three Different Layers
These related concepts operate at different levels and should remain clearly separated.
Assessment
A national method for assessing the current thermal and household energy performance of an existing home.
Policy Framework
A national policy framework that jurisdictions may draw on when developing residential energy disclosure arrangements for sale or lease.
Legislated Scheme
An existing ACT legal pathway with its own requirements for applicable property transactions, practitioners and statements.
Current Boundary
Under the current arrangements, the national Home Energy Rating and the ACT EER disclosure pathway remain separate. Before commissioning an assessment for a property transaction, confirm the requirements applying to that property and the intended use of the resulting document.
Program Transition
The Residential Efficiency Scorecard helped establish a practical approach to assessing existing Australian homes. NatHERS for Existing Homes now provides a broader national framework, with its own assessment methodology, ratings and certificate.
Introduced in 2017, the Residential Efficiency Scorecard provided households with a structured assessment of an existing home. It considered building fabric, major fixed appliances and seasonal comfort, then provided a rating and tailored suggestions for improving performance.
The program also contributed practical experience in onsite data collection, assessor training, household communication and upgrade guidance. This experience helped inform the development of the national existing-homes rating approach.
Scorecard and Home Energy Rating share a broad purpose, but they do not use identical assessment methods, certificates or rating outputs. An earlier Scorecard result should not be presented as a current NatHERS Home Energy Rating.
Understanding the Transition
The underlying purpose is familiar, but the national methodology and certificate structure are different.
Shared Purpose
Both approaches help households understand assessed energy performance and identify possible areas for improvement.
Broader Alignment
Home Energy Rating operates within the expanded NatHERS framework, while retaining assessment requirements specific to completed homes.
Expanded Results
The current certificate distinguishes the thermal star rating from the broader Home Energy Rating covering household energy performance.
Current Certificate
A previous Residential Efficiency Scorecard report cannot be assumed to meet the requirements of a current NatHERS Home Energy Rating Certificate.
Existing Scorecard Reports
A previous Scorecard report may help explain the assessed condition of a home at that time and record earlier upgrade recommendations. Its findings should be considered alongside renovations, equipment changes or deterioration since the original assessment.
Current Evidence
Where a lender, housing program, property process or homeowner requires an assessment of present performance, confirm which certificate and assessment pathway is accepted before relying on an older Scorecard report.
Legacy Guidance
Certified Energy retains separate legacy guidance explaining how the Residential Efficiency Scorecard worked, what its reports contained and how it relates to the current Home Energy Rating pathway.
View Residential Efficiency Scorecard legacy guidance
Built on a National Framework
NatHERS provides Australia's national framework for assessing residential energy performance. Its expanded Existing Homes pathway uses a consistent assessment methodology, approved software and assessor accreditation requirements to support comparable Home Energy Ratings. Certified Energy brings practical assessment experience and independent technical advice to help households and organisations understand the appropriate pathway for their properties.
NatHERS and Home Energy Rating are Australian Government program trade marks. Certified Energy is an independent assessment provider and does not act on behalf of the Australian Government. Assessments and certificates are subject to the applicable assessor accreditation, software and program requirements.
Assessment Preparation
The assessor collects essential property information during the site visit. Clear access and any reliable records already available can make the assessment more efficient and help reduce uncertainty about the home's construction and installed systems.
Existing homes are often assessed without a complete set of drawings or specifications. Original plans may have been lost, renovations may not be fully documented and some construction details may be concealed behind finished surfaces.
These gaps do not automatically prevent an assessment. During the site visit, the assessor can measure the dwelling, record visible building elements and collect information about the energy systems currently installed.
Where supporting documents are available, they may help explain changes to the home and provide evidence for features that are difficult to verify visually. The assessor must determine whether that information meets the applicable evidence requirements. The assessment should reflect the dwelling in its present condition rather than only its original design.
Helpful Preparation
Not every item is required for every home. You do not need to assemble a complete documentation package before discussing an assessment. Available information is reviewed alongside the assessor's onsite observations.
Arrange safe access to internal rooms, relevant external areas and installed heating, cooling, hot-water, solar and battery equipment. Do not enter unsafe spaces or access electrical equipment yourself.
Locate any available drawings, renovation documentation, invoices, installation records or photographs of completed work. These may help establish construction details where acceptable evidence is required.
Have available any accessible model numbers, labels or documentation for relevant heating, cooling, hot-water and fixed energy systems. The assessor can advise if further information is needed.
Identify extensions, added insulation, replaced windows, new appliances and other changes made since the home was built. Supporting records may help verify relevant details.
Missing Information
Where construction details or equipment specifications cannot be observed or supported by acceptable evidence, the assessor follows the applicable assessment rules. Unverified insulation, materials or system specifications should not be assumed to be present simply because they may have been included in the original design.
Frequently Asked Questions
NatHERS for Existing Homes entered Stage 2 on 1 July 2026. The Home Energy Rating Certificate brings together information about the dwelling's assessed thermal performance, household energy performance and potential upgrades. Certificate presentation and program requirements may continue to develop, so the applicable format should be confirmed when commissioning an assessment.
A Home Energy Rating is an accredited assessment of a dwelling that has already been built. It considers the home's current construction, thermal performance, installed energy systems and onsite energy features rather than assessing a proposed design from plans alone. Read the short guide to Home Energy Ratings.
Home Energy Rating is the public-facing term for the assessment and certificate available through NatHERS for Existing Homes. The NatHERS framework provides the technical methodology, approved software, assessor accreditation requirements and quality-assurance arrangements behind the rating.
A new-home NatHERS assessment models a proposed dwelling using architectural plans, construction details and specifications. A Home Energy Rating assesses a completed dwelling using onsite observations, measurements, installed systems and evidence about its current condition. The two pathways have different purposes and documentation requirements. Compare existing-home and new-home assessments.
Yes. A standard NatHERS Existing Homes assessment involves an onsite visit by an appropriately accredited assessor. The assessor records the dwelling's geometry, construction, glazing, shading and relevant installed energy systems, together with available evidence about features that cannot be directly observed.
In many cases, yes. Existing homes can often be measured during the property visit. Plans, renovation records, product information and installation documents may still be useful where they provide acceptable evidence of concealed construction or changes made to the dwelling. Missing information is handled under the applicable assessment rules. Read more about ratings without original plans.
The certificate includes a thermal star rating on a 0–10 scale, reflecting modelled heating and cooling demand, and an overall Home Energy Rating on a 0–100+ scale, which also considers household energy systems, onsite solar generation and battery storage. The certificate provides supporting performance information and upgrade guidance. These results are modelled under standard assumptions rather than measured household energy bills or guaranteed comfort outcomes.
Not necessarily. The rating uses standardised modelling assumptions so different homes can be compared consistently. Actual energy consumption and costs vary with household size, occupancy, comfort preferences, appliance use, energy tariffs, weather and everyday behaviour. The certificate should not be interpreted as a prediction of the household's exact bills.
Yes. The assessment can identify areas of weaker thermal or household energy performance and provide guidance about potential improvements. These may include draught sealing, insulation, glazing, shading, heating and cooling, hot water, appliances, solar or battery storage. The rating does not replace detailed retrofit design, electrical advice, structural assessment or product specification. Learn how upgrade guidance may be included.
A national disclosure framework exists, but it does not make NatHERS Home Energy Ratings mandatory for every property sale or lease in Australia. State and territory requirements depend on the property and transaction. Some jurisdictions have separate disclosure arrangements that should not be confused with a standard NatHERS Existing Homes certificate. Learn more about mandatory rating requirements.
No. The ACT Energy Efficiency Rating Disclosure Scheme is a separate legislated pathway with its own assessment, practitioner and documentation requirements. A standard NatHERS Existing Homes certificate should not be used as a substitute for an ACT EER Statement where the ACT disclosure scheme applies.
No. Home Energy Rating assesses a completed dwelling in its existing condition. Proposed new homes, alterations and additions may require separate new-home NatHERS, BASIX, Residential DTS, VURB or other approval documentation depending on the project and jurisdiction.
No. The Residential Efficiency Scorecard was a separate existing-home assessment program that was wound down in 2026. NatHERS for Existing Homes uses a different methodology, rating structure and certificate. An earlier Scorecard report should not be presented as a current Home Energy Rating Certificate. View the Residential Efficiency Scorecard Legacy Guide.
The timeframe depends on dwelling size and complexity, location, access, available documentation and the evidence requiring review. The complete process includes preparation, an onsite visit, energy modelling, quality checks and certificate production. The site visit and the total time to receive the certificate are not necessarily the same. Read more about assessment timeframes.
Cost depends on factors such as dwelling size, construction complexity, location, travel, access, available evidence and the intended use of the certificate. Portfolio assessments, program delivery and additional reporting may require a separately defined scope. Read more about Home Energy Rating costs.
The certificate records the dwelling in its assessed condition. Its formal validity and acceptance should be checked against the applicable program or transaction requirements. Renovations, glazing or insulation changes, replacement energy systems, solar installation or battery storage may mean an earlier certificate no longer accurately represents the home. A lender, government program or property process may also specify how recent a certificate must be.
Yes. Portfolio and program delivery can involve coordinated property triage, onsite data collection, accredited modelling, quality assurance and structured reporting across multiple dwellings. The delivery approach should be scoped around the properties, required outputs, assessor availability and any program-specific requirements. Read more about Home Energy Ratings for housing portfolios.
The NSW Home Energy Saver program guidelines referenced by Certified Energy include a NatHERS assessment and certificate for an existing home among the eligible activities. The assessment is optional and is not required for every loan application. Current program terms should be checked before making financial commitments.
Access depends on household eligibility, loan approval and any participating finance provider or approved-supplier requirements. Learn how the program pathway works.
Related Knowledge
Explore focused guidance on assessment methods, existing-home evidence, upgrade decisions and the delivery of Home Energy Ratings across individual dwellings and larger housing portfolios.
Foundation
A concise introduction to how existing Australian homes are assessed and what the resulting rating is intended to explain.
Read the short guide
Comparison
Understand the difference between assessing a completed dwelling and modelling a proposed new-home design for compliance.
Compare the pathways
Site Assessment
Explore the building fabric, windows, shading, installed systems and supporting evidence considered during an existing-home assessment.
Explore the site review
Documentation
Learn how site measurements, property records, photographs and other evidence can help when original drawings are incomplete or unavailable.
Review the evidence options
Assessment Delivery
Examine the real-world challenge of collecting reliable information and delivering consistent ratings across varied and occupied homes.
Read about practical delivery
Portfolio Delivery
See how consistent ratings can support property triage, quality assurance and staged performance planning across multiple dwellings.
Explore portfolio applications
Industry Context
Certified Energy completed more than 500 rating assessments across the national NatHERS for Existing Homes CORE and Scale Stream trials. This work involved both end-to-end home assessments and the testing of data-collection workflows designed for delivery at scale.
We also participated in the separate NSW Real Estate Agent Trial and contributed formal industry feedback on assessment delivery, evidence quality, training and future accreditation pathways.
This practical experience informs our approach to individual home assessments, housing portfolios and the quality assurance needed to support consistent ratings across larger programs.
Read our analysis of the NSW Real Estate Agent Trial outcomes →
Existing Home Assessment
A Home Energy Rating can help you understand your dwelling's current thermal performance, household energy performance and potential improvement opportunities before making upgrades or wider property decisions.
Certified Energy can review your assessment requirements and help establish whether a Home Energy Rating is the appropriate pathway. You can submit your project details even if original plans or renovation records are unavailable. Any additional evidence or program-specific requirements can be discussed during the initial review.
Last reviewed: October 2026. This page is maintained by Certified Energy as part of its Residential Performance Knowledge Hub.
