Home Energy Rating Preparation

Can You Get a Home Energy Rating Without Original Plans?

Original plans are helpful for a home energy rating, but many existing homes do not have complete documentation.

This is common in established Australian homes. The original drawings may have been lost, never passed on during sale, changed by later renovations or replaced by incomplete real estate floor plans.

In many cases, a home energy rating enquiry can still begin without original plans. The key is to provide the best available information so the assessment pathway can be reviewed.

Why original plans are helpful

Original plans can make a home energy rating easier because they show the layout, room sizes, orientation, elevations, construction details and sometimes window information.

They can also help identify which parts of the dwelling are original and which parts have been extended or renovated. This matters because different parts of the home may have different construction standards, insulation levels or glazing types.

Plans reduce uncertainty, but they do not remove the need to understand the home as it exists now.

Why many existing homes do not have complete plans

It is very common for established homes to have missing or incomplete records. A house may have changed owners several times, been extended over decades or had renovations completed without the full documentation being kept with the property.

In some cases, the only available plan is a marketing floor plan from a real estate listing. In other cases, there may be council records, renovation drawings or informal sketches, but not the original construction documentation.

This does not automatically stop the enquiry. It simply means the assessment review needs to identify what information is available and what may need to be collected or confirmed.

What can be used instead of original plans?

If original plans are unavailable, other information may still help the assessment pathway review.

Useful alternatives may include:

• real estate floor plans
• renovation or extension drawings
• council records or approval documents
• site measurements
• property photos
• photos of windows, systems and external elevations
• records of insulation or glazing upgrades
• heating, cooling and hot water system information
• solar PV or battery documentation
• homeowner descriptions of renovation history

The assessor does not need every document before an enquiry can start. The first step is usually to understand what information exists and whether the missing information can be addressed through the assessment process.

Site data can help fill documentation gaps

For existing homes, site data collection can help provide information that is missing from drawings. This may include layout, dimensions, windows, shading, system information and visible construction details.

Depending on the pathway, data collection may involve an assessor or trained data collector recording the dwelling as it currently exists. In some NatHERS existing homes trial delivery models, data could be collected in the home and then used by assessors off-site to produce a rating.

For more detail about the assessment process, see How Does a NatHERS Existing Home Assessment Work?

Photos can help before the pathway is confirmed

Photos do not replace the assessment, but they can help Certified Energy understand the property before confirming the likely pathway or quote requirements.

Useful photos may include:

• front, rear and side elevations
• main living areas
• windows and external shading
• roof, ceiling or subfloor access points, where safely visible
• heating and cooling systems
• hot water system
• solar inverter, panels or battery equipment
• rooms with comfort issues
• renovated or extended areas

Photos should only be taken from safe and accessible areas. Do not enter roof spaces, subfloor areas or unsafe locations just to gather information.

What if the home has been renovated?

Renovated homes can be assessed, but the missing documentation question becomes more important. A renovation may have changed the dwelling’s layout, construction, insulation, windows, systems or roof form.

Helpful renovation information may include:

• approximate year of renovation
• which rooms or areas changed
• whether insulation was added
• whether windows or doors were replaced
• whether heating, cooling or hot water systems were changed
• whether solar or batteries were added
• photos taken during renovation, if available
• builder or product documentation, if available

Even partial information can help. The goal is to reduce uncertainty where possible.

What information is still needed?

Even without original plans, the assessor will still need enough information to describe the dwelling and its energy-related features.

Useful starting information includes:

• property address
• dwelling type
• approximate year of construction
• number of storeys
• any available plans or sketches
• property photos
• renovation history
• known insulation information
• heating and cooling system details
• hot water system details
• solar or battery information
• known comfort issues

For a broader preparation checklist, see What Information Do You Need for a Home Energy Rating?

What are the limits of rating without plans?

A missing plan does not automatically prevent a rating, but it can create uncertainty. Some details may be hidden, difficult to verify or only partly known.

This may affect how the assessor records information, what assumptions can be used and whether additional site data or clarification is needed before the rating can be completed.

The right approach depends on the property, the assessment pathway and the quality of the information available.

Can a real estate floor plan help?

A real estate floor plan can be helpful as a starting point, especially if it shows room layout, approximate dimensions and the relationship between rooms.

However, real estate plans are usually not designed for energy assessment. They may not show construction details, glazing type, insulation, shading, roof form or system information.

Treat a real estate plan as useful supporting information, not as a complete replacement for assessment data.

Should you request a quote if you do not have plans?

Yes. If you do not have original plans, you can still request a pathway review or quote. The important thing is to provide the information you do have.

Start with the property address, available photos, any drawings or floor plans, renovation history, system information and the reason for requesting the rating.

Certified Energy can then review whether a rating pathway is suitable and what further information may be needed.

FAQs

Can you get a home energy rating without original plans?

Original plans are helpful, but they are not always essential for a home energy rating. Many existing homes can still be reviewed using available drawings, site data, photos, observations, system information and permitted assumptions under the relevant assessment pathway.

What can be used instead of original plans?

Useful alternatives may include current floor plans, renovation drawings, real estate plans, site measurements, property photos, system details, renovation history, council records and on-site data collection.

Are original plans required for NatHERS Existing Homes?

Plans can support a NatHERS Existing Homes assessment, but existing homes often have incomplete documentation. The assessor needs enough reliable evidence and data to complete the assessment under the relevant pathway and technical requirements.

What if my home has been renovated but I do not have drawings?

If a home has been renovated without available drawings, provide any information you have, such as approximate dates, photos, invoices, product details, council records or descriptions of what changed. The assessor can confirm what else may need to be checked.

Can photos help with a home energy rating?

Yes. Photos can help clarify the dwelling before the assessment pathway is confirmed. Useful photos may include elevations, rooms, windows, shading, heating and cooling systems, hot water, solar equipment and safely visible insulation or access areas.

Should I request a quote if I do not have plans?

Yes. You can usually begin by sending the property address, available photos, any documents you do have and the reason for the rating. The assessment pathway can then be reviewed.

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Home Energy Rating Assessment

What Does a Home Energy Rating Assessor Look For?

A home energy rating assessor looks for the building features and installed systems that influence how an existing home performs.

For an existing home, the assessment is not just a quick visual inspection. It involves collecting structured information about the dwelling, including the building fabric, orientation, windows, insulation, shading, heating and cooling, hot water, solar, batteries and comfort issues.

The aim is to understand how the home performs now, why it may feel uncomfortable or expensive to run, and what information is needed to support a reliable rating or upgrade pathway.

Why the assessor’s review matters

Existing homes are rarely as simple as a clean set of architectural drawings. A home may have been extended, re-roofed, renovated, insulated, fitted with solar or upgraded with new heating and cooling systems over many years.

The assessor’s role is to turn that real-world condition into structured assessment information. This means looking at both the visible parts of the dwelling and the available documentation that can support the rating.

For a broader explanation of the process, see How Does a NatHERS Existing Home Assessment Work?

The assessor looks at layout and orientation

The layout and orientation of a home influence how it receives sun, shade, wind and heat across the day and year. They also affect how rooms are heated, cooled and ventilated.

The assessor may record:

• dwelling type and number of storeys
• room layout and approximate zoning
• orientation of main living spaces
• exposure to sun and shade
• relationship between windows, rooms and outdoor spaces
• whether certain rooms are more exposed than others

This helps explain why some spaces may overheat, stay cold or require more heating and cooling than others.

The assessor looks at the building fabric

The building fabric is the physical shell of the home. It includes the parts of the dwelling that separate inside from outside and influence heat gain, heat loss and comfort.

The assessor may consider:

• roof and ceiling construction
• external wall construction
• floor and subfloor conditions
• construction materials
• thermal mass
• external doors
• visible gaps, draught paths or weak points
• areas affected by additions or renovations

This part of the assessment helps show how much the home relies on mechanical systems to remain comfortable.

The assessor looks for insulation information

Insulation is one of the most important performance factors in many existing homes, but it is not always easy to confirm. Older homes may have no records, partial insulation or insulation added during previous upgrades.

The assessor may look for information about:

• ceiling insulation
• roof insulation
• wall insulation
• floor insulation
• insulation added during renovations
• visible insulation in accessible areas
• insulation product information, where available
• areas where insulation is missing or uncertain

If insulation cannot be safely viewed or documented, the assessor may need to record the uncertainty and apply the relevant assessment pathway rules.

The assessor looks at windows, glazing and shading

Windows can have a large effect on comfort and energy use. They influence solar heat gain, heat loss, daylight, ventilation and how rooms respond to different seasons.

The assessor may review:

• window size and location
• orientation of windows
• glazing type, where identifiable
• frame type
• eaves, awnings and verandahs
• external blinds or shading devices
• nearby buildings, fences or landscape shading
• rooms affected by glare or overheating

This information helps connect the home’s design and exposure to its heating and cooling needs.

The assessor looks at heating and cooling systems

Heating and cooling systems influence how much energy the home uses to remain comfortable. The assessor may need to record the type of systems installed and how they serve the dwelling.

Relevant details may include:

• air conditioning type
• heating system type
• system locations
• zoned or whole-home systems
• approximate system age, if known
• model information or labels
• whether systems are still in use
• rooms that remain uncomfortable despite system use

This does not mean the assessor is only checking appliances. The performance of the building fabric still has a major influence on how hard those systems need to work.

The assessor looks at hot water and major energy systems

Depending on the assessment pathway, the assessor may also collect information about major fixed systems that affect whole-of-home energy performance.

This may include:

• hot water system type
• lighting
• major fixed appliances
• pool or spa equipment, where relevant
• recent electrification upgrades
• system labels or model details
• known issues with system performance

These systems help complete the picture of how the home uses energy beyond heating and cooling alone.

The assessor looks at solar and batteries, where relevant

Solar PV and batteries may influence whole-of-home energy performance, depending on the assessment pathway.

Useful information may include:

• solar PV system size, if known
• inverter details
• battery details, if installed
• installation date, if known
• photos of system labels
• whether the system is currently operating

Solar and batteries can reduce grid energy use, but they do not replace the need to understand the building fabric, comfort and heating and cooling demand.

The assessor asks about comfort issues

Comfort issues can help explain how the home is experienced in daily life. They do not replace assessment data, 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 harsh sun or glare
• rooms that are difficult to heat or cool
• condensation, dampness or moisture concerns
• areas where the home relies heavily on mechanical heating or cooling

This information helps connect the rating to the lived reality of the home, rather than only treating it as a technical exercise.

The assessor identifies what is known and what is uncertain

One of the most important parts of an existing home assessment is identifying the difference between known information and uncertain information.

Some details may be confirmed from plans, labels, receipts, observations or homeowner records. Other details may be unknown, hidden or only partly visible.

This is why original plans are helpful, but not always available. For that specific question, see Can You Get a Home Energy Rating Without Original Plans?

What is the assessor not looking for?

A home energy rating assessment is not the same as a general building inspection, pest inspection, structural engineering review or electrical safety audit.

The assessor is focused on energy performance, comfort, relevant building features and energy-related systems. If structural, safety, moisture or electrical concerns are identified, those may need to be referred to the appropriate specialist.

This distinction helps avoid confusion about what a home energy rating is designed to do.

How to prepare before the assessor reviews the property

You do not need perfect documentation before making an enquiry, but preparation can make the process smoother.

Useful information may include:

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

For a full preparation checklist, see What Information Do You Need for a Home Energy Rating?

FAQs

What does a home energy rating assessor look for?

A home energy rating assessor looks for the physical features and systems that influence energy performance, comfort and upgrade potential. This may include layout, orientation, insulation, windows, shading, heating and cooling, hot water, lighting, appliances, solar, batteries and comfort issues.

Does a home energy rating assessor check insulation?

Yes. Insulation is an important part of many home energy rating assessments. The assessor may review ceiling, roof, wall or floor insulation where this information is visible, documented or able to be assessed under the relevant pathway.

Does a home energy rating assessor check windows?

Yes. Windows, glazing and shading can significantly affect heat gain, heat loss, daylight and comfort. An assessor may review window size, orientation, glazing type, frame type and external shading.

Will the assessor look at heating and cooling systems?

Yes. Heating and cooling systems are usually relevant because they affect energy use and comfort. The assessor may record system type, location, age, efficiency information and how the systems serve the dwelling.

Does the assessor need access to every room?

For an existing home assessment, access to relevant rooms and areas may be needed so the dwelling layout, windows, systems and visible building features can be recorded. Exact access requirements depend on the assessment pathway and property.

Can an assessor complete a rating without original plans?

Original plans are helpful but not always available for existing homes. Depending on the pathway, the assessor may use available documentation, site data, photos, observations and permitted assumptions where information is incomplete.

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Home Energy Rating

Who Can Request a Home Energy Rating?

A home energy rating can be useful for more than one type of person or project.

Homeowners, buyers, sellers, landlords, renters, renovators, property managers, designers and real estate professionals may all want to understand how an existing home performs for energy efficiency, comfort and upgrade potential.

The important distinction is that a rating can be requested by different parties, but a formal assessment usually needs appropriate property access, the right assessment pathway and a qualified assessor where a certificate is required.

Homeowners can request a home energy rating

Homeowners are one of the most natural groups to request a rating. They may want to understand why the home feels hot, cold, draughty or expensive to run.

A rating can help a homeowner understand the current performance of the dwelling and identify which upgrades may be worth considering first. This may include insulation, glazing, shading, heating and cooling, hot water, solar, batteries or staged renovation measures.

For a broader definition, see What Is a Home Energy Rating for Existing Homes?

Buyers may want a rating before purchasing

Buyers may be interested in a home energy rating because comfort and running costs are not always obvious during an inspection.

A home may present well visually but still have poor insulation, weak glazing, inefficient systems or rooms that overheat or stay cold. A rating can help a buyer understand the likely performance of the property before making longer-term decisions.

In practice, a buyer may need permission from the owner or agent before a formal assessment can occur, because property access is usually required.

Sellers may request a rating before listing a property

Sellers may request a home energy rating to better understand how the home performs before it is listed for sale.

This may be useful where the home has been upgraded, renovated, insulated, electrified or fitted with solar and batteries. A rating can help make energy performance easier to explain in a structured way.

It may also become more relevant as home energy rating disclosure pathways continue to develop in Australia. For the current position, see Are Existing Home Energy Ratings Mandatory in Australia?

Landlords and rental property owners can request a rating

Landlords may request a home energy rating to better understand the comfort and performance of a rental property.

This can be helpful when planning upgrades, preparing for future disclosure expectations, improving tenant comfort or reviewing the long-term condition of a property portfolio.

For rental properties, access arrangements may need to be coordinated with the tenant, property manager or managing agent.

Renters may be interested, but access and permission matter

Renters may want to understand a home’s energy performance, especially where the property is uncomfortable, expensive to heat or cool, or difficult to live in during extreme weather.

However, a formal assessment will usually require property access and may involve areas or systems that are controlled by the owner or managing agent.

This means renters may be able to ask about a rating or encourage one, but the practical assessment pathway usually needs owner or agent approval.

Renovators can request a rating before upgrade decisions

Renovators can use a home energy rating to understand the existing dwelling before committing to upgrade decisions.

This can help identify whether the priority is insulation, windows, shading, draught sealing, heating and cooling, hot water, solar, batteries or a broader staged retrofit pathway.

For renovation projects, a rating may also help design teams understand how the existing home performs before proposed changes are locked in.

Designers, builders and project teams may request support

Architects, building designers, builders and project teams may request home energy rating support when working on an existing dwelling.

This is particularly useful where a project needs to understand real built performance before making design or construction decisions. It can also help separate existing-home performance advice from new-home NatHERS compliance.

For that distinction, see NatHERS Existing Homes vs New Home NatHERS Assessments.

Real estate agents and property managers may coordinate a rating

Real estate agents and property managers may become involved in home energy ratings where a seller, landlord, buyer, renter or property owner wants clearer performance information.

They may help coordinate access, provide property information, communicate with owners or tenants, and help explain why a rating is being requested.

As disclosure pathways develop, property professionals may need to become more familiar with how ratings work and when they are useful.

Who can issue the rating or certificate?

It is important to separate who can request a rating from who can issue the formal certificate.

A homeowner, buyer, seller, landlord, renter or project team may be interested in a rating. But for NatHERS Existing Homes, a Home Energy Rating Certificate can only be generated by an accredited existing homes assessor.

This is why it is useful to confirm the pathway early rather than assuming that any general energy review will produce the same outcome.

When should someone request a home energy rating?

A home energy rating is most useful when it supports a real decision.

Common times to request a rating include:

• before planning energy upgrades
• before a renovation or extension
• before replacing heating or cooling systems
• before electrification works
• before installing solar or batteries
• before listing a property for sale or lease
• when reviewing a rental property
• when assessing a residential property portfolio
• when trying to understand comfort problems

The earlier the rating is considered, the easier it may be to avoid rushed or poorly sequenced upgrade decisions.

What information should be prepared before requesting a rating?

A request does not need to begin with perfect documentation. However, it is helpful to prepare the information that is available.

Useful information may include:

• property address
• dwelling type
• available plans or photos
• renovation or extension history
• known insulation details
• heating and cooling system information
• hot water system information
• solar or battery information
• known comfort issues
• reason for requesting the rating

For a full preparation checklist, see What Information Do You Need for a Home Energy Rating?

FAQs

Who can request a home energy rating?

A home energy rating may be requested by homeowners, buyers, sellers, landlords, renters, renovators, real estate professionals, property managers, designers or project teams, depending on the purpose of the assessment and access to the property.

Can a homeowner request a home energy rating?

Yes. Homeowners can request a home energy rating to understand comfort, energy performance, upgrade priorities, renovation planning or future disclosure readiness.

Can a buyer request a home energy rating before purchasing?

A buyer may want energy performance information before purchasing, but the assessment will usually require appropriate property access and permission. The practical pathway depends on the sale process and the cooperation of the owner or agent.

Can a landlord request a home energy rating?

Yes. Landlords and rental property owners may request a home energy rating to understand comfort, running cost factors, upgrade opportunities and possible future disclosure or rental property performance expectations.

Can a renter request a home energy rating?

A renter may be interested in a home energy rating, but a formal assessment will usually require property access and the owner or managing agent’s approval.

Who can issue a NatHERS existing home certificate?

A NatHERS existing Home Energy Rating Certificate can only be generated by an accredited existing homes assessor.

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Home Energy Rating

Does a Home Energy Rating Provide a Star Rating?

A home energy rating may provide a star rating, but the star rating is only one part of the wider performance picture.

For many homeowners, the idea of a star rating is familiar because NatHERS has long used stars to describe the thermal performance of new homes. As NatHERS expands into existing homes, star rating language is also becoming relevant to established dwellings.

The key is to understand what the star rating does, what it does not measure, and how it differs from broader whole-of-home energy performance.

What does the star rating mean?

The NatHERS star rating describes the thermal performance of a home. It helps explain how much heating and cooling the dwelling is likely to need to remain comfortable in its climate.

A higher star rating generally means the home is better at staying comfortable with less energy for heating and cooling. A lower star rating generally means the home may be more expensive or difficult to keep comfortable.

For an existing home, this can be useful because it gives the homeowner a clearer performance signal than simply saying the home feels hot, cold or expensive to run.

What influences the star rating?

The thermal star rating is influenced by the way the home is designed, built and exposed to its climate.

Key factors may include:

• climate zone
• orientation
• dwelling layout
• roof, wall and floor construction
• ceiling, wall and floor insulation
• window size and placement
• glazing type
• external shading
• thermal mass
• air movement and ventilation
• draughts or air leakage
• renovation and extension history

In existing homes, some of these details may be easy to identify. Others may need to be confirmed through plans, site observations, photos, homeowner information or assessment assumptions.

Is the star rating the same as whole-of-home performance?

No. The thermal star rating and whole-of-home performance are related, but they are not the same thing.

The thermal star rating focuses on the building’s heating and cooling needs. It is mainly about how well the dwelling itself manages heat gain, heat loss and thermal comfort.

Whole-of-home performance may also consider major energy systems and generation, such as hot water, heating and cooling systems, lighting, appliances, solar PV and batteries. This gives a broader view of energy use across the home.

Why the star rating is not the whole answer

A star rating is a useful summary, but it does not explain everything on its own.

For example, two homes may have similar thermal ratings but very different hot water systems, appliance loads, solar systems or battery storage. One may have strong building fabric but inefficient systems. Another may have solar panels but still overheat because of poor shading or glazing.

This is why a home energy rating should be interpreted with the wider assessment information, not only the star number.

Is an existing home star rating the same as a new home rating?

The rating language may be similar, but the assessment context is different.

A new home NatHERS assessment usually rates a proposed design before it is built. It is commonly used for compliance and design-stage decision-making.

An existing home rating assesses a dwelling that already exists. It must respond to real construction, previous renovations, installed systems, missing documentation and the current condition of the home.

For a detailed comparison, see NatHERS Existing Homes vs New Home NatHERS Assessments.

Does a 7 Star requirement apply to existing homes?

The 7 Star conversation is mainly connected to new-home energy efficiency standards under the National Construction Code and state implementation.

Existing home ratings are different. They help assess current performance and identify possible upgrades, but they should not be confused with a new-home compliance requirement.

A homeowner may still want to improve the rating of an existing home, but the assessment should be understood as a performance and improvement pathway, not simply a new-build compliance test.

What appears on a Home Energy Rating Certificate?

A Home Energy Rating Certificate may show the home’s assessed energy performance and provide information that can help guide comfort and upgrade decisions.

The exact certificate format can depend on the assessment pathway and rollout stage. In the NatHERS existing homes trial, participating households received a trial certificate that included a star rating out of 10 and a home energy rating out of 100.

For homeowners, the most useful approach is to treat the certificate as a starting point for understanding performance, not as a replacement for practical assessment advice.

Can the rating help identify upgrades?

Yes. A rating can help identify where an existing home may be improved.

Possible upgrade areas may include:

• ceiling, wall or floor insulation
• draught sealing
• window and glazing improvements
• external shading
• heating and cooling replacement
• hot water upgrades
• solar PV and battery systems
• ventilation improvements
• staged renovation measures

The important question is sequencing. A good assessment can help a homeowner understand which measures should be considered first, rather than treating every upgrade as equal.

Does a higher star rating guarantee lower bills?

A higher star rating generally indicates that the home should need less heating and cooling to remain comfortable. This can support lower running costs, especially when compared with a similar home in the same climate and usage pattern.

However, energy bills are also affected by household behaviour, tariffs, occupancy, appliances, pool equipment, work-from-home patterns, thermostat settings and how systems are used.

This is why the rating should be read as performance information, not as a guarantee of a specific bill amount.

What information is needed to produce a rating?

To produce a rating, the assessor needs enough information about the dwelling and its systems. For existing homes, this may include property details, available plans, site data, photos, renovation history, insulation details and system information.

Useful preparation may include:

• property address
• available plans or drawings
• renovation history
• photos of the home
• known insulation details
• window and glazing information
• heating and cooling system details
• hot water system details
• solar or battery information
• known comfort issues

For a practical checklist, see What Information Do You Need for a Home Energy Rating?

How the star rating fits into the existing homes pathway

As NatHERS expands into existing homes, star ratings help bring a familiar performance language into established dwellings.

This can help homeowners, buyers, sellers, landlords and property professionals understand a home’s performance more clearly. It may also support future disclosure conversations as rating pathways continue to develop.

For more context, see What Is NatHERS Existing Homes?

FAQs

Does a home energy rating provide a star rating?

A home energy rating may provide a star rating, depending on the assessment pathway. Under NatHERS, homes can receive a thermal star rating from 0 to 10, where a higher rating generally means the home is more comfortable and cheaper to run.

What does the NatHERS star rating mean?

The NatHERS thermal star rating describes how well the home performs thermally. It reflects how much heating and cooling the home is likely to need to remain comfortable, based on features such as layout, orientation, insulation, windows, shading and climate.

Is the star rating the same as the whole home energy rating?

No. The thermal star rating and whole-of-home energy performance are related but not the same. The star rating focuses on thermal performance, while whole-of-home performance may also consider appliances, hot water, solar, batteries and other energy uses.

Does a higher star rating mean lower energy bills?

A higher star rating generally indicates a home should need less heating and cooling to remain comfortable. However, actual energy bills also depend on household behaviour, tariffs, occupancy, appliances and system use.

Can an existing home improve its star rating?

An existing home may be able to improve its rating through upgrades such as insulation, draught sealing, window improvements, shading, efficient heating and cooling, hot water upgrades, solar or batteries. The best sequence depends on the home.

Is a 7 Star rating required for existing homes?

7 Star requirements are mainly connected to new-home energy efficiency standards under the National Construction Code. Existing home ratings help assess current performance and upgrade potential, but they should not be confused with new-home compliance requirements.

Rating Pathway Advice

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Home Energy Rating

What Does a Home Energy Rating Actually Measure?

A home energy rating measures how a dwelling performs as a home, not just how much energy appears on a bill.

For existing homes, the assessment may look at the building fabric, thermal comfort, windows, insulation, heating and cooling, hot water, solar, batteries and potential upgrade opportunities.

The purpose is to help homeowners, buyers, sellers, landlords and project teams understand how an established dwelling performs now, and what may improve its comfort and energy efficiency over time.

It measures the home as a whole system

A home energy rating is most useful when it looks at the home as a connected system. The walls, roof, floor, windows, shading and installed systems all affect comfort and energy demand.

For example, an efficient air conditioner may still struggle in a home with poor insulation, large unshaded windows or major draughts. Solar panels may reduce grid electricity use, but they do not necessarily solve overheating, winter heat loss or poor thermal comfort.

This is why a home energy rating for existing homes needs to consider both the building and the systems that support it.

It measures the building fabric

The building fabric is the physical shell of the home. It includes the elements that separate inside from outside and influence how quickly heat enters or leaves the dwelling.

This may include:

• roof and ceiling construction
• external walls
• floors and subfloor conditions
• insulation levels
• windows and glazing
• external doors
• thermal mass
• construction materials
• areas affected by draughts or gaps

Building fabric matters because it often determines how much heating or cooling the home needs before any appliance is even switched on.

It measures insulation where information is available

Insulation is one of the main factors that can influence a home’s heating and cooling needs. A home with poor or missing insulation may lose heat quickly in winter and gain heat quickly in summer.

The assessment may consider insulation in:

• ceilings
• roofs
• walls
• floors
• extensions or renovated areas
• areas where insulation may be missing, damaged or uncertain

In existing homes, insulation is not always easy to verify. The assessor may need to work with available plans, photos, site observations, renovation records and permitted assumptions.

It measures windows, glazing and shading

Windows can have a major effect on comfort and energy use. They influence heat gain, heat loss, daylight, ventilation and exposure to sun.

A home energy rating may consider:

• window size and location
• orientation
• glazing type
• window frame type
• external shading
• eaves, awnings and verandahs
• nearby obstructions
• rooms affected by glare or overheating

This is especially important in Australian homes where summer heat gain, winter heat loss and sun exposure can vary significantly by climate and orientation.

It measures heating and cooling needs

Thermal performance is one of the clearest parts of a home energy rating. It helps explain how much heating or cooling a home is likely to need to remain comfortable.

This is influenced by the design and construction of the home, not only by the appliances installed. A well-insulated, well-shaded home may need less active heating and cooling. A poorly sealed or poorly insulated home may need more energy to remain comfortable.

For existing homes, this can help explain why some rooms are difficult to heat, why certain spaces overheat, or why energy use remains high even after appliance upgrades.

It may measure hot water and major fixed appliances

Depending on the rating pathway, a home energy rating may also consider major fixed systems that contribute to household energy use.

These may include:

• hot water systems
• heating systems
• cooling systems
• lighting
• pool or spa equipment, where relevant
• major fixed appliances
• on-site solar PV
• battery storage

This is where the assessment starts to move beyond the shell of the building and into whole-of-home energy performance.

It may measure solar and batteries

Solar PV and batteries can influence how much energy a home draws from the grid. Depending on the assessment pathway, they may be included as part of whole-of-home performance.

This does not mean that solar alone makes a home comfortable or efficient. A home with solar panels can still have poor insulation, overheating, draughts or high heating and cooling demand.

The rating is most useful when solar and batteries are considered alongside the building fabric and installed systems.

It helps explain comfort issues

Many homeowners first become interested in a home energy rating because the home feels uncomfortable. Some rooms may overheat. Others may stay cold. Some areas may be draughty, damp or difficult to condition.

Useful comfort information may include:

• rooms that are too hot in summer
• rooms that are too cold in winter
• areas with noticeable draughts
• rooms affected by harsh sun or glare
• rooms that are difficult to heat or cool
• moisture or condensation concerns
• areas where the home relies heavily on mechanical heating or cooling

This context helps connect the rating to the lived experience of the home.

It can help identify upgrade potential

One of the practical benefits of a home energy rating is that it can help identify where improvements may be most useful.

Possible upgrade areas may include:

• ceiling, wall or floor insulation
• draught sealing
• window and glazing improvements
• external shading
• heating and cooling replacement
• hot water system upgrades
• solar PV and batteries
• ventilation improvements
• staged renovation measures

The value is not just the list of possible upgrades. It is the sequencing. A rating can help homeowners understand whether the first step should be improving the building fabric, replacing systems, reviewing solar or planning upgrades as part of a renovation.

It is not just a review of energy bills

Energy bills can be useful context, but they do not tell the full story of the home. Bills are affected by household size, behaviour, tariffs, climate, appliance use and whether people work from home.

Two homes with similar bills may perform very differently. One may be efficient but heavily occupied. Another may be inefficient but used lightly. A home energy rating is intended to give a more structured understanding of the dwelling itself.

This is why the assessment focuses on physical features, systems and likely performance rather than treating a bill as the rating.

The exact measurement depends on the pathway

Different home energy rating pathways may have different inputs, certificate formats, software requirements and reporting outputs.

NatHERS Existing Homes, Residential Efficiency Scorecard and other home energy assessment approaches may not all present information in exactly the same way. The important point is to confirm which pathway applies before assuming what will be measured or reported.

For the NatHERS pathway, see What Is NatHERS Existing Homes?

What information helps the assessment?

Because a home energy rating measures the dwelling and its systems, the assessment is easier when useful information is available.

Helpful information may include:

• property address
• available floor plans or drawings
• renovation history
• photos of the home
• insulation information, if known
• heating and cooling system details
• hot water system details
• solar or battery information
• known comfort issues

For a practical preparation checklist, see What Information Do You Need for a Home Energy Rating?

FAQs

What does a home energy rating measure?

A home energy rating measures how a dwelling performs for energy efficiency, comfort and likely energy use. For existing homes, it may consider the building fabric, insulation, windows, shading, heating and cooling, hot water, appliances, solar, batteries and upgrade potential.

Does a home energy rating measure insulation?

Yes. Insulation is one of the key elements that can influence a home energy rating. The assessment may consider ceiling, roof, wall and floor insulation where this information is available, observable or able to be assessed under the relevant pathway.

Does a home energy rating measure heating and cooling?

Yes. A home energy rating may consider heating and cooling needs, installed systems and how the dwelling manages heat gain and heat loss. This helps explain comfort and likely energy demand.

Does a home energy rating include solar panels and batteries?

Depending on the rating pathway, solar PV and batteries may be considered as part of whole-of-home energy performance. These systems can influence how much energy the home uses from the grid.

Does a home energy rating measure energy bills?

A home energy rating is not the same as an energy bill review. Bills are affected by tariffs, occupancy and behaviour. The rating focuses more directly on the dwelling, its systems and its likely performance.

Can a home energy rating identify upgrade opportunities?

Yes. A home energy rating can help identify possible upgrade opportunities, such as insulation improvements, glazing changes, draught sealing, more efficient systems, solar, batteries or staged renovation measures.

Assessment Preparation

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NatHERS Existing Homes

What Is NatHERS Existing Homes?

NatHERS Existing Homes is the expansion of Australia’s Nationwide House Energy Rating Scheme into homes that have already been built.

For many years, NatHERS has been most familiar as a new-home rating system used during design and compliance. The existing homes pathway extends the same national rating language into established dwellings, helping homeowners and property teams understand how a real home performs now.

This matters because an existing home is not a proposed design. It has already been built, occupied, altered and maintained over time. A NatHERS Existing Homes assessment is intended to help make that real performance easier to understand.

Why was NatHERS expanded to existing homes?

Australia already has a long-established rating system for new homes. But most homes in Australia have already been built, and many were constructed before current energy efficiency expectations were introduced.

Existing homes can be difficult for households to understand. A home may look well presented but still perform poorly in summer or winter. It may have high running costs, weak insulation, inefficient systems, poor glazing or comfort problems that are not obvious during a standard property inspection.

NatHERS Existing Homes gives a more consistent way to describe this performance. It helps shift the conversation from guesswork toward a structured assessment of how the home actually performs.

How does this relate to a Home Energy Rating?

A Home Energy Rating is the broader consumer-facing idea: a way to understand how an existing home performs for energy use, comfort and potential upgrades.

NatHERS Existing Homes is one of the key national pathways supporting this shift. It sits within the NatHERS framework and provides a more consistent language for rating existing dwellings.

For a broader definition, see What Is a Home Energy Rating for Existing Homes?

What does NatHERS Existing Homes assess?

A NatHERS Existing Homes assessment looks at the dwelling as it exists, not only as it may have been designed. The exact information required depends on the assessment pathway, available documentation and the condition of the home.

The assessment may consider:

• dwelling layout and construction type
• orientation and climate context
• roof, wall and floor insulation
• windows, glazing and shading
• heating and cooling systems
• hot water systems
• lighting and major fixed appliances
• solar PV and batteries
• ventilation and draughts
• comfort issues and upgrade opportunities

The purpose is not only to produce a number. A useful assessment can help a homeowner understand what is influencing performance and where improvements may be most effective.

How is it different from new home NatHERS?

The core difference is timing and purpose.

New home NatHERS usually assesses a proposed design before construction. It is commonly used for compliance, certification and design-stage decision-making. The assessor works from drawings, specifications and construction details.

NatHERS Existing Homes assesses a dwelling that has already been built. It must respond to real construction, previous renovations, installed systems, missing documentation and the actual condition of the home.

For a detailed comparison, see NatHERS Existing Homes vs New Home NatHERS Assessments.

Who can provide a NatHERS Existing Homes certificate?

NatHERS existing Home Energy Rating certificates can only be generated by an accredited existing homes assessor.

This distinction matters because existing homes require specific assessment processes. The assessor may need to deal with incomplete documentation, site data, assumptions, existing systems and real-world construction conditions.

For clients, this means the right pathway should be confirmed before assuming that a standard new-home NatHERS assessment is suitable.

Is NatHERS Existing Homes mandatory?

Existing home energy ratings are not yet mandatory across Australia as a universal requirement. However, disclosure pathways are developing, and requirements may vary by jurisdiction, program or transaction type over time.

This is why the wording needs to be careful. NatHERS Existing Homes should be understood as an emerging and expanding assessment pathway, not as a blanket requirement for every existing home today.

For a fuller explanation, see Are Existing Home Energy Ratings Mandatory in Australia?

Who is NatHERS Existing Homes for?

NatHERS Existing Homes may be useful for homeowners who want to understand how their home performs and what upgrades may be worth considering.

It may also be relevant for buyers, sellers, landlords, rental property owners, renovation teams, real estate professionals and organisations reviewing residential portfolios.

The pathway is especially useful where a client needs to understand an established dwelling rather than a proposed new design.

What information is usually needed?

The required information depends on the home and assessment pathway. As a starting point, it is helpful to prepare the property address, available plans, renovation history, photos and details of major systems.

Useful information may include:

• property address and dwelling type
• available floor plans or drawings
• renovation or extension history
• known insulation information
• window and glazing details, if known
• heating and cooling system details
• hot water system details
• solar PV or battery information
• known comfort issues

If the documentation is incomplete, the assessment may still be possible. The pathway can be reviewed based on the information that is available.

Common misunderstandings

One common misunderstanding is that NatHERS Existing Homes is simply the same as a new home NatHERS assessment. It is not. The existing homes pathway deals with real dwellings, not only proposed designs.

Another misunderstanding is that the rating only relates to energy bills. Bills can be influenced by behaviour, tariffs and occupancy. The assessment is more useful when it helps describe the dwelling’s performance and possible improvement opportunities.

A third misunderstanding is that every existing home must already have a rating. This is not the current national position. The disclosure landscape is developing, but it should not be overstated.

A fourth misunderstanding is that a rating automatically means one specific upgrade is required. In practice, the value of the assessment is that it can help clarify the home’s performance and support better decision-making.

Practical implications

For homeowners, NatHERS Existing Homes can help turn general concerns about comfort and energy use into clearer performance information.

For renovators and design teams, it can help identify existing performance issues before upgrade decisions are locked in.

For sellers, landlords and property professionals, it may become increasingly relevant as home energy disclosure pathways develop.

For consultants, the key is to separate the existing homes pathway from new-home compliance and guide clients toward the correct assessment type.

FAQs

What is NatHERS Existing Homes?

NatHERS Existing Homes is the expansion of the Nationwide House Energy Rating Scheme into established dwellings. It helps assess the energy performance, comfort and upgrade potential of homes that have already been built.

Is NatHERS Existing Homes the same as new home NatHERS?

No. New home NatHERS usually assesses a proposed residential design before construction for compliance purposes. NatHERS Existing Homes assesses a dwelling that already exists and focuses on current performance and improvement opportunities.

What does NatHERS Existing Homes assess?

A NatHERS Existing Homes assessment may consider the dwelling’s construction, insulation, glazing, shading, heating and cooling systems, hot water, appliances, solar, batteries, ventilation, comfort and possible upgrade opportunities.

Who can provide a NatHERS Existing Homes certificate?

NatHERS existing Home Energy Rating certificates can only be generated by an accredited existing homes assessor.

Is NatHERS Existing Homes mandatory?

Existing home energy ratings are not yet mandatory across Australia as a universal requirement. Disclosure pathways are developing, and requirements may vary over time by jurisdiction, program or transaction type.

Why is NatHERS being expanded to existing homes?

The expansion helps households better understand the performance of homes that have already been built, including comfort, energy use and potential upgrades.

Existing Home Assessment Pathways

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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

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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.

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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

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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.

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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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