NatHERS Existing Homes
NatHERS Existing Homes is the expansion of Australia’s Nationwide House Energy Rating Scheme into homes that have already been built.
For many years, NatHERS has been most familiar as a new-home rating system used during design and compliance. The existing homes pathway extends the same national rating language into established dwellings, helping homeowners and property teams understand how a real home performs now.
This matters because an existing home is not a proposed design. It has already been built, occupied, altered and maintained over time. A NatHERS Existing Homes assessment is intended to help make that real performance easier to understand.
Quick Answer
NatHERS Existing Homes is the expansion of the Nationwide House Energy Rating Scheme into existing dwellings. It helps assess the current energy performance, comfort and improvement potential of homes that have already been built.
It is different from a standard new home NatHERS assessment. New home NatHERS is usually used before construction to assess a proposed design. NatHERS Existing Homes looks at a real dwelling as it stands today.
For homeowners, buyers, sellers, landlords, designers and property professionals, the pathway can help translate building performance into clearer information about comfort, energy use and possible upgrades.
Australia already has a long-established rating system for new homes. But most homes in Australia have already been built, and many were constructed before current energy efficiency expectations were introduced.
Existing homes can be difficult for households to understand. A home may look well presented but still perform poorly in summer or winter. It may have high running costs, weak insulation, inefficient systems, poor glazing or comfort problems that are not obvious during a standard property inspection.
NatHERS Existing Homes gives a more consistent way to describe this performance. It helps shift the conversation from guesswork toward a structured assessment of how the home actually performs.
A Home Energy Rating is the broader consumer-facing idea: a way to understand how an existing home performs for energy use, comfort and potential upgrades.
NatHERS Existing Homes is one of the key national pathways supporting this shift. It sits within the NatHERS framework and provides a more consistent language for rating existing dwellings.
For a broader definition, see What Is a Home Energy Rating for Existing Homes?
A NatHERS Existing Homes assessment looks at the dwelling as it exists, not only as it may have been designed. The exact information required depends on the assessment pathway, available documentation and the condition of the home.
The assessment may consider:
The purpose is not only to produce a number. A useful assessment can help a homeowner understand what is influencing performance and where improvements may be most effective.
The core difference is timing and purpose.
New home NatHERS usually assesses a proposed design before construction. It is commonly used for compliance, certification and design-stage decision-making. The assessor works from drawings, specifications and construction details.
NatHERS Existing Homes assesses a dwelling that has already been built. It must respond to real construction, previous renovations, installed systems, missing documentation and the actual condition of the home.
For a detailed comparison, see NatHERS Existing Homes vs New Home NatHERS Assessments.
NatHERS existing Home Energy Rating certificates can only be generated by an accredited existing homes assessor.
This distinction matters because existing homes require specific assessment processes. The assessor may need to deal with incomplete documentation, site data, assumptions, existing systems and real-world construction conditions.
For clients, this means the right pathway should be confirmed before assuming that a standard new-home NatHERS assessment is suitable.
Existing home energy ratings are not yet mandatory across Australia as a universal requirement. However, disclosure pathways are developing, and requirements may vary by jurisdiction, program or transaction type over time.
This is why the wording needs to be careful. NatHERS Existing Homes should be understood as an emerging and expanding assessment pathway, not as a blanket requirement for every existing home today.
For a fuller explanation, see Are Existing Home Energy Ratings Mandatory in Australia?
NatHERS Existing Homes may be useful for homeowners who want to understand how their home performs and what upgrades may be worth considering.
It may also be relevant for buyers, sellers, landlords, rental property owners, renovation teams, real estate professionals and organisations reviewing residential portfolios.
The pathway is especially useful where a client needs to understand an established dwelling rather than a proposed new design.
The required information depends on the home and assessment pathway. As a starting point, it is helpful to prepare the property address, available plans, renovation history, photos and details of major systems.
Useful information may include:
If the documentation is incomplete, the assessment may still be possible. The pathway can be reviewed based on the information that is available.
One common misunderstanding is that NatHERS Existing Homes is simply the same as a new home NatHERS assessment. It is not. The existing homes pathway deals with real dwellings, not only proposed designs.
Another misunderstanding is that the rating only relates to energy bills. Bills can be influenced by behaviour, tariffs and occupancy. The assessment is more useful when it helps describe the dwelling’s performance and possible improvement opportunities.
A third misunderstanding is that every existing home must already have a rating. This is not the current national position. The disclosure landscape is developing, but it should not be overstated.
A fourth misunderstanding is that a rating automatically means one specific upgrade is required. In practice, the value of the assessment is that it can help clarify the home’s performance and support better decision-making.
For homeowners, NatHERS Existing Homes can help turn general concerns about comfort and energy use into clearer performance information.
For renovators and design teams, it can help identify existing performance issues before upgrade decisions are locked in.
For sellers, landlords and property professionals, it may become increasingly relevant as home energy disclosure pathways develop.
For consultants, the key is to separate the existing homes pathway from new-home compliance and guide clients toward the correct assessment type.
NatHERS Existing Homes is the expansion of the Nationwide House Energy Rating Scheme into established dwellings. It helps assess the energy performance, comfort and upgrade potential of homes that have already been built.
No. New home NatHERS usually assesses a proposed residential design before construction for compliance purposes. NatHERS Existing Homes assesses a dwelling that already exists and focuses on current performance and improvement opportunities.
A NatHERS Existing Homes assessment may consider the dwelling’s construction, insulation, glazing, shading, heating and cooling systems, hot water, appliances, solar, batteries, ventilation, comfort and possible upgrade opportunities.
NatHERS existing Home Energy Rating certificates can only be generated by an accredited existing homes assessor.
Existing home energy ratings are not yet mandatory across Australia as a universal requirement. Disclosure pathways are developing, and requirements may vary over time by jurisdiction, program or transaction type.
The expansion helps households better understand the performance of homes that have already been built, including comfort, energy use and potential upgrades.
Existing Home Assessment Pathways
Certified Energy can help clarify whether NatHERS Existing Homes is the right pathway for your property.