Existing Homes
Certified Energy participated in the NatHERS for Existing Homes Trial as part of the wider transition toward consistent home energy ratings for existing Australian homes.
Updated context: This article was originally published in March 2025 to announce Certified Energy’s participation in the NatHERS for Existing Homes Trial. Since then, the existing homes rating space has continued to evolve. For current guidance on existing home ratings, start with our Home Energy Rating service page.
NatHERS has long been associated with rating the thermal performance of new homes. The existing homes trial was important because most Australian housing was built before current energy efficiency expectations, yet existing homes are where many households experience high energy bills, poor comfort and unclear upgrade decisions.
The trial tested how existing homes could be assessed, how data could be collected and how rating information could be presented to homeowners, banks, valuers and assessors. The broader aim was to support a more consistent national pathway for understanding and improving the performance of existing homes.
Certified Energy contributed to the NatHERS for Existing Homes Trial through both the Core Stream and the Scale Stream. These streams tested different ways of assessing existing homes and collecting the information needed to produce a home energy rating.
The Core Stream involved trained assessors carrying out more complete assessment workflows, including in-home data collection. The Scale Stream tested how banks, property valuers and NatHERS assessors could work together to collect and assess home performance information at a broader scale.
For Certified Energy, the trial was a practical opportunity to contribute technical experience to a national transition that is likely to shape how existing homes are rated, compared and improved over time.
Current Service
For current guidance on existing home ratings, comfort, performance and upgrade pathways.
Existing Homes
Learn how NatHERS is expanding from new homes into existing home energy ratings.
Certified Energy team members involved in the trial included Jamie, Walter and Manita, bringing together experience in ESD consulting, accredited building design, residential energy assessment and technical modelling.
Their participation helped Certified Energy stay close to the emerging requirements, assessment workflows and practical challenges involved in rating existing homes. This experience now informs how Certified Energy approaches existing home performance, upgrade advice and home energy rating conversations.
The trial helped test how existing home ratings could work in practice. The current focus is now clearer: helping homeowners, lenders and the property industry understand how existing homes perform and where upgrades may improve comfort, running costs and long-term value.
A home energy rating can help make the performance of an existing home more visible. Instead of relying only on age, appearance or broad upgrade advice, a rating can help identify how the home performs and where improvement opportunities may exist.
For homeowners, this can support more informed decisions about insulation, draught sealing, glazing, heating and cooling systems, hot water, solar and other upgrades. For the broader market, home energy ratings may help create clearer information for buyers, renters, lenders and valuers.
This is why Certified Energy sees existing home ratings as more than a compliance exercise. They are part of a wider shift toward understanding how homes actually perform and how targeted upgrades can improve comfort and reduce energy demand over time.
“Existing home energy ratings can help make home performance more visible. Australia has a large existing housing stock, and many households are trying to understand how their home compares, what upgrades matter and how comfort can be improved.”
“The opportunity is not only lower energy use. It is also better comfort, clearer upgrade decisions and a property market that can increasingly recognise the value of efficient homes.”
For homeowners, the most useful question is no longer only whether an existing home can be rated. It is what the rating can help reveal. A home energy rating can support a clearer conversation about comfort, insulation, draughts, glazing, heating and cooling, solar, appliances and upgrade priorities.
As the existing homes rating market continues to develop, Certified Energy will continue to support homeowners, lenders and project teams who need practical, technically informed guidance on home energy performance.
Certified Energy can advise whether a Home Energy Rating, NatHERS Existing Homes pathway or another residential performance assessment may be relevant for your property.