NatHERS Existing Homes assessment pathway explained

The NatHERS Existing Homes assessment pathway is a framework under the Nationwide House Energy Rating Scheme designed to provide energy ratings for existing residential buildings a separate stream from the established new homes pathway. It allows accredited assessors to assess existing dwellings for energy performance, supporting disclosure schemes, renovation decisions, and government rebate programs. The pathway has staged rollout with distinct accreditation, training, software, and data collection requirements separate from the New Homes stream.

Why Existing Homes is a separate pathway

The original NatHERS framework was designed for new dwellings buildings where the design documentation is available, materials and construction systems are known, and the assessment can be modelled with confidence. Existing homes are different. Construction details are often not documented, materials are inferred rather than specified, and the assessor must work from on-site observation and measurement.

Building a separate pathway recognises that the assessment task is genuinely different. New Homes assessment is largely a desk exercise with documentation. Existing Homes assessment requires site visits, measurement, inspection, and data collection a different skill profile and a different methodology.

How it differs from the New Homes pathway

New Homes assessment takes design documentation and produces a star rating based on modelled energy performance. The assessor works from drawings, specifications, and product data.

Existing Homes assessment takes the building as it actually is. The assessor visits the property, measures dimensions, identifies materials and construction systems through inspection, and produces a rating that reflects the as-built condition including the imperfections, additions, and substitutions that accumulate over a building’s lifecycle.

The result is a different kind of rating. New Homes ratings are predictive. Existing Homes ratings are descriptive of the building as it currently exists.

Accreditation requirements for assessors

Existing Homes accreditation is separate from New Homes accreditation. An assessor accredited under the New Homes pathway does not automatically have Existing Homes accreditation. The pathway includes specific training requirements covering site survey methodology, data collection protocols, and the Existing Homes assessment tool.

Accreditation is administered through the same Assessor Accrediting Organisations as the New Homes stream BDAA, ABSA, and DMN. Each AAO will integrate Existing Homes accreditation into its framework as the pathway rolls out.

Tool and software differences

Existing Homes assessment uses a tool designed for the workflow site-based data collection, capacity to work with incomplete or inferred data, and outputs aligned with the Existing Homes rating framework. This is distinct from the AccuRate Sustainability, FirstRate5, and BERS Pro tools used for New Homes.

Practitioners considering the Existing Homes pathway should confirm tool requirements with their AAO. The tool, training, and assessment methodology are all part of the accreditation package.

Data collection methodology

Existing Homes data collection follows a defined protocol. The assessor visits the property, conducts a survey of dimensions and construction, identifies materials through observation, photographs the property, and records the data in the format required by the assessment tool.

Where construction details cannot be observed directly wall cavity content, sub-floor insulation, ceiling insulation the protocol provides default assumptions or inspection methods. The integrity of the rating depends on the assessor following the protocol consistently.

Data collection is more time-intensive than New Homes assessment. The site visit, measurement, and documentation phases are significant. Practitioners adding Existing Homes to their service offering should factor this into pricing and scheduling.

Disclosure schemes and policy direction

The Existing Homes pathway has been developed against the backdrop of energy disclosure policy direction at federal and state level. Mandatory disclosure of energy ratings at the point of sale or lease has been considered in various jurisdictions, and the Existing Homes assessment is the technical instrument that would support such schemes.

Disclosure policy is not uniform across Australia and remains in development. Practitioners should follow the policy direction in their state through the relevant authority and treat published policy directions as guidance to plan against, not as confirmed mandatory requirements until they are legislated.

Commercial opportunity for assessors

The Existing Homes pathway represents a meaningful expansion of the assessable market. New Homes assessment is limited to new construction. Existing Homes assessment opens up the entire existing residential building stock millions of dwellings across Australia.

Drivers of demand include disclosure schemes, government rebate and incentive programs tied to energy ratings, renovation decisions where energy performance is a consideration, and lender and insurer interest in energy performance data.

For accredited assessors, this is an expansion of practice rather than a replacement. New Homes work continues. Existing Homes work is additional.

Practice readiness considerations

Adding Existing Homes to a practice involves accreditation, training, tool licensing, and process design. Site visit scheduling, data collection workflows, report production, and client communication all need to be set up. The first assessments take longer than later ones practice efficiency builds through repetition.

Pricing should reflect the time involved in site-based assessment, not just the desk modelling component. Practitioners pricing Existing Homes work the same way they price New Homes work will find the margin compressed.

Common questions

Existing Homes ratings are not automatically valid for compliance purposes. Their use depends on the policy or program the rating is being used for. A rating produced for a vendor disclosure scheme is not necessarily equivalent to a rating produced for a renovation compliance assessment.

Existing Homes assessment is not a replacement for New Homes assessment. The two pathways serve different purposes and produce different outputs.

Quick reference

Existing Homes equals the separate NatHERS assessment pathway for existing residential buildings. Distinct accreditation, training, software, and data collection methodology. Administered through BDAA, ABSA, and DMN. Supports disclosure schemes, rebate programs, and renovation decisions. Opens substantial new market for accredited assessors.

About CPD On Demand

CPD On Demand produces accredited courses on the NatHERS Existing Homes pathway covering methodology, data collection, tool operation, and practice positioning. Courses are designed to support assessors moving into the Existing Homes stream and to satisfy CPD requirements under the major AAO frameworks.