Homeowners will soon be able to prove their solar panels and energy efficiency upgrade provide greater comfort, thanks to an improved national rating scheme.


The Nationwide House Energy Rating Scheme (NatHERS) will soon release its widely anticipated upgrade that incorporates Victoria’s statewide energy scorecard. The result will be more accurate ratings for existing homes.

Currently, NatHERS generally rates new homes, using CSRIO software that can model a house’s thermal  efficiency based on construction plans to ensure each structure meets the minimum efficiency standards.

(BASIX, used in NSW, assesses “the energy and water use and thermal comfort of your residential development”.)

While this is all well and good, Australia is home to plenty of existing houses that could use an energy efficient retrofit of their own.

The Victorian Residential Efficiency Scorecard program uses a 10-star rating system, the same as NatHERS, to measure existing homes based on the building’s structure, fixed appliances and any additional features such as solar panels that may have been installed after initial construction.

Independent assessors rate a home’s efficiency based on everything from windows and insulation to heating and cooling systems, inputting the data into a government supported webtool to reach an overall score.

In addition to efficiency ratings, the Victorian Scorecard includes a hot weather rating to measure how comfortable a house is without a cooling system, a feature that will come in handy as temperatures rise.

These ratings are extremely helpful for homeowners, offering advice and options to upgrade equipment or renovate a home to be more energy efficient.

This is a key component missing from NatHERS, which provides no advice to homeowners on how to upgrade their homes, operating on the assumption that few options exist to significantly upgrade buildings after construction.

NatHERS has been testing a pilot scorecard program since 2018 and 2019, measuring houses in all capital cities to accommodate different types of housing, climate variations and an accreditation process suitable for assessors in different states.

Based on the pilot, NatHERS stakeholders agreed that now is the time to roll out ratings to existing homes while continuing to test and tweak the Scorecard as needed.

The program is expected to hit the open market quickly so that a wide variety of energy rating tools for existing homes can apply for accreditation, ensuring the earliest possible delivery for ratings.

Rating home efficiency, both new and existing, is already playing an increasingly important role in driving a more sustainable housing market.

One study in the ACT, the only territory that mandates energy efficiency disclosure, found that homes that scored high in energy efficiency fetched higher prices, with a 2.4 per cent increase for 6 stars and a 9.4 per cent jump for 7 star homes.

By measuring existing homes, homeowners can make renovations to raise property values when selling and aspiring buyers can better judge sustainable housing options.

Join the Conversation

7 Comments

Your email address will not be published. Required fields are marked *

  1. David, in fact NatHERS software is actually attempting to show energy efficiency by estimating the potential energy consumption, through heating & cooling loads, based the assumed occupants habits/behaviours and as such by increasing/improving the thermal shell and delivering what it hopes is an energy efficient house. However the word assumed habits/behaviours is where the issue lies. Energy efficient homes will only ever become a factor once a value is put on it through mandatory disclosure, then you might see a change in consumer behaviour. In my opinion anyway.

  2. Well first is it 6 Stars NatHERS or 6 Stars Scorecard? Not that it matters that much as both are based on pretty thorough scientific data and average behaviours. So the key thing is that no system, except for possibly the NABERS residential performance rating, will ‘rate’ by how much energy you actually use because is so highly variable.

    Its worth noting that you can put a 1 star person in a 10 star house and it could perform badly due to how they use it. Similarly you can put a 10 star person into a 1 star house and they can make it perform reasonably well. So much depends on the way its used.

  3. re:”NatHERS generally rates new homes,using CSRIO software that can model a house’s energy efficiency” -the software measures thermal efficiency, not actual home energy efficiency.

    1. thanks David… this is what happens when you ignore the little warning bell in your head!

      fixing now