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EER's in the ACT: 6⭐ ActHERS vs 10⭐ NatHERS

ACT is the only state in Australia with mandatory disclosure of EER for sale of property.

It is a fantastic scheme, launched in March 1999, to ensure all home owners are able to make informed decisions about the performance of a home when they are looking to purchase.

But what few people realise is that the EER for sale of property is not the same as an EER for building approval (new builds, extensions and renovations) and in fact it is issued from a different, much earlier version of energy efficiency rating software:

Both systems have amazing science behind them and are based on the CSIRO calculation engine (Chenath) with weather data and climate records for 69 different regions in Australia. Accredited software programs undergo rigorous NatHERS accreditation before being approved for use.

Both ratings are based on the thermal performance of the building envelope (ie. construction materials and insulation) of the home and do not take into consideration air leakage, solar panels, heating and cooling systems etc.

So what is a sale of property EER?

For starters - and most obviously - it is only out of 6 stars. The reason for this being that back in 1999 the first few generations of energy efficiency software only rated homes out of 6 stars. It is this software, FirstRate v4.05, that was written into the legislation and has not been updated since.

Other differences include it measures performance in points, it provides basic advice to improve the EER and it has increments of 0.5 stars - so homes can only jump from 4.5 to 5.0 stars - not be listed as 4.8 stars.

The assessors that provide these ratings are registered under the ACT Construction Occupations Licencing Act (COLA) and listed as Class A. They are known as building inspectors and provide 5 different reports to owners wishing to list a home for sale - a building inspection, termite and timber pest inspection, energy rating, compliance and conveyancing report.

And what is a Building Approval EER?

For building approval EERs, a Nationwide Home Energy Rating Scheme (NatHERS) accredited software is required. Currently there are 4 accredited software programs:

- AccuRate Sustainability v2.4.0 (3.21)

- FirstRate5 v5.3.1 (3.21)

- BERS Pro v4.4.0.2 (3.21)

- HERO v1.2-beta(3.21)

This software provides MJ/m2 requirements to heat and cool the rooms based on their function.

This means you can clearly see which rooms need more heating or cooling, and how each room and therefore the overall home performs. This is fantastic to inform design decisions regarding window sizes and see how different floor covering etc influence the overall home. Sadly, most EERs are an after thought for approval and not used in this way.

Below is an example from the reports we provided:

These reports can also be done on existing homes, to assess the impact of upgrading windows, improving insulation etc.

These specialist assessors may or may not provide optimisation advice beyond the required minimum 6 stars. Assessors that provide these ratings are also registered under the ACT Construction Occupations Licencing Act (COLA) and listed as either Class A (can assess renovations for BA) or Class B (can only assess new builds for BA).

In the ACT, the assessor does not need to be NatHERS Accredited (just COLA licenced). So reports they provide may or may not include the NatHERS logo:

I hope this has helped clarify some of the differences, to help you make informed decisions and have a better understanding of how EERs work in the ACT.

Further reading:

Please find hyperlinks above to organisations and accreditation systems mentioned.

ACTPLA Energy rating of residential buildings in the ACT

ACT energy-efficiency ratings are a dog's breakfast (Canberra Time, July 2018):

About me:

I am a registered architect and COLA Class B Energy Assessor here in the ACT. I completed my accreditation back in 2011, via a 91318NSW course in building thermal performance assessment (residential). Since my licencing the rules have changed and new NatHERS assessors are required to complete a Cert IV in home energy efficiency and sustainability - my husband and business partner, Paul, is currently completing this course.

We are passionate about improving the quality of homes in and around the ACT, through both our design work and our EER optimisation services.


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