Software updates in 2022
The Australian Building Codes Board (ABCB) has updated the energy efficiency provisions in the National Construction Code (NCC) 2022. Changes will be adopted from 1 October 2022, with a 12 month transition period.
The climate files in accredited software tools have been updated with more recent and more accurate weather data. To minimise the potential impacts of the new climate files on energy star ratings, new star bands have been added to accredited software tools.
The ABCB is also releasing a new standard for heating and cooling load limits for energy ratings using NatHERS software. These are different to the load limits released as part of the NCC public consultation in August 2021 which are embedded in the NatHERS beta tools. If in doubt, refer to the new ABCB Load Limit Standard.
The new software and updated certificate will also help users and regulators by disclosing the relevant load limit from the NCC Standard.
NatHERS software has been modified to include a thermal bridging function to align with NCC 2022 provisions. The changes prescribe that energy rating calculations for steel-framed construction should match the thermal performance of timber-framed construction.
Find out more about the changes to NatHERS software tools to support the NCC 2022.
Beta versions of software tools now available
The energy efficiency provisions in the National Construction Code (NCC) will be updated on 1 October 2022, with a 12 month transition period.
NatHERS accredited software tools have incorporated new features and data sets to align with these changes. Beta versions of NatHERS software tools can be downloaded to try out some of the new features including:
- New climate files (climate files report here)
- Updated star bands (star bands report here)
- Proposed heating and cooling load limits (heating and cooling limits report here). Note: please refer to the updated ABCB Load Limit Standard).
Industry can use these tools to gauge the star rating impacts on specific types of dwellings.
The NatHERS Administrator has conducted preliminary quality checks on the following Beta versions of software tools*:
- BERS Pro Release v126.96.36.199 BETA 5 (thermal bridging and proposed heating and cooling load limits will be incorporated in subsequent release)
- AccuRate (no longer available).
All material to support commercial tool providers to develop accredited NatHERS tools incorporating the proposed NCC changes is now available. This will support commercial tool availability before the end of the NCC transition period (1 October 2023).
The software tools have not yet incorporated the proposed thermal bridging changes for steel-framed dwellings. However, this Thermal Bridging report shows the expected star rating impacts on homes in different locations.
*Please note these tools are for research and testing purposes only. They cannot be used for regulatory purposes.
All software used to produce NatHERS energy ratings must be accredited in accordance with the NatHERS Software Accreditation Protocol.
There are currently four software tools accredited for use under NatHERS for demonstrating compliance to NCC 2019, all are based on the CSIRO calculation engine, Chenath (v3.21):
- AccuRate Sustainability v2.4.0 (3.21)
- FirstRate5 v5.3.2b (3.21)
- BERS Pro v188.8.131.52 (3.21)
- HERO v184.108.40.206 (3.21)
Key modelling inputs
To ensure calculations are accurate, representative of Australian conditions and are comparable across different types of housing, the Software Accreditation Protocol requires all accredited software tools to meet strict performance standards.
Some of these performance standards include:
CSIRO’s Chenath calculation engine
The Chenath engine has been developed by the Commonwealth Scientific and Industrial Research Organisation (CSIRO). It uses decades of climate data and average user behaviour, among other factors, to predict annual totals of hourly heating and cooling energy requirements for residential dwellings. More information on the Chenath engine can be found in the Chenath repository.
Although it is not a requirement of accreditation, currently all NatHERS accredited software use the Chenath engine to perform the calculations and modelling for a home energy rating.
The Chenath engine was validated in 2004 against the international standard ANSI/ASHRAE 140-2001.
For more information read the Validation of the AccuRate Simulation Engine Using BESTEST.
Including new materials in NatHERS software tools
The Technical Advisory Committee (TAC) periodically meets to consider whether new materials and products should be included in the databases of the NatHERS accredited software tools. As with software updates, the TAC’s recommendations are provided to the NatHERS Steering Committee for approval before the new materials are included.