by
Sustainability Victoria Energy Software Team | Mar 10, 2023
Outline of the NatHERS software accreditation process
Every three years, all NatHERS (Nationwide House Energy Rating Scheme) accredited software tools need to complete the NatHERS software accreditation process to align with the most recent National Construction Code (NCC) updates. This process ensures that all software tools maintain alignment to the benchmark tool (AccuRate) in regard to software functionality, thermal modelling results and certificate outputs.
In 2022, the NatHERS Administrator introduced the Whole of Home rating, which measures the energy use of the whole home including appliances, solar PV and batteries. This new inclusion has added additional requirements to the software accreditation process.
Sustainability Victoria’s Energy Software team is currently completing the software accreditation process for the FirstRate5 thermal tool, and extensively updating the FirstRate5 Whole-of-Home Pilot Tool so it can be submitted for NatHERS accreditation.
Update on the accreditation of the FirstRate5 Thermal Tool
Sustainability Victoria (SV) is finalising the implementation of software enhancements in the FirstRate5 thermal tool so it can be submitted to the NatHERS Administrator for accreditation. The software testing is progressing well, and SV is confident that the FirstRate5 thermal tool will successfully pass the NatHERS accreditation process once submitted.
Most software changes being made to the FirstRate5 thermal tool are minor in nature, with the more significant changes being:
- The ability to specify thermal bridging for steel framed houses;
- Updated climate files and star bands;
- Updated ABCB heating and cooling load limits.
Further information about how the NatHERS Administrator has managed the impact updated climate files will have on star ratings can be found on the NatHERS website.
Update on the accreditation of the FirstRate5 Whole of Home Tool
In 2021, SV released the FirstRate5 Whole-of-Home Pilot Tool. It was developed to help thermal performance assessors become familiar with undertaking a Whole of Home assessment and demonstrate to the broader building industry the viability of a Whole of Home rating tool. The pilot tool uses provisional calculation methodologies that were available at the time.
The NatHERS Administrator has now released the final approved calculation methodologies for Whole of Home software tools that will assess compliance with NCC 2022. Key updates to the calculation methodologies are as follows:
- The updated NCC 2022 climate files will be used to generate the heating and cooling loads.
- A new blended occupancy profile will be used.
- Users will need to individually allocate each FirstRate5 zone to a specified heater and cooler. Unallocated zones will be assigned a default heater/cooler.
- The PV module has been extensively updated and additional information, such as solar panel pitch and azimuth, will need to be specified.
- The calculations for solar and heat pump water heaters have been updated. Users will now need to specify the number of STCs the chosen water heater is eligible for.
Now that these final requirements have been released, the SV Energy Software team is updating the calculation methodologies used by the pilot tool so the results generated will align with the NatHERS Whole of Home benchmark. SV will submit an updated FirstRate Whole of Home Tool for NatHERS accreditation as soon testing is complete, and we are confident it will pass the NatHERS accreditation process. The final tool will be released later in 2023.
What will happened with assessments completed in the pilot tool?
The FirstRate5 Whole-of-Home Pilot Tool was developed in 2020/21 using provisional calculation methodologies and was not intended to be used to assess compliance with NCC 2022.
SV is also making significant changes to the pilot tool to incorporate the updated Whole of Home calculation methodologies released by the NatHERS Administrator (e.g., new climate files, new mandatory data entry inputs).
These changes mean it will not be possible to migrate existing assessments completed in the pilot tool into the final NatHERS accredited FirstRate5 Whole of Home Tool. Users will need to import project files into the final tool and complete a new assessment.