Later this year NatHERS software tool providers will start releasing NatHERS accredited tools that use the new Chenath Engine version 3.21. The Chenath Engine (currently version 3.13) has been developed by the CSIRO, and is used by each software tool to perform the calculations and modelling behind NatHERS energy ratings.
Version 3.21 of the Chenath Engine incorporates improvements to double height void modelling, basement zones and shared wall adjacency in apartment buildings, improved edge slab insulation and waffle pod modelling, and the addition of limestone in the materials list. Tools will be released once accreditation is completed using the 2019 Software Accreditation Protocol.
NatHERS Assessors should transition to the NatHERS accredited tools that use Chenath Engine 3.21 as soon as they become available. However, there will be a period where both Chenath Engine 3.21 and 3.13 based tools can be used.
NatHERS assessors will receive notification from their software tool provider about when the updated tools using Chenath Engine 3.21 will be available for download.
Following extensive review and consultation, the final version of the new NatHERS Technical Note (version June 2019) will be released on the NatHERS website by 31 May 2019. The key purpose of this update was to improve the structure, consistency and clarity of language and to incorporate changes associated with the forthcoming update to Chenath Engine version 3.21.
Assessors must use Technical Note (version June 2019) for all NatHERS assessments commenced from 1 June 2019. For NatHERS assessments commenced prior to 1 June 2019, assessors may instead use one of the previous versions of the Technical Note as outlined below, and make a note in the ‘Additional Notes’ section of the NatHERS Certificate about which version of the Technical Note was used:
Tables 3 and 4 from Technical Note 1 (version 1.2 – 2014) have been added as Appendices (2 and 3) to the new Technical Note (version June 2019). This will enable assessors to meet the new requirements when using software underpinned by Chenath Engine version 3.13.
A draft version of the NatHERS Technical Note (version May 2019) was released on the NatHERS website on 18 April 2019. The final Technical Note (version June 2019) was released on 28 May 2019 and includes a few minor adjustments.
A new NatHERS Certificate is being rolled out by NatHERS software tool providers. This will be accessible through new software tools underpinned by Chenath Engine version 3.21.
Once called the ‘NatHERS Universal Certificate’, it has undergone a major overhaul to improve its structure and usability, and will now be referred to as the ‘NatHERS Certificate’.
A preview of the new NatHERS Certificate will be uploaded to www.nathers.gov.au in the coming months.
To improve the year-round performance of Australian homes, the 2019 National Construction Code (NCC) requires NatHERS assessments to meet separate heating and cooling load limits in many climate zones.
NatHERS tools already calculate separate heating and cooling loads as well as the total combined load and these are displayed on the Certificate in MJ/m2 per annum.
NatHERS assessors will need to check these loads against the split heating and cooling load limit tables in the ABCB Standard to make sure they comply. NatHERS accredited software tools will implement a tick box or prompt to remind assessors to check this requirement.
There is a transition period for NCC 2019 from 1 May 2019 to 30 April 2020 where the current (2016) requirements will still be accepted.
Under the National Construction Code, student accommodation and boarding houses are considered as Class 3 buildings and treated as commercial premises, so they are not subject to residential energy efficiency requirements. However, a recent finding by the New South Wales (NSW) Land and Environment Court has classed some of these buildings as dwellings that are subject to NSW BASIX requirements. This finding has resulted in more NSW Councils requesting NatHERS assessments for such buildings.
NatHERS accredited software tools are intended for rating Class 1 and 2 buildings only. Assessors asked to perform a NatHERS rating on a Class 3 building should follow the rulings of the individual Principal Certifying Authority (usually the local council).