The NatHERS Administrator is aware many assessors and others in industry are frustrated with the current situation regarding windows in NatHERS tools. We have therefore been working closely with those responsible for managing windows in NatHERS tools as a priority, to resolve the various issues.
The process to improve windows in NatHERS tools is complex, time consuming and involves various stakeholders, particularly as solutions need to be technically implementable and any potential rating or regulatory impacts identified and assessed prior to a change being made.
To keep you informed about where the process is up to, the NatHERS Administrator has provided the following update.
The NatHERS Administrator assisted the Australian Fenestration Rating Council (AFRC) from mid-2018 to work through the large backlog of Window Energy Rating Scheme (WERS) rated windows required to be added to the NatHERS custom window library to bring it up to date. This was scheduled to be completed ready for the November 2018 AFRC custom window update.
However, a number of key issues became apparent during the process of preparing for the November windows update, including having the existing windows data updated by the AFRC without suitable version control to document and manage the changes. Consequently, the NatHERS Administra-tor postponed the November windows update, based on the release of this file creating risks for all stakeholders. The NatHERS Administrator will not proceed with this update until the AFRC have resolved their data management processes.
The NatHERS Administrator and CSIRO are currently assisting the AFRC to implement an adequate version control solution for the next AFRC custom window update. The NatHERS Administrator is also taking this opportunity to work with the AFRC on additional improvements that will benefit all stakeholders. The changes being implemented are:
These changes will require modifications to CSIRO’s Chenath Engine and the NatHERS software tools. At this stage it is estimated these improvements will be available in the second half of 2019.
The NatHERS Administrator is aware there are a number of issues with the NatHERS Default Window Library. Within the limits of the current substitution tolerances, many default windows are a poor match for actual windows currently available on the market.
The NatHERS Administrator initially investigated broadening the substitution tolerance, but found that doing this would have broader regulatory and flow-on implications and there were problems with the data and the way it was produced to enable this to occur. Consequently, the NatHERS Administrator will create a new Default Windows Library that resolves these issues without the need for adjusting substitution tolerances.
A new Default Windows Library will ensure that a better represent-ation of windows currently available on the market are available for selection in NatHERS software tools and should vastly improve its utility. The new library will initially run alongside the existing default window library for a transition period, until the latter is phased out. It is anticipated the new default window library will be incorporated into the NatHERS accredited software tools by mid-2019.
The Nationwide House Energy Rating Scheme (NatHERS) provides homes with a star rating out of ten based on an estimate of a home’s potential (heating and cooling) energy use. NatHERS is administered by the Department of the Environment and Energy on behalf of the states and territories.