- Owners and Builders
It has been brought to the attention of the NatHERS Administrator that there is industry confusion as to how to correctly model obscured glass in NatHERS accredited software tools.
Obscured glass (frosted, fritted, film) is classified as a complex glazing system, which is not yet approved internationally through the National Fenestration Rating Council (NFRC). Therefore, the Australian Fenestration Rating Council (AFRC) are not currently capable of obtaining WERS ratings for these types of products. The custom windows library is managed and provided to NatHERS software tools by the AFRC and is based on WERS ratings.
Given obscured glass products are not in the current Custom Windows library (because they have no WERS rating), the NatHERS Administrator is currently reviewing and updating the NatHERS Technical Note to provide a clear direction for what assessors should do when obscure glass is specified. If using default windows, the best fit window currently available is to select the appropriate default ‘clear’ window option.
It is anticipated that complex glazing systems may be approved internationally through the NFRC and subsequently the AFRC in mid-2019, allowing products like this to be better incorporated into the NatHERS software tools and energy assessment.
Additionally, there is a NatHERS fact sheet available on our website explaining how windows impact on a home’s energy performance and the different types of windows that can be used in NatHERS assessments.