Issue 6 - June 2018


Welcome to the sixth edition of the NatHERS Star.

This edition focuses on the progress of ongoing improvements and updates we are working on for NatHERS.

Update on windows

The NatHERS Administrator is aware many assessors are frustrated with the current situation regarding windows and have been actively working on improvements to address these concerns.

One of the complaints we hear regularly is that the custom windows library is not up-to-date and the window an assessor is looking for is not in the library. This has been caused by the process involved with transferring data from the Window Energy Rating Scheme (WERS) database to the Australian Fenestration Rating Council (AFRC) database (the database used by NatHERS software tools) being very time consuming to transfer. A diagram showing the process involved for custom windows can be viewed here on the NatHERS website.

To resolve this issue, the NatHERS Administrator has been working with the AFRC and CSIRO to overcome the technical issues to data transfer and establish processes that make the data transfer faster and easier for the AFRC to undertake. Recent improvements have made the process twice as fast. The AFRC anticipate the custom window library will be updated in August and we expect these AFRC updates to be incorporated in all NatHERS software tools in November as per the developers' regular update schedule. The NatHERS Administrator is also working with software tool providers to streamline the way windows libraries are updated in each of the tools.

Another complaint we receive is about the lack of clear guidance of substitution rules for custom windows. Resolving this issue is complicated, as any new rules need to be carefully investigated to ensure they are technically implementable, do not place unnecessary burden on stakeholders and any potential rating impacts are identified. As the majority of NatHERS ratings are done for regulatory purposes, changes that could have regulatory impacts also need to be supported by all states and territories. With all this considered, the NatHERS Administrator will be briefing the NatHERS Steering Committee this month about options for new substitution rules and looks forward to implementing the preferred option shortly.

Recognising windows are a source of frustration with assessors, the NatHERS Administrator has prioritised working on these issues in order to achieve the best possible solutions.

Chenath updates for 2019

In line with the 2019 update to the National Construction Code (NCC) there are a number of updates that are planned for the Chenath engine, which improve accuracy of ratings and solve some long-lasting issues with the software. These include:

  • New approaches for:
    • glazed corridors
    • basement carparks in Class 2 buildings
    • double height voids
  • Limestone added to the materials database
  • Improvements to edge batt modelling
  • Updated waffle pod values to represent their true performance

Guidance on how to use the new zones is currently being developed.

These updates will be accompanied by an updated Technical Note and an updated NatHERS Universal Certificate (which is also being updated based on the recent review that is available here)

An updated software accreditation protocol is also being developed to ensure these updates are rolled out uniformly to all tools.

WA climate zones and interactive climate zone map updates

The NatHERS interactive climate zone map is a useful visual representation of the 69 NatHERS climate zones and can be accessed online from the NatHERS website. Work was recently undertaken to update the map in order to ensure it aligns with NatHERS software tools. Unfortunately these updates took longer than expected and the interactive climate zone map was unavailable while the updates took place.

The improved NatHERS interactive climate zone map is now once again accessible online, however as noted in the NatHERS Technical Note v1.2 clause 4.5.4 ‘the NatHERS online Climate Zone map is for assessor reference only and the software selection of climate zone has preference.’ Please continue to use the climate zones as provided in the NatHERS software tools.

The interactive climate zone map can be accessed from the climate zone page of the NatHERS website.

At the same time as updating the interactive climate zone map, work was conducted to align the Western Australia (WA) postcode to climate zone information in NatHERS software tools with the Technical Requirements and climate zone variations outlined by the WA Government. NatHERS accredited software tools will be rolling out the WA changes shortly.

NatHERS Assessor Handbook

The NatHERS Handbook is being developed by the NatHERS Administrator in conjunction with industry experts. It is designed to help assessors navigate the NatHERS assessment process by describing how assessments should be conducted, including the mandatory and recommended steps of the process. The Handbook will present information to assist assessors, regardless of which assessment tool software is used.

The production of the NatHERS Handbook is well underway. Graphic design of about half the handbook is currently taking place and these chapters will soon be available for their first round of review.

The Handbook will be divided into chapters based on building and environmental elements, and assessment tool functions;

  • Chapter 1. Before you start
  • Chapter 2. Data entry
  • Chapter 3. Climate, terrain and exposure
  • Chapter 4. Zoning
  • Chapter 5. Floors
  • Chapter 6. Walls
  • Chapter 7. Windows and doors
  • Chapter 8. Ceilings and roofs
  • Chapter 9. Shading and eaves
  • Chapter 10. Finalising the assessment

Split heating and cooling loads for NCC 2019

In addition to the above Chenath updates, you may be aware the Australian Building Codes Board (ABCB) recently sought feedback on changes to the NCC 2019 that would set maximum heating and cooling load limits for the NatHERS pathway in the NCC. The goal of setting maximum heating and cooling load limits is to improve the performance of new homes in Australia. The NatHERS Administrator is currently working through the implementation of this change and advice on any changes to assessments will be provided to assessors before changes become live. For more information about the work already undertaken on split heating and cooling load limits, have a look at the ABCB report.

Trajectory for Low Energy Homes and NCC 2022

In late 2018 the Council of Australian Governments (COAG) Energy Council will consider a trajectory for low energy homes, including potential energy efficiency changes for the 2022 update of the NCC. The Trajectory is a collaborative project of the Commonwealth, State and Territory Governments.

Should the COAG Energy Council agree to NCC changes, the Building Ministers Forum (BMF) will be asked to task the ABCB with implementing potential changes through its NCC 2022 update process, including conducting a Regulatory Impact Statement (RIS).

On 27 April 2018 the Building Ministers Forum announced that the ABCB 2018-19 work plan will include the development of energy efficiency measures for residential buildings.

The Trajectory for Low Energy Homes forms part of Measure 31 of the COAG Energy Council’s National Energy Productivity Plan 2015-2030 (NEPP). The NEPP provides a framework and an initial economy-wide work plan designed to accelerate action to deliver a 40% improvement in Australia’s energy productivity by 2030.

Stage 1 and 2 of the Trajectory involved a research project in collaboration with AECOM, which considered a ‘whole of house’ approach to achieving net zero energy/carbon buildings for new and existing dwellings. The research project analysed existing residential building typologies (built form, appliances and energy use) and new residential building stocks in each jurisdiction, using modelling by the CSIRO developed AusZEH software. This work found that zero energy/carbon detached homes are cost effective to build today, while further consideration is needed on cost effectively lowering apartment energy usage.

Stage 3 of the Trajectory is now using this analysis to inform more detailed policy development and cost benefit analysis, to develop a trajectory for future residential building energy efficiency reforms, including potentially through the NCC.

A Stakeholder Reference Group (SRG), with over 170 participants, has been established to inform the Trajectory. The SRG has met regularly since December 2017 via teleconferences and workshops in Canberra, Sydney and Melbourne. The next SRG workshops will be held in July.

If you would like to be involved in a workshop and/or be part of the discussions, please email


BDAV 10-Star Sustainable Design Challenge

The 2018 Building Designers Association of Victoria (BDAV) 10-Star Sustainable Design Challenge winner has been announced. ‘Hacksaw House’ designed by Gruen Eco Design in collaboration with Paperbark Design was this year’s winner and was described by judges as “an exceptional and admirable building design with a highly creative and innovative approach.”

The annual Design Challenge invites BDAV members to prepare a residential design for a single dwelling or multi-residential project, across any climate zone in Australia, which achieves a non-regulatory 10 Star energy rating.

The winning design from 2012 ’10 Star House Done Dirt Cheap’ has inspired an alteration and addition project in Canberra. This has been occupied since the Easter of 2017 and came through the first winter without needing the heating turned on. A small amount of cooling was used through the 2017-2018 summer, but it is envisaged that this will be largely unnecessary next year when the clerestory windows are operated to facilitate effective night purge ventilation.

More information about the BDAV 10-Star Sustainable Challenge can be found on the BDAV Website.

Appliance Energy Rating Calculator

The Energy Rating Calculator allows you to compare the energy efficiency of household appliances such as fridges, washing machines, dishwashers, air conditioners, televisions and dryers. The calculator converts the information shown on an appliance’s Energy Rating Label into dollars, so you know how much it will cost to run before you buy it. Check out this short video to see how simple it is to use.

The Energy Rating Calculator is available here:

Your Home

Your Home is currently a Commonwealth Government funded information source or ‘guide’ to building, buying or renovating a home.

In 2017 ACIL Allen was commissioned to undertake a strategic review of Your Home. This review found that Your Home provides information that can be used by the building professionals who consumers interact with, as a means of encouraging behavioural change. Research undertaken for this review suggests that Your Home is unique and stands apart from other information on home design and renovation provided by the commercial world. It is a highly-regarded resource and there is unanimous support for government continuing to maintain it.

Based on these findings, Your Home will be updated over coming months. To view the Your Home resource, visit