In a piece of very welcome news, the Australian Building Codes Board (ABCB) is proposing a revision to the 2016 version of the National Construction Code (NCC) which will fundamentally change the way that we certify multi-residential towers against Section J. And not a moment too soon!

The words ‘Existing Verification Method JV3 – Class 2 buildings included in the application provision of the Verification Method as a means to comply with JP1’ has been like music to my ears.

The significance of this is huge. It means that instead of the painstaking NatHERS assessments whereby each apartment is modelled in isolation, potentially you will soon be able to instead model apartment towers in the same way as commercial developments – a holistic, whole-building approach.

This may not seem like a big deal, but honestly, it is great news for all involved in the design process of these towers. In essence, apartment developments are one of the more efficient ways to provide housing from an energy consumption perspective, but the current NatHERS methodology seriously penalises them as it was originally designed for stand-alone houses. Isolated apartment modelling commonly results in the need to install multiple glass specifications across one residential tower due to the site specific idiosyncrasies (for example shading from adjacent structures, varying wind loads and solar exposure). The outcome is often disjointed aesthetics and issues with glass procurement, not to mention potential confusion during the installation.

Undoubtedly the concept that each individual apartment meets the same minimum energy standard is an ideal situation, but it makes no allowance for the actual reality of how hard this is to achieve. Of course roof apartments perform worse than mid-floor due to their increased level of exposed fabric, but that shouldn’t then push the specification of the whole façade, which would need to be done to keep the aesthetics consistent. This proposed whole-building approach is more in line with the energy targets set by other countries around the world for multi-residential towers and I welcome it with open arms.

However, I don’t think the ABCB have got it 100 per cent right...yet. There are proposed changes to the modelling methodology for residential towers only, which would seem to allow an apartment tower in Sydney with 80 per cent of its façade glazed (basically a glass box), to comply with clear glass and no solar control. The solar loads penetrating into a western orientation apartment would be huge and energy consumption would be off the chart, not to mention the impact on thermal comfort.

The good news is that the NCC 2016 is in its draft format and the ABCB are calling to industry for feedback (you’ve got until August 3 to provide comment). This proposed changes to Section J don’t deal will the numerous issues around the quality of apartments, and the JV3 process is far from perfect, but I really feel that this is definitely a step in right direction.

The opportunity may have already been missed for this to impact in Melbourne, but with the predicted future growth in the other major cities, now is certainly the time for change.

  • Hi Jessica,

    How would you amend the requirements for glazing?

    For Sydney, the proposed default requirement for climate zone 5-8 is Total System U-Value of 3.9 Total System SHGC of 0.59, which would be equivalent to a double glazed unit (or very very good low-e). In the whole scheme of things, not too bad?

    Also, as BASIX applies in NSW, would that not mean that is not applicable for NSW at least?

    • Hi Lawrence,

      I'm all for the reference building having set glazing thermal performance, but I feel that if you define these values then you also need to specify how big the windows are as a ratio to the wall. You're right in terms of the U-value of 3.9 being fairly good, but I think the SHGC is of concern. If the reference building had a relatively low window to wall ratio (<50%) then I could accept that the SHGC is high, but with an 80% window to wall ratio the solar load would be very large with this range of figures.

      In terms of BASIX, I'm not sure how it's going to fall. I would hope that there will be an allowance to incorporate this JV3 option rather than continuing to force the NatHERS route, providing design teams the flexibility of choice. Fingers crossed!

  • Jessica
    While you raise some valid points, I do not agree with the basic premise of your argument.
    The draft 2016 NCC has not made any amendments to Part J0.2 which specifies that all Class 2 SOUs are required to achieve minimum NatHERS ratings (6-star average and 5-star worst-case).
    This being the case, my interpretation of the change is that it only allows improved performance in apartments to be offset against other parts of the building, allowing retail or residential amenities to have below-DTS performance. All the points you raise regarding the reference glazing spec remain valid in this context as potentially the reference building construction is well below what actual 5/6-star NatHERS performance would be, reducing the standard of other parts of the building envelope.
    Clearly this is something regarding which the ABCB need to provide clarification.