I would like to take a bit of a detour today, away from the recent focus on Chinese vernacular architecture and into some ‘talking shop’. This is prompted by the recent adoption (on May 1st 2023) of the new National Construction Code, which replaces the previous NCC released in 2019.
For those unfamiliar with the NCC, the Victorian Building Authority website provides this explanation:
“The National Construction Code (NCC) sets out the requirements for the design and construction of buildings in Australia, including plumbing and drainage work. It sets the minimum required level for the safety, health, amenity, accessibility and sustainability of certain buildings.”
The NCC has previously been comprised of three volumes:
Volume One, The Building Code of Australia Volume One, which covers mainly Class 2-9 structures;
Volume Two: The Building Code of Australia Volume Two, which covers Class 1 and 10 structures; and
Volume Three: The Plumbing Code of Australia.
The 2022 NCC retains this basic three-volume structure, but also introduces significant changes and additions to the organisation and content of the Code.
The deemed-to-satisfy solutions for Class 1 (basically houses) and Class 10 (garages, carports and the like) structures, which used to be contained in Volume Two, have been split off into a new document, the ABCB (Australian Building Codes Board) Housing Provisions Standard 2022; Volume Two now contains only the performance solutions for Class 1 and 10 structures.
There is a whole new Section to the Code, “Liveable housing design,” which is presented in both Volume One (as Part G7) and Volume Two (as Part H8), and also in its own dedicated Standard referenced in these Parts: the Australian Building Codes Board Liveable Housing Design Standard 2022. This Standard contains new requirements (to come into effect in Victoria on October 1st 2023, after a five-month transitionary period where adoption is optional) intended to ensure that new dwellings “better meet the needs of the community, including older people and people with mobility limitations.” It is an adaptation of the ‘Silver’ level requirements of the Liveable Housing Design Guidelines (LHDG) 2017, but essentially makes mandatory in private dwellings certain design elements that until now had been optional: things like step-free access to dwelling entrances, minimum clear widths for openings and corridors, accessible bathrooms, and the like. Previously such measures were generally only required in public buildings, with the specifics given in Australian Standard 1428 - Design for access and mobility.
The other major change to the Code is an increase in the stringency of water use, energy efficiency (to the tune of around 30%) and condensation mitigation requirements. The new energy efficiency requirements are contained within Volumes One (Section J) and Two (Part H6), and also in the Standards referenced therein: the ACAB NatHERS (Nationwide House Energy Rating Scheme) Heating and Cooling Load Limits Standard 2022, and the new ACAB Whole-of-Home Efficiency Standard 2022. The NatHERS scheme is used to provide a streamlined pathway to achieving the energy efficiency standards required by the NCC, and it assigns a star rating to new dwellings; the minimum rating required, previously six stars, is now seven. Likewise, although NatHERS has contained heating and cooling load limit provisions since 2019, those required by the 2022 edition are stricter.
The new Whole-of-Home Efficiency Standard, as explained in its introduction, “provides a holistic assessment of the energy performance of a dwelling, covering both thermal performance and domestic services. To meet the WOH requirements, the net equivalent energy usage of a dwelling must not exceed a certain allowance.” This is in contrast to the approach adopted by the NCC and NatHERS until now, which has been more focused on managing “heat transfer through the building envelope to separately minimise heating and cooling loads.”
All this represents significant complexification and growth of the Code over the previous edition, and is indicative of a larger general phenomenon. Next week, I would like to explore its implications from a more abstract and holistic perspective, and consider what it means to be ‘green’.