by Tony Isaacs and Matthew Graham

06 Nuts & Bolts Nuts&Bolts

Public Comment version of NCC 2022

By Tony Isaacs and Matthew Graham, TASC Members

A summary of changes for NCC 2022 energy efficiency provisions.

The public comment version of NCC 2022 was released on 30 August, including a significant upgrade to the energy efficiency provisions. The Regulatory Impact Statement was due to be released in late September 2021. Comments on the new regulations close on 17 October. The changes are extensive.

To help TPAs understand the new regulation, here is a quick summary from Tony Isaacs who has been working with the ABCB to help develop the energy efficiency upgrades over the last 18 months with assistance from TASC Member Matthew Graham.

The brief for the energy efficiency upgrades arose from the federal government’s Trajectory for Low Energy Buildings, developed and endorsed by the former Council of Australian Governments (COAG) Energy Council. See: https://energyministers.gov.au/publications/trajectorylow-energy-buildings.

Note that issues regarding compliance are a state government responsibility and, while obviously important, are therefore not a part of the current consultation. Requirements for reducing air leakage, such as those in Passive House which require a heat recovery ventilator, were not part of the brief. Summary of changes for NCC 2022 energy efficiency provisions:

• Increase building fabric to 7 star in general for Class 1, with an average of 7, minimum 6 star in Class 2. There is no trade-off between the building fabric and the appliance measures (called Whole of Home). • The ‘Whole of Home’ measures require you to meet an annual energy usage budget requirement using a holistic assessment for heating, cooling hot water, pool pumps, and on-site renewable (PV). It proposes a target of 30 per cent below the energy budget with benchmark appliances in Class 1. Note that GEMS sets the minimum efficiency of appliances. The NCC simply uses the star rating/efficiency of the appliances to calculate the target energy use.

In Class 2, a less stringent Whole of Home option is used (100 per cent of the energy use with benchmark appliances, as opposed to 70 per cent for Class 1) due to the practical limitations around the use of PV in this Class. e.g., Restricted roof area and the relative difficulty in getting the PV fed in ‘behind the meter’ on a unit-by-unit basis. PV will still count towards the calculation of the target where it is possible to install it. Note that common areas of Class 2 are considered as part of commercial buildings, which is out of the scope for discussion for the NCC 2022 residential energy efficiency changes, but is covered by other parts of the NCC, as per NCC 2019.

A Whole of Home elemental provisions calculator is provided so you can see whether you need PV, given your appliance types and efficiencies and, if so, how much. Note that PV is not mandatory, but if you choose to install it, as many Australians are doing, its benefits are counted. (NatHERS will model this directly, see below).

• The ‘metric’ for pass/fail is called Societal Cost. It is just the cost of energy using a time of use tariff, plus a little extra for GHG emissions. You’ll see a more detailed description in the supporting reports that can be downloaded from the Consultation Hub NCC Whole of Home component. (https://consultation.abcb.gov.au/ engagement/ncc-2022-public-comment-draft-stage-2/)

The current NatHERS occupancy pattern is still used to calculate building fabric stars. A more average occupancy pattern is applied to heating and cooling energy to calculate the Whole of Home score to ensure heating and cooling costs are weighted appropriately against other energy costs. The good news from this is NatHERS assessors can, at last, tell their clients that a better NatHERS Whole of Home rating will mean a lower energy bill (on average) than it otherwise would have been. Still some disclaimers, but not as much as it has been in the past.

• Thermal bridging requirements for steel-framed buildings improve steel frame performance to close to timber frames. e.g., Add 10-15mm continuous polystyrene (or equivalent R-value) or R0.6 to the frame only. There are minimum Total R-value requirements in the elemental provisions, including thermal bridging, but you don’t need to calculate it (using the NZ4214 method) if you pick one of the options in the NCC tables. For those up to date with thermal bridging building science, there is an ISO standard that might be technically superior to the NZS standard, but it would need to be referenced by the Australian insulation standard to be included in the NCC. NZ4214 is already referenced in Volume 1. • An updated Verification Method been developed for Class 1, and a new VM, including elemental provisions, has been developed for Class 2. The VM has been developed to ensure that DtS elemental, NatHERS and VM produce approximately equivalent outcomes. Class 2 now has the same three compliance options available to it as Class 1. • Part of the way the VM keeps a more level playing field is that the elemental provisions more closely match

NatHERS 7 stars. It is a closer match to 7 stars than the old elemental matched 6 stars. It does this by: • Specifying insulation levels in tables that take into account a wide variety of conditions. e.g., For roofs: the colour, presence of foil in the roof, the amount of attic ventilation (now calibrated to replicate NatHERS Vented roof conditions), and whether there is bulk insulation under the roof. The tables are more complex than previous insulation requirements, but all the clauses for dispensation for wall R-values are deleted, so some of the previous complexity has been removed. You can still use a concrete block wall in hot climates without insulation, but it will need to be a light colour and/or well shaded. Similarly, an uninsulated brick cavity can be OK in Perth with more climateappropriate colour, height, and shading properties.

The insulation values all link back to NatHERS results, so it is no free pass. That is, in part, why they are more complex – it’s the only way to be consistent with NatHERS and not require crazy high R-values.

• The Glazing calculator has been calibrated to give a pass for a 7-star dwelling with the average heating and cooling load in a particular climate. To achieve better alignment with NatHERS required adding more data inputs. e.g., floor covering (tiled floors on slabs do better), window frame colour, whether the window is in a bedroom or utility space, etc.. You no longer need to do two glazing calculators for two-storey houses but do need to specify if the window is on an upper floor. Class 2 now has a glazing calculator. • Minimum requirements for ceiling fans in Climate Zones 1, 2 and 3, and in living zones in climate zone 5 in NSW and Qld. • The Whole of Home measures and thermal bridging will be included in the NatHERS tools. Please note that the NatHERS administrator is working on incorporating thermal bridging and whole-of-home into NatHERS. Nothing has been endorsed nor formalised yet but is in development. NatHERS tools with these upgrades will be available early next year.

And NatHERS has upgraded the weather data to better represent the climate conditions in each climate zone. So what worked at 6 stars is probably +/- 0.2 stars now. The 10-star level has been recalibrated and demonstrated to be achieved in all 69 climates using a three-bedroom single-storey Design for Place house (https://www. yourhome.gov.au/house-designs). This means that the MJ/m2 for 10 stars has been increased. The 10-star increase flows through to 9, 8 and 7 stars, so 7 stars isn’t quite as challenging as it used to be, particularly in hot, humid climates.

Postscript:

CSIRO has also released weather data files for NatHERS tools including the impact of climate change. They are not part of the new regulations or NatHERS itself but allow the impacts of regulation to be evaluated into the future. Files are available for 2030, 50, 70 and 90 under three warming scenarios each. See: https://ahd.csiro. au/other-data/predictive-weather-files-forbuilding-energy-modelling/.