The Australian Building Codes Board (ABCB) has been directed by the Building Ministers’ Forum (BMF) to investigate possible changes to the National Construction Code’s (NCC’s) energy efficiency provisions, with an emphasis on residential buildings in NCC 2022.
This work is to be carried out in consideration of the Council of Australian Governments (COAG) Energy Council’s Trajectory for Low Energy Buildings (the Trajectory). The Trajectory proposes incremental changes to the NCC to reduce the operational energy use and associated greenhouse gas emissions of buildings.
To commence this process, the ABCB released a Scoping Study titled, Energy efficiency: NCC 2022 and beyond, for public comment. The Scoping Study outlined a possible approach and scope of the project, with a particular focus on the 2022 version of the NCC (NCC 2022). The Scoping Study was prepared in consideration of the overarching objectives of the Trajectory, which include reducing energy bills; improving the reliability of energy networks; reducing greenhouse gas emissions; and to providing industry with certainty about future regulatory changes.
A total of 135 submissions were received on the Scoping Study from a broad range of individuals and groups. The largest number of submissions came from respondents who identified themselves as specialists in energy efficiency, designers, product suppliers, builders and engineers. A quantitative and qualitative analysis of the submissions was undertaken to inform this report.
For residential buildings, the two options proposed in the Scoping Study attracted similar levels of support. However, questions were raised about their feasibility, particularly Option 1, which proposes net zero annual energy use (NZRE) for the regulated building services. A whole-of-house approach, which allows trading between building elements, was well supported on the proviso that there remained a minimum level of thermal comfort that could not be traded.
The proposed quantified Performance Requirements for residential buildings were well supported by respondents. However, a number of respondents raised concern about their complexity, as well as the complexity of the residential changes in general. Concern was raised that this could increase the need for specialist energy efficiency consultants. The proposal to apply a threshold to the elemental DTS Provisions also attracted considerable attention, although opinions were divided, mostly between having a smaller 120 m2 threshold and none at all. There was also support for extending the elemental DTS Provisions to Class 2 sole-occupancy units (SOUs).
Respondents overwhelmingly supported the recommended baseline levels of energy efficiency for residential building services specified in the Trajectory. There was also support for the current Nationwide House Energy Rating Scheme (NatHERS) compliance pathway, as well as its possible expansion to accredit whole-of-house tools. The NSW Building Sustainability Index (BASIX) also received relatively strong support as a whole-of-house tool.
For both commercial and residential buildings, provision for the future installation of on-site renewables and electric vehicle (EV) charging was supported. The concept of the NCC being technology and fuel neutral attracted differing views, with some respondents arguing that gas should be phased out. There was also some concern raised about the impact of increased uptake of on-site renewables on the electricity network.
For commercial buildings, respondents expressed broad support for further investigating the areas identified in the Scoping Study. This included the use of future climate data, expanding the Verification Methods, refining the thermal bridging provisions, accommodating vertical shading, and reviewing the role of on-site renewables.
Responses were, however, divided on the treatment of commercial buildings with low volume-to-surface area ratios, but the other areas identified were all generally supported, albeit with some caveats.
Information was provided by a number of respondents about current market behaviour, particularly in relation to residential buildings. Some respondents suggested there is no need for further regulation given the current and likely uptake of energy efficiency and on-site renewables. It was also suggested that the regulation impact analysis of any proposed changes must consider split incentives, property rights and equity issues. The increasing size of dwellings was also raised as working against efforts to increase energy efficiency.
The responses to the Scoping Study will inform the investigation and development of the NCC energy efficiency provisions in 2022 and beyond. For NCC 2022, the specific approach outlined in the Scoping Study, as modified by applicable responses, is repeated below.
Residential buildings
For residential buildings (houses and apartments), two sets of NCC provisions (or options) will be developed and tested through regulation impact analysis to determine the appropriate option for adoption in NCC 2022. The two options are as follows:
Option 1 involves a set of provisions which would result in residential buildings having a level of thermal comfort equivalent to 7 stars NatHERS and NZRE, (based on the societal cost of energy) for the regulated building services, i.e. space conditioning, heated water systems, lighting and pool and spa pumps.
Option 2 involves a set of provisions which would result in residential buildings having a level of thermal comfort equivalent to 7 stars NatHERS and a moderate amount of annual energy use for the regulated building services.
The two options will enable a ‘whole-of-house’ approach to be used to achieve compliance. In particular, compliance through Verification Methods (or whole-of-house tools) and, to a limited extent, the elemental DTS Provisions will allow some trading between the energy efficiency of building services, and allow limited offsetting with on-site renewable energy.
Testing the two options will enable the ABCB to identify the most appropriate provisions for adoption in NCC 2022 and whether a transitional period should be applied. If the less stringent Option 2 is chosen, the development of Option 1 will nevertheless provide industry with an indication of the provisions that may be adopted in a future version of the NCC.
Commercial buildings
Given that substantial changes were made to the commercial building energy efficiency provisions in NCC 2019, and with other priorities now taking precedence, the ABCB will investigate more moderate changes in NCC 2022. This may include work that will complement the residential energy efficiency provisions such as research into the grid impacts of increased uptake of on-site renewable energy and research into provisions that accommodate the future installation of on-site renewable energy and EV charging.
More substantial changes for commercial buildings may be considered in NCC 2025. This may involve the same approach used for residential buildings in NCC 2022, i.e. the development of two possible options with one being net zero.
Next steps
In addition to the Scoping Study process, further opportunity will be provided for comment throughout the development of the proposed changes to NCC 2022.
In developing the proposed changes to NCC 2022, the ABCB will also undertake a holistic review of the residential energy efficiency provisions. This will include considering related issues, such as condensation and heat and cold stress. The ABCB will also ensure the residential energy efficiency provisions take account of regional differences.