This video from the NCC 2022 Webinar Series held in March 2023 covers the changes to the NCC and NatHERS tools in NCC 2022.
Clare: Hi, and welcome to this presentation on NCC 2022 and the NatHERS tools. I'm Claire Wright, your host.
I'd like to acknowledge the traditional owners of the lands on which we produced this presentation, the Ngunnawal peoples, and the traditional owners of the land where you are viewing this presentation. I pay my respects to their Elders past and present and recognise their culture as the longest living culture in the world.
Today's presenter is Leonie Wilson, Leonie works in the team that manages the implementation of the Nationwide House Energy Rating Scheme or NatHERS. Her work involves overseeing the administration of the NatHERS software tools and the related policy and governance aspects.
Before we hand over to Leonie, I'd like to cover off the learning outcomes for this presentation. After the session, the aim is that you'll have a better understanding of the relationship between the National Construction Code and NatHERS and learn the following.
First, be able to describe the changes to NCC 2022 as they relate to NatHERS. Interpret and understand some of the related NCC provisions. And lastly, identify when these provisions will be adopted. Now, I'll hand you over to Leonie who will take you through the content –
Leonie: Today I'll be covering how the NCC and NatHERS work together for energy efficiency of homes, starting with NCC 2022 changes related to NatHERS, updates to NatHERS because of these changes, including the new Whole of Home changes, and then information about adoption and where to find more.
First, I'm going to take you through the NCC 2022 changes and how they relate to NatHERS.
As you may be aware, Australia's energy system is undergoing a fundamental transformation, and managing energy demand is a critical part of this change. According to the International Energy Agency Sustainable Development Scenario, energy efficiency represents more than 40% of the emissions reduction needed by 2040.
There is a commitment to reduce Australia's greenhouse gas emissions to 43% below 2005 levels by 2030, and net greenhouse gas emissions to zero by 2050.
The National Energy Transformation Partnership and supporting strategies will support collaborative efforts across governments, energy market bodies, and others, to increase the understanding of energy demand to inform energy planning and investment.
The NCC and NatHERS are playing an important role supporting this work and major transition.
Changes to the NCC and NatHERS were agreed by energy and building ministers last year, as part of the trajectory for low energy buildings and national plan for zero energy and carbon-ready buildings.
You may be aware that thermal ratings are increasing from six to seven stars, and a new Whole of Home energy rating, which considers energy used by major appliances such as heating, cooling, hot water systems and pool and spa equipment, as well as onsite energy produced via solar PV. Thermal bridging requirements are also new for the NCC 2022.
So why the changes? While poorly designed and constructed homes are wasting far too much energy, we can help avoid this by guiding better design and construction through increasing energy efficiency minimum standards for new homes and apartments. This will reduce energy demand now and into the future for the entire life of the building.
And for the first time, NatHERS is providing new information for households on what appliances have the biggest impact on their energy bills and carbon footprint.
This all adds up to more comfortable homes with onsite energy generation, and more energy efficient appliances, with less need for heating and cooling and lower household energy bills.
This brings me to how NatHERS fits into the changes for NCC 2022.
To start with, the NCC performance requirements in NCC 2022 include a stringency increase to seven star or equivalent, as well as being expanded to cover energy usage. NatHERS is still referenced as a deemed-to-satisfy, or DTS pathway as normal but has also been included as a new DTS pathway, for the new NCC Whole of Home performance requirement.
You may have noticed the NCC has updated the clause references from previous years as well, so the references might be a little different than what you're used to.
This flow chart [04:20] shows how the NatHERS compliance pathway for homes fits into NCC Volume Two and the relationship it has with the performance requirements.
In NCC 2022 Volume Two, all relevant clauses for the NatHERS compliance option are consolidated into Specification 42.
The star ratings required in specification 42, clause S42C2, for heating and cooling loads have been changed to reflect the stringency increase for NCC 2022.
The split heating and cooling load limits have been updated, which is included in the next slide.
S42C3 net equivalent energy usage is required if you will use house energy rating software, i.e NatHERS software, to meet the newly introduced Whole of Home requirements. I'll discuss this shortly in the compliance options for the second performance requirement energy usage.
Under S42C4, there are other DTS elemental provisions that need to be met besides NatHERS' star rating and heating and cooling load limits. These include requirements for how thermal insulation is installed and the need for a thermal break in some instances.
This flow chart [05:35] shows how the NatHERS compliance pathway for individual apartments fits into NCC Volume One and the relationship it has with the performance requirements.
The NatHERS pathway in NCC Volume One is an existing compliance option, and practically speaking, the way it operates is broadly the same as under NCC 2019, with some minor changes consistent with the NatHERS pathway in NCC Volume Two. The stringency has increased to reflect the increase in house energy efficiency for NCC 2022.
NatHERS also now incorporates a Whole of Home rating tool that you can use when you are showing compliance with the energy usage performance requirement, J1P3. NatHERS Whole of Home provides a score out of 100 for an individual sole occupancy unit, with the NCC requiring that each apartment achieve a score of no less than 50.
As with NCC Volume Two, the NatHERS pathway by itself is not sufficient to show compliance with J1P3. You'll still have to demonstrate elemental energy efficiency requirements for both air conditioning and ventilation, including equipment servicing the apartment and lighting. This can be done through parts J6 and J7 which were known as J5 and J6 in 2019.
For class one buildings, the NCC 2022 requires a minimum rating of seven stars to be achieved. Those some areas may be allowed to claim an additional credit. For example, outdoor living areas in climate zones one and two may claim a half of a full star credit if certain conditions are met, reducing the minimum rating to six or six and a half stars. There are also updated heating and cooling load limits that match the increased minimum star rating. The Whole of Home requirements are that you attain a rating of 60 out of 100. More details about the
Whole of Home ratings are covered later in this presentation.
There are some specific changes and updates to Class two buildings, with an individual apartment requiring a rating of six stars, but the average across the whole building is required to be seven stars.
There are also updated heating and cooling load limits, like class one dwellings. For Whole of Home, every apartment must rate at least 50. There is no building average for Whole of Home. Every apartment must meet the same target.
Now I'm going to take you through how NatHERS is supporting the recent changes to National Construction Code NCC 2022.
The climate files that are used to calculate thermal star ratings for NatHERS have been updated with more recent and accurate weather data. This is an important improvement to NatHERS, as the climate interacts with the design features of a building to determine the amount of heating or cooling needed to keep the house comfortable. The more accurate the climate data, the better the information supplied to inform the building's design and features.
The star bands, which indicate the amount of energy used for each star rating, have the potential to be impacted by the new climate files. As a result, the star bands have been recalibrated to minimise any impacts. This recalibration ensures that no particular dwelling will be disproportionately impacted by the updated climate files.
As a result, the majority of dwellings will on average have no change to their star rating. Individual dwelling designs may show a small increase or decrease, but the level of impact is well within the range of normal that is expected.
The ABCB heating and cooling load limit standard for NatHERS has also been updated for NCC 2022. The standard has slightly tougher load limits, reflecting in part the NCC's increase from six to seven stars. The load limits also are adjusted to reflect the changes to NatHERS star bands.
NatHERS has also made some adjustments to improve awareness and accessibility of the standard for assessors and certifiers at key stages of the building design and approval process.
NatHERS software has been modified to look up the relevant load limit in the standard and alert assessors when a design is not meeting the requirements.
The NatHERS certificate has also been modified to show the relevant NCC split load limits next to the predicted heating and cooling loads of the rating. This approach will allow users of the certificate, such as building certifiers, to quickly assess whether the NCC load limits are met, while also allowing them to consider local variations.
The final accredited software tools will have the updated load limits.
The thermal bridging requirements for residential buildings are also updated in NCC 2022. As thermal bridging can significantly reduce the effectiveness of insulation if it is not accounted for. Thermal bridging is the movement of heat across an object that is more conductive than the materials around it. This effect is more pronounced with metal frames.
NatHERS has worked with CSIRO to develop a thermal bridging capability that aligns with the NCC 2022 requirements. This includes applying thermal bridging to metal frame constructions and aligning them with their timber frame equivalents. Thermal bridging calculations will only apply to repeating metal frame elements, for example, joists and studs for floors, walls, and ceilings. Default values will be used when the precise framing specifications are not provided.
It is an NCC requirement that the thermally bridged metal frame constructions achieve the same thermal performance as similar timber frame constructions.
To offset the negative effects of thermal bridging on the thermal performance in NatHERS, other elements of the home's design can be improved. Please refer to the NatHERS website for further information on thermal bridging. This includes a report with details of the thermal bridging research that was undertaken.
NatHERS software is being upgraded to support the new NCC energy efficiency requirements. We are working with commercial software providers to update and re-accredit tools for use as soon as possible. In the interim, assessors can use the endorsed beta tools to gauge the impact of updates and new inclusions and familiarise themselves with conducting Whole of Home assessments.
Building for seven stars does not have to be costly or complicated. Simple design features and material choices can make a big difference to a home's energy efficiency and its energy rating.
Correctly applying the principles of passive solar design will have the largest impact on a rating at the least cost to assist reaching the new seven star requirement.
This includes building for the local climates and using sun control mechanisms to provide appropriate shade and solar access as required. This could be, for example, to let in the winter sun and block out the summer sun.
Also correctly orientating the design and the zoning spaces so the main living areas have a northerly orientation, will make a significant difference to a home's thermal performance and its star rating.
Optimising the size, location, operability and shading of glazing is another important consideration to take into account. This could be to enhance cross-ventilation or by strategically limiting glazing to the east and west orientations when appropriate. Improving the glazing is also something worth considering. NatHERS includes both default and custom window options. Generally choosing default windows will usually result in a lower rating, so we recommend switching to a custom window, where all the specifications are known. This allows for greater accuracy.
Consideration should also be given to the color of the roof, window frames and walls.
Adding internal ceiling fans where appropriate and increasing the R value of wall, floor and ceiling insulation, can also assist in improving your rating.
In the second half of this session, I'll now cover the expansion of NatHERS to perform Whole of Home assessments in more detail and how NatHERS fits into the NCC 2022 changes.
In line with government policy, the NatHERS team and industry have been working on expanding NatHERS from assessing the thermal performance of buildings, to assessing the whole system of energy use in the home.
In a nutshell, this means bringing appliances into NatHERS. NatHERS is now able to assess the impact of those appliance choices.
As NatHERS is a very common pathway used for demonstrating compliance with the energy efficiency requirements for the NCC, the focus has been to align NatHERS updates with the NCC 2022 scope. This means we have targeted the same fixed appliances that the code has referenced, covering heating and cooling, heated water, lighting, pool and spa equipment, and onsite generation.
As I touched on earlier, the thermal star rating will sit alongside the Whole of Home performance rating on the new NatHERS certificates. It is a score out of 100 which includes an assessment of the energy required for the whole home.
These changes will help homeowners make decisions on the most energy efficient appliances and products to include in their new home. They also encourage home builders to consider the efficiency of the appliances they recommend to clients.
NatHERS assessments also help compare the performance of different home designs, so clients can find the design best suited to their needs, the climate and their block.
Using NatHERS we easily see how the design meets or exceeds the minimum standards and ultimately design and build homes that have little to no energy bills.
While not required by the NCC, the NatHERS administrator encourages using a NatHERS accredited assessor and engaging them early on in the design process. This is so they can provide the best advice on how to design a home to reduce its heating and cooling needs and improve the Whole of Home rating if required.
For example, to improve the Whole of Home rating, a NatHERS accredited assessor might recommend using higher efficiency appliances or adding solar PV. Higher efficiency versions of the appliances that have been specified will simply use less energy and improve the rating. Likewise, having solar means importing less energy from the grid and also allowing for credits for exports that help offset the energy use depending on where you are.
If those aren't creating the change your clients want to see, a NatHERS accredited assessor might advise switching to a different appliance technology, if that's going to work for your client. Or they might suggest shifting some of the energy used during those expensive early evening peaks to a cheaper time. This can be done by facing some of the solar PV panels towards the west, allowing the system to generate more electricity later in the day, or by adding a battery.
Just like in NatHERS' thermal assessments, there are elements that you won't be able to change. This is because while there are things that are good for improving energy efficiency, they're also very difficult for a building certifier to check and enforce through their compliance checks.
As an example, occupant behaviour has a large impact on energy consumption in a home. Taking shorter showers or turning on a heater at a lower temperature than what is assumed in NatHERS, will reduce energy usage, but this cannot be checked by a certifier so will not be considered in this rating.
We also need to make sure that ratings are consistent and there is a fair and level playing field for industry. This means that there are assumptions that need to be made so that we can compare different homes equally.
So, what do you need to do now to prepare for the energy efficiency changes?
The next section of this presentation covers advice about transition and adoption dates.
If in doubt, we recommend that you check with your local building authority.
We are also rolling out training for accredited assessors from this month. Sign up for sessions from March through to August.
Right now, all you need to do is keep an eye on the NatHERS website, and if you have not already done so, sign up for our newsletter to access the latest information including software accreditation updates, assessor fact sheets with practical guidance on building for seven stars.
The new ratings are supporting industry and consumers to design and build homes that meet minimum standards and exceed them if they wish.
If you would like any more information, please visit the websites listed on this slide.
This is a big change for NatHERS and cannot be done without the engagement and support from all of you.
Clare: Thanks for that Leonie. We hope everyone found that informative.
That brings our presentation on the changes to NatHERS and NCC 2022 to a close.
Thanks for watching.