NCC 2025 webinar series: Energy efficiency

Thanks, Adrian. My name is Audrey Chen, and I'm one of the directors at the ABCB office. NCC 2025 introduces several major changes to section J of volume one, which applies to commercial buildings. That includes class three and class five to nine buildings such as hotels, offices, retail, hospitals, and schools. These updates are designed to support more cost-effective and technology-neutral pathways toward a net-zero future. The key changes include improved energy efficiency requirements for building envelope and services, required outside renewable energy installation, new measures to support future electrification, making it easier to replace gas-fired equipment with electric system later on. Before we jump into the big changes, there are two minor clarifications for class one buildings worth mentioning. First, clause 13.2.65 has been clarified to specify that it applies only to concrete slab-on-ground construction. A related clarification has also been made in specification 42, clause AS 42 C4.1D, when using Nationwide Housing Energy Rating Scheme NatHERS pathway. Second, NCC 2025 now allows wider overhangs and other deemed to satisfy DTS pathway. If you look at tables 13.2.5A to O, you will see that either maximum overhang limitation has been removed or table note has been added to explain what to do if the overhang exceed previously prescribed maximum. These don't change the actual stringency. They just make the rules clearer and easier to apply. Here's a quick summary of which version of the NCC applies to each building class for energy efficiency. Class one buildings will follow NCC 2025. However, compared with NCC 2022, volume two and the housing provisions remain unchanged apart from the two minor clarifications noted on the previous slide. For a class two buildings, including both the sole occupancy units and the common areas, section J from NCC 2022 continues to apply. There are no provisions in NCC 2025 for this class. NCC 2025 includes a note at the start of section J that states, "For class two buildings, section J is replaced with section J of NCC 2022 amendment two." Class four parts of buildings use NCC 2025 section J, and for class three and classes five to nine, NCC 2025 section J applies. And these are where most of the major changes are, which we'll get into next. Let's start with the changes to the performance requirements in section J. There are two key requirements that have changed for 2025, J1P1 and J1P4. J1P1 covers operational energy use and greenhouse gas emission requirements. J1P4 deals with renewable energy, energy storage, and EV charging. For NCC 2025, J1P1 is now framed as supporting near zero operational energy use and greenhouse gas emission reduction, while still maintain comfort. Compared with NCC 2022, the big shift is in part E. The regulated energy allowance has been roughly cut in half, and the greenhouse gas emissions are now quantified for the first time. These changes pick up both improved energy efficiency and the contribution of outside renewables. We've also removed some of the older qualitative text to make the requirement clearer and more focused. J1P4 clarifies that buildings which have already maximized their on-site renewable generation and storage capacity are not required to be designed to accommodate additional future capacity. We'll look at those DTS changes next. There are a lot of updates in this part of the NCC. So, on this slide, we've highlighted only the major changes we will focus on. There are four main areas of significant change. J9D5, solar PV requirements. This is a one of the biggest changes. Buildings now need to install solar PV, not just leave space for it. I will take you through the details shortly. J6D10 and J8, future electrification readiness. These clauses set up buildings so they can easily switch from gas systems to electric systems later on. This includes electrical capacity, switchboard space, risers, and plant space. J4, building fabric, includes improved roof and glazing requirements. Things like higher R values, new thermal emittance rules for roofs, and more strict solar admittance criteria for windows. J6, air conditioning and ventilation are enhanced requirements for chillers, heat pumps, air conditioners, fans, pumps, and cooling towers. These updates are intended to promote more efficient equipment and improved system design. We are not going through these clauses in numerical order. Instead, we are starting with the biggest changes first. That way, we can focus on what will have the largest impact on design and compliance. This slide covers one of the biggest DTS changes in NCC 2025. The new requirements for on-site solar PV in J9D5. In NCC 2022, J9D5 only required buildings to leave space for future solar and battery systems both on the roof and in the switchboard. But in NCC 2025, PV actually has to be installed. There are now two ways to determine how much solar a building needs. First, J9D5 2A use 100% of the available roof area. That means covering all suitable roof space with PV except for areas needed for plant, skylights, gardens, access pathways, or where PV can't work due to shading, steep pitch, or lack of useful space. The clause lists all exemptions directly. The second option is to use J9D5.2B. Size the PV system based on the conditioned floor area. This gives a required array size in watts per square meter of conditioned floor area. This method may suit buildings with small conditioned areas or with large roofs. But for a tall building, it may result in a PV size that physically won't fit in its roof. One advantage of this method is flexibility. The PV doesn't have to be on the roof of the main building. It can be ground mounted or placed on another building on the same site, like at a school campus. On top of this, buildings that use gas must install additional PV under J9D5.3. This actual solar is intended to offset the higher greenhouse gas emission associated with gas. The amount required depends on the building type and location. This slide shows the new requirements in J6D10 and J8 for future electrification. These provisions don't ban gas, but they make it much easier for a building owner to replace gas equipment with electric systems in the future. The idea is simple. If someone wants to switch to electric heating or hot water later on, the building should already be set up to handle that change without major retrofits. What does that mean in practice? There are few key elements. For electrical capacity, the building needs enough spare electrical capacity to run electric heating equipment in the future. Designers must leave physical room in the main switchboard and risers so new circuits can be added later. Buildings must reserve adequate plant space for future electric equipment with enough ventilation openings so heat pumps can operate properly. For hot water system connections, the reserved plant space must have a connection available to the hot water distribution loop. For space heating, the hot water circulation loop has to be capable of operating at a peak water temperature limit. J8 works the same way but focuses on a sanitary hot water as well as pool and spa heating. The NCC doesn't include any requirements for replacing gas cooking equipment. That's outside the scope of regulated energy. Now, let's look at the changes to the building fabric provisions, specifically J4D4 for roofs and J4D6 for wall glazing. First, J4D4 roofs. There are three key changes in J4D4. Higher roof R values for building classes that typically operate overnight. This helps reduce heating and cooling loads more effectively. A new minimum thermal emittance requirement of greater than 0.85. This means low emittance metal finishes like zinc, aluminum, or uncoated metal roofs can no longer be used in the DTS pathway. Stricter solar absorptance limits for metal roofs. When air conditioning plant or fresh air intakes are located on the top of the roof, this prevents the creation of a hot microclimate around the rooftop equipment. Now, J4D6. There are two main updates here. Tighter solar admittance requirements. These requirements are not as tight as those proposed in the public comment draft, but they still deliver a meaningful improvement in energy efficiency. Makes changes to U-values depending on the building class and climate zone. Most of combinations see increases trend to see while others are slightly relaxed. This slide focuses on the important update in J4D6, recognizing the benefits of vertical shading within the DTS pathway. Previously, if a building used vertical shading devices such as fins or screens, designers would typically need to move to a verification method or a performance solution to get credit for that shading. In NCC 2025, that changed. Vertical shading is now formally included in the DTS assessment of solar admittance. This slide covers the changes to part J6, which deal with air conditioning and ventilation systems. There are quite a few updates here. So, I will walk through major ones at a high level. First, J6D11, chillers. There are now two ways to demonstrate minimum chiller efficiency. You can continue using equipment level metrics like in NCC 2022, or you can use a new system level metric called climate specific part load value. This allows designers to assess how an entire chiller plant performs as a system, not just as individual units. Next, J6D10, heat pumps for space heating. There are new minimum efficiency requirements for four pipes chillers and air-to-water heat pumps. These requirements cover both heating and cooling operation. J6D12, air conditioners. There are increases in stringency for unitary systems like package units and split systems. The metrics are aligned with minimum energy performance standards, MAPS, for simplicity, but the actual performance targets are higher. For fans, pumps, and cooling towers, the NCC now requires variable speed capability across a wider range of applications, improving part load performance. J6D9, refrigerant pipework insulation. These requirements have actually been relaxed slightly because refrigerant is now treated as a cooling fluid only, not a heating fluid. This often needed a R value for small pipes. J63 controls. There are updates to air flow modulation and zone design to support more efficient operation. This slide includes some other changes in section J. First, J7 lighting controls. The lighting control provisions have been updated to be broader and more flexible. This means designers have more options for meeting control requirements, such as using different combination of sensors, timers, or automated systems that still achieve the same energy efficiency outcomes. Next, J9 energy monitoring systems. There is now an optional pathway through J9D3 for an environmental management information system. Now, let's look at updates to the verification methods in section J. These sit alongside the performance requirements and the DTS provisions. And there are some important changes for 2025. First, J1V1 National Australian Built Environment Rating System NABERS targets. All of NABERS rating targets have been increased. This aligns with stronger performance requirements in J1P1 and ensures that verification method reflects current expectations for energy efficiency. Next, J1V3 simulation requirements. There are two key updates here. Apply future climate files as required by specification 34. Doing so ensures that the design reflects the climate scenarios used to establish the 2025 provisions and remains consistent with the NCC intended assumptions. There is now a 3% performance margin between the proposed building and the reference building when assessing building services. This margin helps account for modeling uncertainty and makes approach more consistent with other simulation-based verification methods. Finally, thermal comfort metrics have been revised. Predicted mean vote PMV isn't always appropriate for all occupancy types. So, the NCC now uses simpler metrics based on dry bulb temperature, all zone loads. As we wrap up, we've covered just the major updates today. You can find more detailed information about NCC 2025 in our resource library online. I also want to point you to a few helpful resources that will guide you through the energy efficiency changes in more depth. The NCC 2025 commercial energy efficiency handbook gives a detailed explanation of the provisions and how to apply them in practice. Worked examples cover building envelope, fans, chillers, and PV and show step by step how to apply the new DTS requirements. The four case studies look at complete building designs, and show the overall impact of the 2025 changes. The decision regulation impact statement for commercial energy efficiency sets out the policy background and the evidence base behind the changes. That concludes the presentation. Thank you for listening. If you have any questions, please stay for the Q&A session.