The National Construction Code (NCC) 2025 is introducing the most significant overhaul to Section J requirements since NCC 2019. With Victoria adopting the new provisions from 1 May 2026 and New South Wales following from 1 May 2027, the industry is entering a new era of energy efficiency compliance. For developers, architects, builders and sustainability consultants, these changes will influence everything from façade design and insulation selection to rooftop layouts and building services strategies.
More importantly, NCC 2025 signals a clear shift away from relying on offsets and towards designing genuinely high-performing buildings from the outset. Buildings will need to work harder through better envelopes, smarter services and integrated renewable energy solutions. The projects that prepare early will be best positioned to avoid redesigns, control costs and achieve compliance efficiently.
A New Era for Sustainable Building Compliance
The updates to Section J reflect Australia’s broader push towards lower operational emissions and net-zero outcomes. While previous versions of the NCC focused heavily on energy efficiency, NCC 2025 places a much stronger emphasis on measurable greenhouse gas (GHG) reductions and long-term building performance.
For design teams, sustainability can no longer be considered late in the project lifecycle. Early collaboration between architects, ESD consultants, mechanical engineers and developers will be critical to delivering compliant and commercially viable projects.
“Under NCC 2025, compliance is no longer something that can be solved at the end of the project. Building performance must be considered from day one.”
The Thermal Envelope Finally Gets Greater Clarity
One of the more practical amendments is the updated definition of the building thermal envelope.
NCC 2025 now clarifies that internal spaces whose temperatures are primarily determined by external ambient conditions, or where thermal loads and ventilation are not actively considered, may not need to form part of the thermal envelope. Conversely, spaces connected to mechanical ventilation systems, such as toilets that draw exhaust air through door grilles, should generally be included.
While seemingly minor, this clarification addresses a long-standing source of disagreement between consultants and should help create greater consistency in energy modelling and compliance assessments.
“Small wording changes can have a big impact. Greater clarity around the thermal envelope should reduce interpretation differences between consultants and certifiers.”
J1V3 Receives Its Biggest Change Yet
The headline change within NCC 2025 is the overhaul of the J1V3 Performance Solution pathway.
To demonstrate compliance, a proposed building must now show greenhouse gas emissions that are at least 3% better than the reference building. Significantly, rooftop solar offsets can no longer be used to achieve this improvement.
There is an additional requirement that could fundamentally change how Performance Solutions are developed with more emphasis on services. NCC 2025 requires that greenhouse gas emissions from the proposed building’s services are not greater than those of the reference building’s services.
In practical terms, project teams will need to pay far greater attention to:
- Electrical systems design
- Mechanical systems design
- Control strategies
- Building services performance
Rather than compensating for poorer envelope performance through large solar installations, the industry will need to focus on delivering genuinely efficient buildings through high-performing façades, better insulation, improved glazing and optimised services.
This represents a major philosophical shift in how Performance Solutions are developed and assessed.
“The biggest shift in NCC 2025 is the move away from offsetting poor building performance with solar. The focus is now firmly back on designing better buildings.”
Roof Insulation Requirements Are Increasing
The Deemed-to-Satisfy provisions have also become more demanding.
Previously, roof and ceiling insulation requirements were largely determined by climate zone alone. NCC 2025 now differentiates requirements based on both building classification and climate zone.
One notable example is a Class 3 hotel in Western Sydney (Climate Zone 6). Under previous requirements, the total roof R-value requirement was R3.2. Under NCC 2025, this increases substantially to R4.8.
The distinction between Climate Zones 5 and 6 is particularly important for Class 3 and 9c buildings. A Class 3 building in Climate Zone 5 remains at R3.7, while the equivalent building in Climate Zone 6 must achieve R4.8.
That difference is significant and highlights the importance of correctly identifying climate zones at the start of a project. A simple classification error could have major design, material and cost implications.
“Getting the climate zone wrong could have significant cost implications. Early review of project location and classification will be more important than ever.”
Solar Reflectance Index Replaces Solar Absorptance
Another important update is the move from solar absorptance to Solar Reflectance Index (SRI) as the preferred roof performance metric.
SRI is already widely used within sustainability frameworks such as Green Star and provides a more comprehensive indication of how a roof surface responds to solar radiation. The change creates better alignment between NCC requirements and broader sustainability benchmarking systems.
The NCC also introduces more reflective roof requirements where rooftop air-conditioning intakes are present, helping reduce heat gain and improve operational efficiency across mechanical systems.
“The adoption of SRI brings NCC requirements closer to sustainability rating tools such as Green Star, helping align compliance and ESG objectives.”
Façade Performance Standards Are Getting Tougher
Building façades will face increased scrutiny under NCC 2025.
Historically, many Class 5 and 6 buildings worked towards a standard Total U-value target of 2.0. The new code introduces performance requirements based on both classification and climate zone.
For example:
- Class 5 and 6 buildings in Climate Zone 5 must now achieve a Total U-value of 1.9.
- Class 5 and 6 buildings in Climate Zone 6 must now achieve a Total U-value of 1.8.
There is some relief for Class 3 and 9c buildings in Climate Zone 6, where the façade requirement has been eased from a Total U-value of 1.1 to 1.6. (Lower is more stringent)
Nevertheless, the overall direction is clear: stronger façade performance will be expected across most building types. This will likely place greater emphasis on glazing performance, framing systems and thermal detailing
“The building envelope is becoming one of the most valuable compliance tools available to design teams.”
Vertical Shading Finally Gets Recognition
Architects will likely welcome one of the more practical updates within the façade provisions.
Historically, Deemed-to-Satisfy calculations largely focused on horizontal shading devices. Vertical shading elements often failed to receive full recognition despite providing meaningful solar protection.
NCC 2025 introduces a methodology that considers both horizontal and vertical shading elements when assessing DtS façade performance. This may allow projects to achieve compliance with less reliance on heavily tinted glazing and reduce the need to pursue complex Performance Solutions solely to capture shading benefits.
The result is greater flexibility for architects and a compliance pathway that better reflects modern façade design
“This change finally gives architects credit for design features that have long delivered real solar performance benefits.”
EV Infrastructure Requirements Have Been Refined
Electric vehicle infrastructure requirements have also been updated.
One of the most significant changes is the removal of electrical distribution board calculation requirements for basement car parks in Class 2 residential apartment buildings
These provisions now apply primarily to Class 3, 5, 6, 7b, 8 and 9 building classifications. The adjustment simplifies compliance for residential developments while continuing to support the expansion of EV infrastructure across commercial and institutional assets.
“While compliance requirements may reduce for some residential projects, market expectations for EV charging capability will continue to rise.”
Solar Is No Longer Optional
Perhaps the biggest practical change for many projects is the introduction of mandatory solar photovoltaic systems within the Deemed-to-Satisfy pathway.
Solar is no longer simply a useful offset strategy. NCC 2025 now requires minimum photovoltaic installations based on building class and climate zone.
For example, Class 5, 6 and 7 buildings must provide approximately 65W of solar capacity per square metre of conditioned floor area. A 100m² conditioned space would therefore require a 6.5kW solar system.
The requirements become even more stringent for developments that continue to use gas-fired systems. Projects incorporating gas hot water or similar systems must provide an additional 1W of solar capacity per square metre of floor area.
The definition and identification of actual conditioned floor and separation of this from habitable spaces will therefore become important.
This reinforces government objectives around electrification and reducing reliance on fossil fuels within the built environment.
“Solar has officially transitioned from a sustainability initiative to a core compliance requirement.”
The New Rooftop Planning Challenge
NCC 2025 goes beyond minimum solar system sizes.
The code now requires that rooftop areas be utilised for photovoltaic generation wherever practical, with exemptions limited to specific circumstances such as:
- Roof gardens
- Plant zones
- Trafficable roof areas
- Occupied terraces
- Roofs shaded for more than 25% of annual daylight hours
- Roof pitches exceeding 45 degrees
- Areas where solar installation is impractical due to mounting or panel limitations
“Rooftops are no longer leftover space. Under NCC 2025, every square metre of roof area has the potential to influence compliance outcomes.”
This change will fundamentally alter how rooftops are designed and coordinated.
Architects, ESD consultants and services engineers will need to identify rooftop uses much earlier in the design process and clearly define plant locations, access zones, landscaped areas and occupied spaces. Demonstrating shading exemptions may also become an important compliance strategy on some developments.
In short, rooftops are becoming valuable compliance assets rather than leftover space.
“Many projects currently entering planning will ultimately be assessed under NCC 2025. Understanding the changes now can prevent costly redesigns later.”
Looking Ahead
NCC 2025 represents far more than a routine regulatory update. It is a significant shift towards lower-emission, higher-performing buildings and arguably the most substantial Section J overhaul since NCC 2019.
For developers, architects and consultants, the key message is clear: start planning now. The projects that embrace these changes early will be better placed to avoid compliance surprises, reduce redesign costs and deliver buildings that meet both regulatory requirements and future sustainability expectations.
Need help understanding how the NCC 2025 Section J changes will impact your project? Credwell’s ESD specialists can help assess the implications, identify opportunities and develop practical compliance strategies that work for your development.
Paddy Healy
Paddy.Healy@credwell.com.au
Director ESD