NCC 2022 Section J Energy Efficiency: Window and Glazing Compliance Guide for Australian Builders

The National Construction Code (NCC) 2022 represents the most significant change to energy efficiency requirements in Australian building history. For the first time, the minimum NatHERS energy rating for new homes has been raised from 6 stars to 7 stars, and the introduction of the Whole-of-Home framework brings a comprehensive approach to energy budgeting that encompasses building fabric, appliances, and renewable energy systems.

Windows are at the centre of this regulatory shift. As the weakest link in the building envelope, windows typically account for 30 to 50 per cent of total heating and cooling energy loss in a standard Australian home. NCC 2022 Section J (for commercial buildings, Class 2–9) and Part 13 of the ABCB Housing Provisions Standard (for residential, Class 1) establish the specific glazing and window performance requirements that builders and developers must satisfy.

This guide explains the NCC 2022 energy efficiency framework for windows, how to use the ABCB glazing calculator, the Deemed-to-Satisfy (DTS) provisions, thermal bridging requirements, and the compliance pathways available to Australian builders.

1. NCC 2022 Energy Efficiency Framework

Structure of the Code

NCC 2022 energy efficiency provisions are structured differently for residential and commercial buildings:

Volume Two (Class 1 and 10 buildings — houses and sheds):
– Part 13 of the ABCB Housing Provisions Standard
– Part 13.3: External glazing (the residential equivalent of Section J3)
– Part 13 DTS provisions cover building fabric, glazing, building sealing, air-conditioning, ventilation, artificial lighting, and heated water systems

Volume One (Class 2–9 buildings — apartments, commercial, public):
– Section J: Energy Efficiency
– J3: External glazing (for Class 2 apartments and Class 4 parts of buildings)
– J4: Building fabric (including J4D6 facade provisions for wall-glazing construction)
– J5: Building services
– J7: Artificial lighting

The 7-Star NatHERS Requirement

The headline change in NCC 2022 is the increase in minimum NatHERS energy rating from 6 stars to 7 stars for new Class 1 buildings. This represents approximately a 25–30% improvement in thermal performance compared to the previous 6-star requirement.

Windows play a disproportionate role in achieving this improvement. Upgrading from single-glazed standard aluminium windows (Uw ~5.8 W/m²·K) to thermally broken double-glazed Low-E windows (Uw ~1.4 W/m²·K) can improve a home’s NatHERS rating by 1 to 1.5 stars — often the single most effective upgrade available to builders.

The Whole-of-Home Framework

NCC 2022 introduces the Whole-of-Home (WoH) framework for Class 1 buildings. WoH is an annual energy budget approach that considers:

Building envelope (insulation, glazing, air sealing)
Heating and cooling (system efficiency, sizing)
Hot water (system type and efficiency)
Lighting (total installed power density)
Swimming pools and spas (if applicable)
Renewable energy (solar PV, if included)

The WoH framework sets a maximum annual energy use budget, expressed in MJ/m² per year, that varies by climate zone. Builders must demonstrate that the combined energy consumption of all listed components falls within the budget. High-performance windows reduce the envelope’s contribution to the budget, potentially allowing trade-offs against other components — or simply providing compliance headroom.

2. Window Performance Requirements Under NCC 2022

Key Metrics

NCC 2022 regulates windows through two primary performance metrics:

Total System U-Value (Uw): The rate of heat transfer through the complete window system (glass + frame + seals). Measured in W/m²·K. Lower is better. NCC 2022 sets maximum U-values that vary by climate zone, building classification, and glazing area.

Solar Heat Gain Coefficient (SHGC): The proportion of solar radiation that passes through the window as heat. Expressed between 0 and 1. NCC 2022 sets both minimum and maximum SHGC values depending on climate zone and orientation — lower SHGC for hot climates (to reduce cooling load) and higher SHGC for cold climates (to allow beneficial winter solar gain).

Air Infiltration

NCC 2022 also requires windows to meet minimum air infiltration rates as tested under AS 2047. The code specifies maximum permissible air leakage rates, and windows with poor sealing performance cannot be used in NCC-compliant buildings regardless of their U-value or SHGC.

3. Deemed-to-Satisfy (DTS) Provisions for Glazing

Volume Two — Part 13.3 External Glazing

The DTS provisions for residential glazing set maximum aggregate U-values and SHGC limits based on:

Climate zone (eight NCC climate zones, from Zone 1 hot humid to Zone 8 alpine)
Glazing area as a percentage of floor area (larger glazing areas require better performance)
Orientation (north, south, east, west — each orientation has different SHGC requirements)
Permanent shading (eaves, fins, overhangs can reduce the effective SHGC requirement)

The DTS provisions are prescriptive: if your window schedule satisfies the U-value and SHGC limits for each elevation, the glazing component is deemed to comply. Builders can use the ABCB Glazing Calculator (available free from the ABCB website) to verify compliance.

Volume One — Section J3 External Glazing

For Class 2 (apartments) and Class 4 buildings, Section J3 sets similar glazing performance requirements but with different area calculations and compliance thresholds. The NCC 2022 Volume One Glazing Calculator (Class 2 and 4) is the appropriate tool for these building types.

Section J4D6 — Facade Calculator

For commercial buildings (Class 5–9), the NCC 2022 Facade Calculator assists in applying Part J4D6 Building Fabric DTS provisions. This calculator considers:

Window, curtain wall, and glazed door schedules
Whole-of-system glazing U-values and SHGC values
Frame, mullion, and spandrel information
Overhangs, fins, and external shading dimensions
Wall-glazing construction by aspect (single-aspect or multiple-aspect assessment)

A compliant facade calculator result indicates that the wall-glazing construction satisfies the applicable DTS criteria, but other Section J provisions (building sealing, services, lighting) must also be addressed separately.

4. Using the ABCB Glazing Calculator

The ABCB provides free glazing calculators for both Volume One and Volume Two of NCC 2022. These are spreadsheet-based tools that simplify DTS compliance verification.

Step-by-Step Process

Identify the climate zone for your project location using the ABCB interactive climate zone map
Compile the window schedule including:
Window type and configuration
Frame material and profile
Glazing specification (glass type, coatings, gas fill)
Whole-window U-value (from WERS certificate or manufacturer data)
Whole-window SHGC
Window area (m²) for each elevation
Orientation (N, S, E, W, NE, NW, SE, SW)
Enter permanent shading data:
Eave depth and window head height
Side fin projections
Adjacent building or structure shading (if permanent)
Run the calculator — it will determine whether each elevation’s glazing complies with the DTS U-value and SHGC limits
Address non-compliant elevations by:
Upgrading glazing (e.g., adding Low-E coating, switching to argon fill)
Upgrading frame (e.g., switching to thermally broken aluminium)
Increasing shading (e.g., deeper eaves, external blinds)
Reducing glazing area

Common Calculator Errors

Using centre-of-glass values instead of whole-window values: Glazing data must represent total system performance including the frame. Centre-of-glass values overstate performance.
Incorrect facade areas: Missing glazed doors, curtain wall sections, or incorrect wall areas can materially change the result.
Unsupported shading assumptions: Shading should be based on permanent, documented building elements. Vegetation and moveable blinds cannot be relied upon.
Inconsistent schedules: The drawings and specifications must match the calculator inputs. A technically correct calculation is invalid if the drawings specify different products.

5. Thermal Bridging Provisions

NCC 2022 introduced new thermal bridging mitigation provisions that are particularly relevant to aluminium window systems.

What Is Thermal Bridging?

A thermal bridge is a path through the building envelope where heat conducts more readily than through the surrounding insulated areas. In aluminium window systems, the frame itself is a thermal bridge — aluminium conducts heat at approximately 200 W/m·K, compared to insulation at approximately 0.04 W/m·K.

NCC 2022 Requirements

NCC 2022 requires that thermal bridges in the building envelope be accounted for in energy efficiency calculations. For windows, this means:

U-values must be whole-window values (including frame), not centre-of-glass values
Thermal break frames may be required to meet U-value limits in cool and mixed climates
Installation details must address thermal bridges at the wall-frame junction

The ABCB commissioned a Review of Thermal Bridging Mitigation Provisions and Thermal Break Provisions (published December 2023) that provides additional guidance on compliance.

Practical Implications for Aluminium Windows

In most Australian climate zones, thermally broken aluminium frames are now effectively required to meet NCC 2022 U-value limits — particularly for projects with large glazing areas. Non-thermally-broken aluminium double glazing typically achieves Uw values of 2.8–3.5 W/m²·K, which exceeds the DTS maximum in cool-temperate and mixed climates.

MC Windows & Doors’ thermally broken systems achieve Uw values of 1.2–1.6 W/m²·K, comfortably meeting DTS requirements in all eight NCC climate zones.

6. Compliance Pathways

NCC 2022 offers three compliance pathways for energy efficiency:

Pathway 1: NatHERS Assessment (Class 1)

The most common residential pathway. An accredited NatHERS assessor models the entire home using NatHERS-accredited software (e.g., FirstRate5, AccuRate, BERS Pro) and produces a certificate demonstrating 7-star compliance. Windows are modelled using their WERS U-value and SHGC data.

Pathway 2: Deemed-to-Satisfy (DTS) Provisions

A prescriptive pathway using the ABCB Glazing Calculator to verify that each elevation’s glazing meets the maximum U-value and SHGC limits. DTS is simpler than NatHERS but offers less flexibility — there are no trade-offs between building elements.

Pathway 3: Performance Solution

A custom compliance approach using engineering analysis, modelling, or comparison to a reference building. Performance Solutions offer maximum flexibility but require more documentation and are subject to stricter approval processes. The NCC Performance Solution Process Handbook (September 2024) provides guidance.

Mixed Pathways

Builders can combine pathways — for example, using DTS for glazing compliance and NatHERS for the overall building assessment. The chosen pathway must be documented in the construction certificate application.

7. Documentation Requirements

To demonstrate NCC 2022 energy efficiency compliance, builders should maintain:

WERS certificates for all window and door products, specifying the exact configuration being supplied
Glazing schedule listing each window’s U-value, SHGC, area, and orientation
Glazing calculator output (if using DTS) or NatHERS certificate
Installation details showing thermal break framing, insulation continuity, and sealing
Compliance documentation from the window manufacturer (test reports, AS 2047 certificates)

MC Windows & Doors provides comprehensive compliance documentation packs including WERS certificates, AS 2047 test reports, BASIX/NatHERS guidance, and installation details for all certified products.

8. Climate Zone-Specific Window Recommendations

Zone 4 (Mixed — Sydney, Perth)

Uw: ≤ 2.0 W/m²·K
SHGC: 0.30–0.40 (orientation-dependent)
Recommended: Thermally broken aluminium + double Low-E glazing + argon

Zone 5 (Mild Temperate — Melbourne, Adelaide)

Uw: ≤ 1.8 W/m²·K
SHGC: 0.35–0.45
Recommended: Thermally broken aluminium + double Low-E glazing + argon + warm-edge spacer

Zone 6 (Cool Temperate — Canberra, Ballarat)

Uw: ≤ 1.6 W/m²·K
SHGC: 0.40–0.55 (high, for passive solar heating)
Recommended: Thermally broken aluminium + double or triple Low-E + argon

Zone 7 (Alpine — Thredbo, Mount Hotham)

Uw: ≤ 1.4 W/m²·K
SHGC: 0.45–0.60
Recommended: Thermally broken aluminium + triple Low-E + argon + warm-edge spacer

Zone 2 (Hot Humid — Cairns, Darwin)

Uw: ≤ 2.5 W/m²·K
SHGC: ≤ 0.25
Recommended: Aluminium + Low-E double glazing with low-SHGC tinted glass

Frequently Asked Questions

1. What is Section J of the NCC?

Section J is the Energy Efficiency section of NCC Volume One, applicable to Class 2–9 buildings (apartments, commercial, public buildings). It covers building fabric (J4), external glazing (J3), building sealing (J5D3), and building services (J5–J8). For Class 1 residential buildings, the equivalent provisions are in Part 13 of the ABCB Housing Provisions Standard.

2. Do all windows need to meet NCC 2022 energy efficiency requirements?

Yes. All windows installed in new buildings, and most window replacements in existing buildings, must comply with NCC 2022 energy efficiency provisions. The specific U-value and SHGC requirements vary by climate zone, building type, and orientation. Compliance must be demonstrated through NatHERS assessment, DTS provisions, or a Performance Solution.

3. What U-value do I need for 7-star NatHERS?

There is no single U-value requirement — NatHERS compliance is assessed for the whole building. However, in most Australian climate zones, achieving 7-star NatHERS typically requires windows with whole-window U-values of 1.6–2.0 W/m²·K or lower. In cool-temperate and alpine zones, U-values of 1.2–1.6 W/m²·K may be necessary.

4. Can I use non-thermally-broken aluminium windows under NCC 2022?

Non-thermally-broken aluminium double-glazed windows typically achieve Uw values of 2.8–3.5 W/m²·K. In most Australian climate zones, this exceeds the DTS maximum U-value, particularly for projects with large glazing areas. Non-thermally-broken windows may be usable in hot climates (Zones 1–3) with small glazing areas, but thermally broken systems are increasingly the practical standard for NCC 2022 compliance.

5. Where can I download the NCC 2022 glazing calculator?

The ABCB provides free glazing calculators for NCC 2022 Volume One (Class 2 and 4) and Volume Two (Class 1) on the ABCB website at ncc.abcb.gov.au. The calculators are spreadsheet-based tools that simplify DTS compliance verification.

6. What is the Whole-of-Home framework?

The Whole-of-Home (WoH) framework, introduced in NCC 2022 for Class 1 buildings, is an annual energy budget approach that considers the combined energy consumption of the building envelope, heating and cooling systems, hot water, lighting, and renewable energy. It sets a maximum annual energy use budget that varies by climate zone, providing a more comprehensive assessment than the previous fabric-only approach.

Conclusion

NCC 2022 has fundamentally changed what the Australian building industry must deliver in window performance. The 7-star NatHERS requirement, the Whole-of-Home framework, and the new thermal bridging provisions collectively make thermally broken, high-performance glazing the new standard rather than an upgrade.

For builders, developers, and architects, the key to efficient compliance is specifying window systems that comfortably exceed the minimum DTS requirements — providing headroom for design flexibility and reducing the risk of non-compliance. MC Windows & Doors’ thermally broken aluminium systems achieve U-values as low as 1.2 W/m²·K, backed by 40+ international certifications, 19 AGWA WERS-rated energy systems, and comprehensive compliance documentation packs.

For NCC 2022 compliance support, WERS certificates, and project-specific window specifications, contact MC Windows & Doors at Annly@mcwindow.com.au or +61 490 141 931.

References

Australian Building Codes Board. (2022). National Construction Code 2022 — Volume One (Section J) and Volume Two (Part 13).
Australian Building Codes Board. NCC 2022 Volume One Glazing Calculator (Class 2 and 4). Available at: ncc.abcb.gov.au
Australian Building Codes Board. NCC 2022 Volume Two Glazing Calculator. Available at: ncc.abcb.gov.au
Australian Building Codes Board. NCC 2022 Whole-of-Home Calculator (beta release). Available at: ncc.abcb.gov.au
Australian Building Codes Board. (2023). A Review of Thermal Bridging Mitigation Provisions and Thermal Break Provisions NCC 2022.
Australian Building Codes Board. (2024). Housing Energy Efficiency Handbook and Commercial Energy Efficiency Handbook.
Standards Australia. (2014). AS 2047:2014 — Windows and external glazed doors in buildings.
Australian Glass and Window Association (AGWA). Window Energy Rating Scheme (WERS).
MC Windows & Doors. Compliance & Credentials. Available at: mcwindow.com.au