Queensland amendments to QDC MP4.1 – Sustainable Buildings

The Queensland Development Code (QDC) MP 4.1 (Version 1.16) has been updated. Queensland’s new approach to sustainable building:

• provides additional energy-efficiency compliance pathways for certain Class 1 homes. These include small homes, homes with raised floor construction and homes in Climate Zone 5.
• clarifies star rating credits that apply for outdoor living areas.
• updates ventilation requirements for Class 2 buildings as well as definitions, referenced standards and end-of-trip facilities.

What has changed?

The substantive change in MP 4.1 is for small homes (≤50 m²) and raised floor dwellings. It involves the introduction of additional thermal performance compliance pathways for Class 1 buildings. Version 1.16 now permits reduced NatHERS ratings - down to 4 stars in some instances. It also introduces a new DTS pathway for dwellings in Climate Zone 5. The remainder of the code is largely unchanged other than revised terminology, definitions and restructuring. These unchanged areas include water efficiency requirements, electricity sub-metering provisions and end-of-trip facility requirements.

Who is affected?

Builders, developers, certifiers, building designers, architects, energy assessors, and projects that were previously unviable or unable to comply when assessed against earlier provisions.

New pathways for Class 1a buildings

A Class 1 building and an attached enclosed Class 10a building must still comply with NCC H6P1 for thermal performance and H6P2 for energy usage. The proposed changes provide additional ways to demonstrate H6P1 compliance for these defined building types.

Small homes

A small home is a detached Class 1 building with a floor area (now defined in MP 4.1) of 50 m² or less. Acceptable solution A1(3) now allows:

• 5-star NatHERS rating; or
• 4.5-star NatHERS rating plus a 0.5-star outdoor living area credit obtained under A1(9)(a) of QDC MP4.1; or
• 4-star NatHERS rating plus a 1-star outdoor living area credit obtained under A1(9)(b) of QDC MP4.1. 

Raised floor construction 

Raised floor construction is a building form where at least 50% of the building’s total floor area is over an unenclosed space (defined in MP4.1). Acceptable solution A1(4) now allows:

• 6-star NatHERS rating;
• 5.5-star NatHERS rating plus a 0.5-star outdoor living area credit; or
• 5-star NatHERS rating plus a 1-star outdoor living area credit. 

For both the small home and raised-floor pathways, the total thermal energy load limit needs to be met, but the separate heating and cooling load limits do not apply.

Climate Zone 5 

A modification to the NCC elemental requirements for Class 1 buildings in Climate Zone 5 introduces an additional compliance pathway. This change addresses a longstanding issue whereby new dwellings with raised floors could only achieve compliance via a NatHERS assessment, while renovations could only be assessed against NCC 2019 requirements.

Acceptable Solution A1(5) modifies NCC Housing Provisions Table 13.2.6a, by replacing "X" with "reflective insulation facing down with a minimum R-Value of 2.5". The requirements of Parts 13.2 to 13.5 remain unchanged and must still be complied with, where applicable.

A building is not required to satisfy the definition of raised floor construction to use the A1 (5) pathway. The pathway may be used where any part of the floor is over an unenclosed space, including where less than 50% of the total floor area is over an unenclosed space.

Changes to outdoor living area definition

The definition of an outdoor living area has been amended to more closely align with NCC 2022 S42C2. While the requirements for minimum area, dimensions, roof coverage and openness remain largely unchanged from Version 1.15, Version 1.16 introduces a minimum 900 mm clearance between the qualifying open sides of the outdoor living area and any allotment boundary or obstruction to the breeze path. The principal remaining difference is that the QDC does not mention the minimum 2.1 metre opening height specified by NCC 2022 S42C2.

Class 2 buildings are largely unchanged under Version 1.16. The principal amendments are the introduction of the new outdoor living area definition, including the 900 mm breeze-path clearance requirement, and recognition of the floor of an outdoor living area immediately above as an acceptable form of roof covering for the purposes of claiming outdoor living area credits.

Industry considerations

The introduction of the 900 mm clearance requirement may affect whether some patios, balconies and verandahs qualify as an outdoor living area under Version 1.16. A roofed patio or balcony design that may have qualified under Version 1.15 may no longer be eligible where a boundary fence, neighbouring building or other obstruction is located too close to a qualifying open side. Outdoor living areas lawfully approved under Version 1.15 remain compliant.

No minimum opening height is prescribed for an outdoor living area. Consequently, elevated balconies, decks and verandahs that require balustrades may still satisfy the definition where the relevant side remains open above the balustrade and the required 900 mm clearance to any boundary or breeze-path obstruction is maintained. For example, a solid balustrade or block wall approximately 1 metre high does not automatically prevent a side from being considered open under the current wording. Practitioners should nevertheless consider whether the overall design continues to achieve the natural ventilation outcome intended by the provision.

A minimum floor area of 12 m² and a minimum dimension of 2.5 metres in all directions is required for an outdoor living area. However, the provisions do not expressly address how larger or irregularly shaped outdoor living areas should be assessed where only part of the area satisfies these qualifying criteria. For example, a 30 m² balcony may contain a 12 m² area that satisfies the dimensional and opening requirements, together with narrow sections that would not independently qualify. In these circumstances, it is unclear whether fan coverage should be assessed against the entire balcony or only the qualifying outdoor living area. A reasonable interpretation is that the portion satisfying the outdoor living area definition is the relevant area for determining eligibility for the nominal credit.

Other technical and administrative changes

Flood exclusion for raising an existing building

The wording of the exclusion is clarified for existing Class 1 buildings where one of the three flood or storm-surge triggers apply. The building certifier must also certify that the work is, or directly relates to, raising the existing building.

Bicycle definition

The definition is expanded to include a bicycle with an auxiliary motor, provided its total power output is not more than 250 watts.

Designated local government area 

For a local government not listed in the schedule, publication of a designation changes from newspaper and website to newspaper or website.

Floor area

New definitions are introduced that affect the small-home and raised-floor tests. A Class 1 floor-area definition is the gross area of all floors in the building measured over the enclosing walls other than the area of a verandah, roofed terrace, patio, garage or carport in or attached to the building. For an outdoor living area, this is measured over its finished floor surface.

Metering standards

AS 62053.21 and AS 1284.1 are no longer tied to the 2005 and 2004 editions in the referenced-standards table. The draft generally refers to the most recent edition unless otherwise stated.

End-of-trip facilities

The requirements are renumbered to P7/A7. Schedule 5 also presents separate female and male change-room rows for developments providing 6 to 19 bicycle spaces.

New climate-zone schedule

A new Schedule 1 provides Queensland climate-zone information. Existing schedules are consequently renumbered.

What builders, designers and certifiers should do 

• Confirm the version of QDC MP 4.1 that applies to the building development application.
• At concept design, identify whether the project may qualify as a small home, raised floor construction or within Climate Zone 5.
• Nominate the QDC version on approval documentation.
• Update standard specifications, design checklists, energy assessment briefs and certifier submission templates.

Version 1.16 is intended to give industry more flexibility for selected Queensland homes. However, the concessions depend on precise definitions and evidence. Members should ensure before claiming a lower-rating pathway or outdoor living area credit that the building, floor area, underfloor space and breeze-path conditions satisfy the new wording.

To find out more, contact HIA's Building Services team.

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The above is intended to provide general information in summary form. The content does not constitute specific advice and should not be relied upon as such. Formal advice should be sought by members and customers with respect to particular matters before taking action.