How are alterations and additions assessed in Queensland?
The Queensland Government’s Modern Homes Standards – Home Renovation Guideline, published in August 2026, provides some much-needed clarity around energy-efficiency requirements for alterations and additions.
For NatHERS assessors, building designers and building certifiers, the biggest change is the introduction of a clearer 50% volume rule and a new methodology for assessing renovations using NatHERS software.
The 50% rule
Where the renovation is less than 50% of the existing home’s volume, the new work must comply with current Energy Efficiency requirements. However, under Section 61 of the Building Act, the certifier may approve the work using the provisions under which the existing building was assessed (or any other previous Energy Efficiency provisions they deem suitable e.g. BCA 2009 regulations for a building built in 1950)
Where the renovation is more than 50% of the existing home’s volume, the new work must comply with current Energy Efficiency requirements, with no equivalent discretion to exempt it. Under Section 81, the certifier may also require all or part of the existing dwelling to comply with current standards.
Two Assessment Methods
Whether greater than or less than 50%, the renovations can be assessed for Energy Efficiency compliance using either Deemed to Satisfy Elemental (DTSE) or NatHERS.
Method 1: Deemed to Satisfy Elemental (DTSE)
DTSE is most commonly used for smaller additions, but can be applied to major renovations or new builds as well. In Queensland the options are:
- DTSE via NCC 2022 provisions
- DTSE via NCC 2019 provisions – only if the dwelling has a qualifying outdoor living area with qualifying ceiling fans
- DTSE via earlier NCC versions if Certifier uses their discretion with <50% volume renovatios.
Method 2: NatHERS – a new approach
The new guidance provides a more structured approach to using NatHERS for renovations.
Rather than simply treating the project as a new 7-Star dwelling, the methodology considers the existing home’s performance and the proportion of new work.
The New NatHERS Process
For those who like the detail, here’s the process for Method 2 – the new NatHERS approach:
1. Model the existing dwelling
The existing home is modelled in NatHERS to establish its current star rating.
2. Calculate the Required Star Rating (Rsr)
The Modern Homes Standard Renovation Guide includes a formula for calculating the Required Star Rating for the renovated dwelling.
It uses the volume of the existing dwelling, the volume of the new/altered work, the star rating of the existing dwelling and the applicable minimum rating to calculate the Required Star Rating for the renovated dwelling. The applicable minimum rating is usually 7.0 Stars, but per the Queensland Development Code MP 4.1 issued on 14th August, 2026, this Star Rating can be reduced to 6.0 Stars for raised floor dwellings or 5.0 Stars for small homes (<50m2 floor area).
3. Model the proposed renovation
The proposed dwelling is then modelled to achieve the calculated Required Star Rating.
This is a significant shift from the commonly used approach of rating the whole dwelling to 7 Stars and then applying requirements only to the new work.
The new methodology recognises that the existing building already has a level of thermal performance — and that should form part of the compliance calculation.
4. Produce Energy Report
The Energy Report is then sent to the client along with
- The draft NatHERS certificate for the existing dwelling; and
- The NatHERS certificate for the proposed renovation, used for plan stamping.
- The calculation workings of the Required Star Rating.
5. Stamp Plans and Produce Form 15.
When the construction plans are updated with the Energy Efficiency requirements, they can be stamped with the appropriate NatHERS Stamp and returned to the client with the Form 15.
Whole of Home
Whole of Home requirements also need to be considered.
For smaller renovations, the assessment is generally unlikely to extend to appliances unless major systems such as air-conditioning, hot water or pool equipment are being changed.
For larger renovations, however, a Whole of Home assessment is usually required.
The practical takeaway
The new renovation methodology is a positive step towards a more proportionate approach to existing homes. It also provides clarity and accuracy when assessing a renovation for Energy Efficiency.