Note: This information is correct at time of publication (February 2023), but will change in Oct 2023 when new legislation is adopted
New homes are mostly assessed in Queensland via the NatHERS Star Rating method, or via the Deemed to Satisfy – Elemental Provisions (DTS) method. (And occasionally via the Performance Solution method). See here (https://www.bera.com.au/2015/11/24/deemed-to-satisfy-vs-nathers-star-ratings/) for a discussion comparing these two methods.
But what about additions and alterations? Does a minor renovation need an energy efficiency assessment? How minor is minor? What’s the trigger? Who decides? Is Queensland different to other states/territories in this regard? How much of the alteration needs to be assessed? What about the existing building? So many questions. Read on, my friends!
Is Queensland different to other states/territories in this regard?
Yes! The National Construction Code (NCC) is the governing legislation for Energy Efficiency Assessments in Australia, but it is adopted with variations by each State and Territory. And the variations are quite pronounced when it comes to adds & alts.
What is the relevant legislation in Queensland?
Queensland has two relevant pieces of legislation that work together to adopt the requirements of the NCC:
- The Building Act (1975),
- The Queensland Development Code MP 4.1 – Sustainable Buildings (QDC MP4.1)
The Building Act (1975) provides for the QDC, and is the overall governing legislation for building and building approvals in Qld.
The QDC MP4.1 provides oversight in the specific area of Sustainable Buildings and the energy efficiency legislation.
What are the rules for Queensland?
If the renovations are internal only, and no building development approval is required, then no Energy Efficiency Assessment is required.
If a DA or BA is required, this is where things get interesting! The Building Act and the QDC don’t appear to line up on the assessment of alterations and additions, and so care needs to be taken to ensure compliance.
Rules for a “Major Renovation”
If a DA or BA is required, and if the current renovation (including any structural alterations carried out in the previous three years) represents more than half the total volume of the existing building, there is a specific section of The Building Act – S 81 (Building development approval for particular alterations may require existing building or structure to comply with building assessment provisions) that applies.
This section states that if the 50% is exceeded (or if the Certifier deems the alterations pose a risk to safety or fire safety), then:
“The building development approval may include a condition that all, or a stated part, of the existing building or structure, must comply with all or a stated part of the building assessment provisions as if it were a new building or structure”.
So, for a major renovation, the Certifier decides whether the Energy Efficiency requirements need to apply to the whole building or just the additions and alterations, per S81.
The ‘more than half the total volume’ is not explained further. So there is discretion on that point as well. For example, if the flooring in the whole house is being re-done, and 2 windows swapped from sliding to louvre, is that more than 50% by volume of the dwelling being altered? What about if all the walls and ceilings are being re-lined? What if there is a pure addition of 3 rooms, but they only comprise an additional 40% by volume?
The QDC Guide, although not binding, interprets the QDC and provides guidance for its implementation. It states that “Building certifiers should take into account the factors associated with requiring compliance when compared to the potential benefits. For example, if the building work represents more than 50 per cent of the existing building’s floor area, the building certifier can impose conditions in the approval that require the existing part of the building to comply with all or a stated part of the current building assessment provisions. The building certifier may reasonably decide not to impose conditions for upgrading the existing part of the building in circumstances where they consider that applying the new building requirements would:
not provide a level of benefit commensurate with, or exceeding, the additional
costs
otherwise be overly onerous or technically impractical” (4.3.2, QDC Guide)
Therefore, the Energy Assessor needs to obtain direction as to the scope of their Assessment in a particular renovation from the building certifier. This adds to the time and expense required to undertake an Energy Assessment, especially if the Certifier takes time to reply to a request for guidance as to scope. However, there is a general practice that is followed 99% of the time (see below).
Rules for a “Minor Renovation”
If the current renovation (including any structural alterations carried out in the previous three years) represents less than half the total volume of the existing building, there is no provision in The Building Act. One might conclude that an assessment is not required. However, this does not mean that there is no requirement for assessment, as alterations are also covered under the QDC MP4.1.
QDC MP4.1 says that the following Performance requirements apply to additions and alterations:
- P1 – Energy Efficiency,
- P3 – Lighting and
- P5 – Hot water System
(Note these are the same requirements that apply to new dwellings, except for Water Conservation requirements, which only apply to new dwellings).
So even minor additions (requiring a BA or DA) need an Energy Efficiency Assessment, but only on the parts of the building that are being altered or added to by the renovation.
The QDC MP4.1 Guide discusses alterations (which include additions) and provides for a common sense approach, saying that the alterations need to comply “as much as practical.” (4.3.2, QDC Guide)
Therefore a DTS Assessment on the alterations is the most straightforward approach, as it can be clearly demonstrated what parts of the work the energy assessment relates to.
When discussing using the NatHERS Software to assess an alteration, the QDC Guide has some interesting suggestions.
The first seems at odds with the NatHERS Tech Note’s specific requirement to only use the NatHERS Software to assess a whole dwelling (“NatHERS software tools are used to assess an entire dwelling. Additions or extension to an existing dwelling must be modelled as part of the entire dwelling”, NatHERS Tech Note, June 2019, part 2.3). The QDC Guide states “To determine the energy equivalence rating for an alteration to an existing house, a software assessment of the building design is recommended. The plans need to include the kitchen area as a reference point to undertake the software assessment to determine internal heat loads. The software assessment could model the area covered by the alteration (inclusive of the kitchen area). Accredited NatHERS Assessors (and they should all be accredited!), cannot follow the QDC Guide at this point, as they need to model the whole dwelling.
The QDC Guide goes on to state: “Another approach is to undertake two assessments of the entire house, one before and one after the alteration, to demonstrate any degree of energy efficiency improvement. The building certifier should consider any of the available practical steps that the energy efficiency assessor has identified that could assist the house in achieving a rating as close to 6 stars as possible. It is recommended that homeowners discuss possible requirements involved with the alteration with the building certifier as early as possible in the design stage.
Where practical, the following features should be considered and applied to the alteration:
insulation in new walls, roof lining and ceiling (note, for some councils, a change in roof type, for example, from tile to metal sheet roofing, is subject to a building development application)
shading of walls and windows with roof eaves and awnings (note, it would not be expected that existing roof eaves would need to be altered)
window size, type and location to promote cross-ventilation
lighter colour roof and external walls
treated glazing
ceiling fans in living areas and bedrooms.”
This guidance implies that a NatHERS Assessment can be undertaken but then allow common sense to apply as to which features should be required to be implemented. Given the sophisticated science behind all the inputs in a NatHERS Assessment, it seems like a strange approach to have a model which shows 6 Star compliance, but then the building certifier decides which of the inputs should be adopted. Note this is guidance that most NatHERS Assessors would not recommend be followed by the Building Certifier, as NatHERS Assessors have far more training, practice and skill in determining which features will contribute to thermal comfort and energy efficiency.
What about having the additions assessed under older legislation?
S61 of The Building Act states that “Alterations to safe existing work may be approved on the basis of earlier building assessment provisions”. It would be possible to make a case to a building certifier that a particular alteration would be best assessed via earlier legislation, but it would be the certifier who would have the final say. An example might be an older home with single-glazed windows throughout that is having 2 windows replaced as part of a renovation. If those windows had to be consistent with current energy efficiency legislation, they might need to be low-e or double-glazed, but this would have them looking different to the existing windows beside them. One solution would be to have all the windows replaced, but this would be overly costly and impractical. In this case, the building certifier could allow for the new glazing to be assessed via earlier legislation, which would allow for consistent single glazing throughout.
What is the practice in Queensland?
So, the guidance for alterations and additions is not actually straightforward or consistent. What happens on the ground?
If there is a BA or DA for a renovation, there should be an Energy Efficiency Assessment carried out.
Most building certifiers require an Energy Efficiency Assessment in the following three cases:
- where there is significant new work being added to an existing building
- where there are new windows being added
- where there is a change of use from non-habitable to habitable (think Garage conversion to bedroom).
In these cases, the new work is assessed, usually via the DTS Method, and needs to comply with current Energy Efficiency Legislation. If the new windows are only facing a particular direction, it is considered reasonable for the Assessor to assess the glazing of the floor as a whole but only require the new glazing to comply with the requirements. This practice is not referenced in any Queensland-specific legislation but is the guidance noted and explained in the Victoria Building Authority’s Practice Note 55-2018 “Residential Sustainability Measures.”
This is the common sense, practical approach in 99% of cases.
Can you get a NatHERS Assessment on an addition or alteration?
Yes, you can, and this is provided for in the QDC MP 4.1 for alterations. A NatHERS Assessment of the whole (renovated) dwelling is the best way of determining the thermal performance of the renovated dwelling. It can be difficult to get the whole dwelling to achieve 6 Stars in certain situations, such as an older house with no wall insulation being added. However, there is provision in the QDC Guide for the rating to only be “as close to 6 Stars as possible”, so the NatHERS Assessor can work with the Certifier to determine the best way forward in these situations.
A NatHERS assessment will give a good picture as to the thermal performance of the dwelling as a whole and show the client where the home is performing well and where additional measures could be implemented. The requirements of the NatHERS Assessment for the existing parts of the dwelling only need to be included in construction ‘where practical’ (per QDC Guide).
Can you summarise all this for me?
- Internal Renovation not requiring building approval – no energy efficiency assessment is required
- Minor Renovation (less than 50% by volume of dwelling altered) – energy efficiency assessment on new or altered works only, usually via DTS, but NatHERS can be used if preferred.
- Major Renovation (more than 50% altered) – certifier decides scope of energy efficiency assessment, ranging from new only, to whole dwelling. This can be carried out via DTS or NatHERS.
What is BERA’s approach?
As always, at BERA we are focused on working within the legislation to give our customers a result that suits their priorities for their renovation.
- If thermal comfort and energy efficiency savings are a priority, we will assess your renovation and show you how to achieve this, usually via a NatHERS Assessment.
- If straightforward compliance at a straightforward price is the aim, we can do that as well (often via a DTS Assessment).
- If there is a particular feature that you really want, such as single glazing or a dark roof or no ceiling fan on your outdoor living area, we do all we can within the legislation to enable your build to proceed in that direction.
Contact us at BERA for a free quote.