Complex residential designs can create energy compliance challenges that are not always resolved efficiently through a standard assessment pathway. Extensive glazing, unusual geometry, large internal volumes, multiple orientations and non-standard construction systems can all affect how a dwelling performs against the applicable NCC requirements.
Verification Using a Reference Building, commonly known as VURB, may be worth investigating where the design cannot be assessed appropriately through a straightforward Deemed-to-Satisfy or NatHERS pathway. It is not automatically required for complex homes, and it does not provide unrestricted design flexibility. Its suitability depends on the dwelling, jurisdiction, applicable NCC provisions and proposed compliance strategy.
In Brief
VURB may be considered where a residential project needs a comparative performance-based assessment against a compliant reference building. It can be particularly relevant where glazing, geometry, orientation, shading or envelope construction make direct compliance difficult to demonstrate without significant changes to the design.
The pathway does not replace every applicable NCC requirement. Certain provisions may continue to apply directly, and the proposed dwelling must still be supported by suitable modelling inputs, construction information and technical evidence.
Before commissioning an assessment, the project team should confirm that the pathway is available in the relevant state or territory and appropriate for the building classification and approval process.
Jurisdiction Note — New South Wales
H6V2 Verification Using a Reference Building does not apply in New South Wales under the NSW variation to NCC 2022 Volume Two. NSW residential projects must instead be reviewed against the applicable BASIX, NSW NCC and approval requirements.
This limitation is specific to New South Wales. Pathway availability in other jurisdictions depends on the locally adopted NCC provisions and relevant approval requirements.
Design Complexity
Architectural complexity is not determined only by the size or value of a home. A relatively small dwelling may require careful assessment where its form, glazing or construction systems create unusual thermal conditions. Conversely, a larger dwelling with simple geometry and coordinated documentation may be comparatively straightforward to assess.
From an energy compliance perspective, complexity often arises where several design factors interact. A glazing decision may affect solar gain, heat loss, shading and the performance of surrounding building elements. A change to roof geometry may alter internal volumes, exposed surface area and insulation continuity. Non-standard wall or floor systems may require additional information before their thermal properties can be modelled reliably.
The relevant question is therefore not simply whether the home is architecturally ambitious. It is whether the proposed design can be assessed clearly and compliantly through the available residential energy pathway.
Complex Design Factors
Large glazed areas can significantly influence residential thermal performance, particularly where windows face multiple orientations or include different frame, glass and shading specifications.
Complex glazing schedules can require close coordination between architectural drawings, window schedules and modelling inputs. The effect of glazing cannot be considered in isolation; orientation, external shading, frame performance and the surrounding envelope all influence the final assessment.
Split levels, double-height spaces, curved or articulated forms, complex rooflines and irregular floor plans can increase the work required to define the proposed dwelling accurately.
These design conditions may also create differences in exposed surface area, zoning, solar access and heat transfer that are not apparent from floor area alone. Clear plans, elevations and sections are particularly important where the geometry is not conventional.
Homes with wings, courtyards, angled façades or glazing facing several directions can experience substantially different solar conditions across the building.
External screens, deep reveals, verandahs, pergolas, balconies and neighbouring obstructions may also affect performance. These elements need to be documented consistently so they can be represented appropriately in the assessment.
Complex homes may use unusual wall, roof or floor assemblies, mixed construction systems or architectural details that are not fully described by generic material assumptions.
A VURB pathway does not automatically validate an innovative product or construction system. The assessor still needs reliable information about layer composition, insulation, thermal bridging and relevant thermal properties. Separate product evidence or certification may also be required outside the energy assessment scope.
Some projects reach energy assessment after important architectural decisions have already been made. Planning controls, views, bushfire requirements, heritage considerations, site constraints or client priorities may limit the ability to alter glazing, orientation, roof form or external appearance.
Where direct compliance would otherwise require significant redesign, a reference-building pathway may be worth examining. This does not mean the original design will necessarily comply unchanged. Modelling may still identify areas where glazing, shading, insulation or construction details need to be revised.
Pathway Boundaries
VURB compares the proposed dwelling with a compliant reference building using the applicable verification method. This can provide an alternative way to demonstrate the required residential energy efficiency outcome where the pathway is legally available and technically suitable.
It can allow the dwelling to be considered as a coordinated design rather than treating every element as an isolated prescriptive requirement. The relative performance of glazing, shading, orientation, form and building fabric can therefore be examined together within the defined comparison.
However, VURB should not be presented as a mechanism for avoiding the NCC or removing all design constraints. It does not guarantee that extensive glazing, low-performing materials or incomplete construction details will be accepted. The proposed building must still satisfy the relevant verification criteria and any NCC provisions that continue to apply directly.
VURB also does not measure actual household energy bills, occupant behaviour or future operational energy consumption. Those questions sit outside the core residential reference-building compliance comparison.
Pathway Selection
A complex architectural design does not automatically require VURB. Many carefully designed homes can still demonstrate compliance through NatHERS or the applicable Deemed-to-Satisfy provisions.
NatHERS assesses residential thermal performance through accredited software and provides a star rating and heating and cooling load results. DTS follows the applicable prescriptive NCC provisions. VURB uses a comparison between the proposed dwelling and a compliant reference building.
The appropriate pathway depends on the project location, building classification, design, documentation and approval context. It should be selected on technical and jurisdictional grounds rather than on the assumption that one pathway is universally more flexible or more favourable.
For a more detailed comparison, see VURB vs DTS: When Does a Reference Building Pathway Make Sense?
Early Review
The earlier the compliance pathway is reviewed, the easier it is to identify whether the design can proceed through NatHERS or DTS or whether a reference-building pathway should be investigated.
Early review can reveal which elements are likely to influence the assessment most strongly. For a complex dwelling, these may include glazing areas, frame and glass selections, external shading, roof form, exposed floors, insulation continuity or the interaction between different construction systems.
This allows the design team to make targeted decisions before architectural documentation, consultant coordination and product selections become difficult to change. It can also prevent time being spent developing a VURB strategy in a jurisdiction where H6V2 is not available.
Early review does not require every construction detail to be finalised. Concept plans, elevations, sections and an initial understanding of the envelope may be sufficient for a preliminary pathway discussion.
Project Information
An initial review should provide enough information to understand the location, classification, scale and complexity of the proposed dwelling. Common project information includes:
Incomplete early-stage information does not necessarily prevent a preliminary review, but assumptions and unresolved details should be identified clearly. For a more detailed submission checklist, see VURB Assessment Documents: A Residential Submission Checklist.
Assessment Outcomes
VURB may provide a more suitable way to assess a complex design, but it does not guarantee that every original design decision can be retained.
The comparative modelling may show that the proposed dwelling requires changes to glazing, shading, insulation, thermal bridging details or other envelope elements. The purpose of the assessment is to demonstrate the required compliance outcome, not to justify a predetermined design regardless of performance.
The benefit of a coordinated assessment is that changes can be considered strategically. Rather than assuming that every element must be upgraded independently, the project team can understand which parts of the design have the greatest influence on the comparison.
Assessment Cost
Complex dwellings can require more modelling, documentation review and coordination than conventional designs. The assessment fee may be influenced by geometry, glazing, shading, construction systems, documentation quality, reporting requirements and the number of design iterations required.
Floor area is only one consideration. A smaller home with irregular geometry and an unresolved glazing schedule may require more work than a larger dwelling with a simple form and coordinated documentation.
For a detailed explanation of scope and pricing factors, see How Much Does a VURB Assessment Cost in Australia?
Frequently Asked Questions
No. Architectural complexity alone does not determine the compliance pathway. Many complex homes can still be assessed through NatHERS or the applicable DTS provisions. VURB should be investigated only where it is available and technically appropriate for the project.
VURB and NatHERS are different assessment pathways. VURB uses a proposed-versus-reference-building comparison, while NatHERS assesses thermal performance through accredited software and produces a star rating and load results. Whether one pathway is more appropriate depends on the project and jurisdiction.
No. Extensive glazing still affects heating and cooling performance and must be represented accurately in the modelling. A VURB assessment does not guarantee that a glazing design will comply without changes to the glass, frames, shading or surrounding building fabric.
Not by itself. The assessment requires reliable thermal properties and construction information, but separate evidence may be needed to demonstrate that a product or system satisfies other applicable NCC requirements.
No. H6V2 Verification Using a Reference Building does not apply under the NSW variation to NCC 2022 Volume Two. NSW residential projects must instead be reviewed against the applicable BASIX, NSW NCC and approval requirements.
The pathway should ideally be reviewed during concept or design development, before major glazing, geometry and construction decisions are locked into the documentation.
VURB is a residential reference-building compliance comparison. It should not be presented as an assessment of actual household energy bills, occupant behaviour or the full operational performance of building services.
Related Knowledge
Knowledge Hub
Understand the residential reference-building method, pathway availability and assessment process.
Pathway Comparison
Compare direct residential DTS compliance with a reference-building Performance Solution pathway.
Project Preparation
Review the plans, schedules and construction information commonly needed for an assessment.
Residential Pathway Review
Send the project location, current drawings, glazing information, construction details and approval requirements. Certified Energy can review whether VURB appears available and appropriate before confirming the assessment scope.
Send Your Project for ReviewLast reviewed: June 2026. This article forms part of the Certified Energy Residential Compliance Knowledge Hub.