Residential Glazing and Solar Design
Glazing and shading decisions influence more than the appearance of a home. They shape how solar heat enters, how heat escapes and how the building responds to seasonal conditions.
Under Verification Using a Reference Building, or VURB, these design characteristics contribute to the thermal comparison between a proposed dwelling and a compliant reference building. Understanding how they affect the model can help architects and project teams make more informed decisions before glazing and external shading specifications are finalised.
In Brief
Under the national NCC 2022 H6V2 method, the proposed dwelling and reference building must share prescribed characteristics, including orientation, floor plan and the location and size of glazing.
The reference building uses the relevant compliant glazing and construction assumptions, while the proposed building is assessed using its intended specifications, subject to the Verification Method.
Window U-values, solar heat gain coefficients, shading arrangements and the surrounding building fabric can influence the calculated heating and cooling loads.
However, improved glazing or shading does not guarantee compliance. The proposed dwelling must satisfy the applicable reference building comparison and all retained direct requirements.
Confirm the Jurisdiction First
This article discusses the national H6V2 Verification Method under NCC 2022 Volume Two. Its availability depends on the applicable NCC edition, jurisdictional variations and project circumstances.
H6V2 does not apply in New South Wales under the NSW variation to NCC 2022. See Where Can VURB Be Used in Australia? for the jurisdictional context.
Thermal Performance
Windows influence residential thermal performance through two important mechanisms: heat transfer through the glazing system and solar radiation entering the dwelling.
Heat transfer can contribute to winter heat loss or unwanted heat gain when indoor and outdoor temperatures differ. Solar radiation passing through glazing can provide useful warmth in cooler conditions but may also increase cooling demand during warmer periods.
The result depends on the glazing system, orientation, window area, external shading, surrounding building form and climate. The same window specification may perform differently when installed on different elevations.
For this reason, glazing performance should be considered as part of the overall building design rather than selected solely by glass type or appearance.
Glazing Specifications
01 — Heat Transfer
The U-value describes the rate of heat transfer through the complete window system. A lower U-value generally indicates reduced conductive heat transfer through the glass and frame assembly.
02 — Solar Gain
SHGC describes the proportion of incident solar energy admitted through the glazing system. Lower values generally reduce solar heat gain, although this may also reduce beneficial winter gains.
03 — Solar Exposure
The direction a window faces and the shading it receives influence when solar radiation reaches the glazing and how that exposure affects seasonal heating and cooling demand.
Window specifications should use appropriate whole-system performance information rather than assuming that centre-of-glass values represent the installed window assembly. The relevant glass, frame and shading characteristics must be represented consistently in the assessment.
Reference Building Rules
One of the most important aspects of H6V2 is that the proposed and reference buildings use the same floor plan, including the location and size of glazing.
The reference building is therefore not a smaller, simpler dwelling with fewer windows. It retains the prescribed geometry of the actual design while applying the relevant compliant construction and glazing assumptions.
This allows the proposed glazing specifications to be assessed against the reference building's compliant assumptions without changing the window area or orientation between the two models.
Changing the size or position of a window is a change to the proposed design itself. It may require both models to be updated so that the comparison continues to reflect the same prescribed building geometry.
Orientation and Seasonal Exposure
Window orientation influences the timing and intensity of solar exposure. In Australian conditions, north-facing glazing can provide opportunities for winter solar access, while east- and west-facing windows can receive lower-angle sunlight that may be more difficult to shade.
These relationships are not universal performance guarantees. Local climate, neighbouring structures, roof projections, window properties and the building's thermal characteristics all influence the outcome.
Under H6V2, orientation is a prescribed common input for the proposed and reference buildings. The assessment cannot improve the comparison by modelling the reference building at a less favourable orientation than the actual dwelling.
Where orientation is being reconsidered during design, the project team should understand that a revised orientation changes the underlying project conditions and requires an appropriately updated comparison.
External Solar Control
External shading can reduce the amount of direct solar radiation reaching glazing, potentially reducing cooling demand during periods of high solar exposure.
Common architectural responses include eaves, verandahs, balconies, fixed canopies, shading hoods, external screens and adjustable shading devices.
Their effect depends on projection depth, window position, orientation, solar angle, surrounding obstructions and the way the device is represented in the model.
Shading is not automatically beneficial in every season. A projection that reduces summer solar gains may also reduce useful winter gains, potentially increasing heating demand.
H6V2 requires the calculation method to account for glazing and shading. Any proposed shading benefit must be supported by the actual design, appropriate modelling assumptions and the requirements of the selected verification method.
Design Response
| Design decision | Potential thermal influence | VURB consideration |
|---|---|---|
| Lower window U-value | Can reduce heat transfer through glazing | Model the proposed whole-window performance against the compliant reference assumptions |
| Lower SHGC | Can reduce solar gains and cooling demand, but may also reduce useful winter gains | Assess both relevant seasonal load effects |
| Deeper external overhang | Can reduce direct solar exposure during particular periods | Represent the actual shading geometry and applicable reference assumptions accurately |
| External shading screen | Can reduce incident solar radiation depending on geometry and operation | Use supportable device properties and operating assumptions |
| Changing window dimensions | Changes the balance of solar gain, heat transfer and building geometry | Update both models to retain the prescribed common glazing size and location |
| Changing orientation | Changes solar exposure across the dwelling | Reassess the proposed and reference buildings using the same revised orientation |
These are general design influences, not predicted compliance outcomes. The effect of a particular change must be determined through the applicable modelling method and project conditions.
Performance Boundaries
No. VURB should not be understood as an unrestricted trade-off method through which improved glazing can compensate for any construction deficiency.
The proposed building must satisfy the applicable heating and cooling load comparisons. In NCC climate zones 2 to 7, the national H6V2 method requires both loads to be no greater than the corresponding reference building values.
Specified requirements relating to thermal insulation, thermal breaks, floor edge insulation and building sealing also remain directly applicable under H6V2.
Improving a window specification may help the thermal comparison, but it cannot remove these retained obligations or guarantee an acceptable overall result.
Early Design Coordination
Glazing and shading are most useful to review while the design still has room for adjustment.
At concept or developed design stage, architects may still be able to refine window specifications, coordinate overhangs, resolve external shading devices and evaluate the thermal consequences of design decisions.
Later changes can affect elevations, structural coordination, procurement, window schedules and assessment documentation.
An early compliance pathway review can identify whether VURB is legally available and whether comparative modelling would be proportionate. Design changes should then be evaluated against the actual requirements of that pathway rather than assumed to produce a favourable result.
Glazing and Shading Inputs
An informed technical review requires sufficient information to represent the proposed glazing and surrounding solar conditions accurately.
Preliminary information may support an early review, while formal modelling requires coordinated and sufficiently defined inputs. For the wider submission requirements, see VURB Assessment Documents: A Residential Submission Checklist.
Frequently Asked Questions
VURB uses a comparative thermal performance method where it is available. It does not automatically permit larger windows. The proposed and reference buildings use the same prescribed glazing size and location, and the proposed building must satisfy the applicable heating and cooling criteria.
Can a lower SHGC improve a VURB result?Potentially. A lower SHGC can reduce solar heat gain and may reduce cooling demand. It can also reduce beneficial winter gains, so the overall effect depends on climate, orientation, shading and the required load comparisons.
Is double glazing always sufficient for VURB compliance?No. Double glazing describes a construction arrangement, not a guaranteed thermal performance outcome. Whole-window U-value, SHGC, frame properties, orientation, shading and the broader building envelope must be considered.
Can external shading reduce the cooling load?Yes, external shading can reduce solar radiation reaching glazing and may reduce cooling demand. Its effectiveness depends on the actual geometry, orientation, climate and modelling assumptions. Any effect on winter heating demand should also be considered.
Can the reference building have smaller windows than the proposed dwelling?No. Under national NCC 2022 H6V2, the proposed and reference buildings must use the same floor plan, including the location and size of glazing. The reference building applies the relevant compliant performance assumptions to that prescribed geometry.
Does adding shading guarantee a passing VURB assessment?No. Shading can influence the heating and cooling loads, but the proposed building must still satisfy the relevant comparison criteria and all retained direct requirements. The effect must be demonstrated through appropriate modelling.
Is H6V2 available for residential projects in NSW?H6V2 does not apply under the NSW variation to NCC 2022 Volume Two. NSW projects must be assessed against the applicable BASIX, NSW NCC and approval requirements.
Related Guidance
Knowledge Hub
Explore the method, technical framework and broader assessment considerations.
Thermal Modelling
Understand reference building calculations, climate-zone criteria and model limitations.
Design Complexity
Explore the broader role of geometry, construction and design complexity in pathway selection.
Jurisdictional Requirements
Review NCC editions, state variations and jurisdiction-specific availability.
Residential Design and Compliance Review
Share your project location, architectural drawings, glazing specifications and proposed shading details. Certified Energy can review the applicable residential energy efficiency requirements and advise whether a reference building assessment or another compliance pathway is appropriate.
Explore VURB Assessment ServicesLast reviewed: October 2026. This article discusses the national H6V2 method under NCC 2022 Volume Two. Applicable NCC editions, jurisdictional variations and project-specific approval requirements must be confirmed. Part of the Certified Energy Residential Compliance Knowledge Hub.