Short answer
JV3 is assessed by creating two energy models: one of a reference building built to DtS rules, and the other of the proposed design. The annual energy consumption of the proposed design must not exceed that of the reference building. Weather, orientation, glazing, building fabric, occupancy, lighting, HVAC and thermal comfort are all part of the comparison.
Full answer
The JV3 assessment process involves detailed modelling of two building versions. The Reference Model is constructed to strictly comply with the Deemed-to-Satisfy (DtS) Section J provisions, incorporating standard insulation, glazing U-values, roof, wall and floor fabric, as well as services. The Proposed Model reflects the actual design choices you intend to apply, which may include higher glazing ratios, different insulation levels, and improved service efficiencies. Both models undergo simulation using advanced thermal modelling software such as DesignBuilder or IES, taking into account site location, orientation, climate data, external heat loads, shading, occupancy schedules and lighting. The key comparison is that the proposed design’s energy consumption, measured in megajoules or kilowatt-hours per square metre annually, must not exceed that of the reference building. Additionally, thermal comfort indicators such as PMV may also be assessed during this process.
Why this matters
Using the JV3 assessment method ensures that a building’s energy performance remains compliant, even when the design diverges from standard prescriptive requirements. It gives confidence that innovative architectural choices can still meet the legal and efficiency benchmarks set by the National Construction Code. This approach allows for smarter trade-offs between design elements—such as insulation, glazing or services—so energy targets are met without over-specifying materials, ultimately helping to optimise both construction costs and operational efficiency.
How Certified Energy can help
We develop both the reference and proposed building models with a high degree of precision, using industry‑leading thermal simulation tools and strict internal quality control processes to validate all assumptions and inputs. Our team carefully evaluates where design trade‑offs can be made—for example, adjusting glazing, insulation or service efficiencies—to meet JV3 compliance. The final report clearly outlines whether your proposed building meets the NCC performance requirements and includes practical recommendations if adjustments are needed to bring the design in line with the reference model.
Related regulations
-
NCC Volume 1, Section J Verification Methods – JV3 / Specification JV.
-
Climate zone definitions in NCC.
-
ASHRAE / PMV standards for thermal comfort where required.
Helpful resources
.jpg?width=6000&height=3376&name=dylan-ferreira-sg3QrWSHw2s-unsplash%20(1).jpg)
