Thermarate is a building physics consultancy. We model how a house really performs, down to the heat moving through its frame, then use the full breadth of the National Construction Code to find the compliance pathway that fits the design.
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Credentials
Australia’s largest team of in-house NatHERS accredited assessors.
More than 20 years in, we know the star-rating pathway better than anyone. That’s why we know when a design deserves a smarter one.
NatHERS and Whole of Home ratings, H6V2 Performance Solutions for houses, every Section J method for commercial buildings, modular included, and life cycle assessments of embodied carbon, all under one roof.
Our accredited assessors are Thermarate staff, not contractors. Ratings for most homes come back within one business day of complete plans.
The minimum for a NatHERS assessor is a Certificate IV. Thermarate is led by a university-qualified civil and structural engineer, with dynamic simulation and thermal bridging analysis behind every recommendation.
01Approach
A star rating tells you whether a design reaches a target. We want to know why a house uses energy. So we model the building itself, hour by hour, then find the route through the Code that suits it. It’s the difference between meeting a target and understanding a building.
hours in the typical climate year every model runs through
models: your design, and the Code’s reference version of the same house
tests in climate zones 2–7: heating and cooling, each against the reference
design brief, agreed with your building surveyor before we model
02The Code
The NCC’s heating and cooling requirement for houses, H6P1, can be met by a Deemed-to-Satisfy Solution or a Performance Solution. Each pathway tests something different. We work across all three, and we’ll tell you which suits your design.
Select a pathway to trace it on the map
Tests the design against a fixed star band for its climate zone, corrected for floor area. Seven stars is the minimum for this route in most states. NatHERS is now branded Home Energy Rating. Our accredited assessors deliver it in-house.
Often suitsDesigns that reach the band without costly upgrades, or where a star certificate is needed for a loan or sale.
Sets prescribed requirements element by element: insulation, glazing, building sealing and more. No simulation is involved.
Often suitsStraightforward designs that meet every prescribed value as drawn.
Compares your design with a reference version of the same house, built to the Deemed-to-Satisfy Provisions. In climate zones 2 to 7, heating and cooling must each be no higher than the reference.
Often suitsDesigns where reaching the star band means a long or costly upgrade list.
A Pathway Check compares the routes for your plans. When NatHERS is the better route, we say so, and we can deliver that too.
Compare the routes in detail03How H6V2 works
We simulate the house through 8,760 hours of climate data for its location, as H6V2 requires: heat moving in and out of the building, hour by hour, rather than a single score.
We model the house as drawn, then the same house built to the Deemed-to-Satisfy Provisions. Same plan, windows, schedules, thermostats and occupancy. Only the fabric, glazing performance and shading can differ.
If your design needs no more heating and no more cooling than the reference, it meets the Performance Requirement. In climate zones 2 to 7 each load must pass separately, which in WA is stricter than the combined NatHERS test.
NatHERS climate file. Outdoor temperature for every hour of Perth’s typical year, one cell per hour: winter nights in deep blue, the hottest summer afternoons in lime.
Illustrative. The reference is a hypothetical house: the same building, built to the Deemed-to-Satisfy Provisions.
Illustrative. Each load is compared with the reference on its own. Both must pass.
04Commercial buildings
For commercial buildings, Section J of NCC Volume One sets the energy requirements. We deliver every method it allows, from Deemed-to-Satisfy reports to J1V3, its Verification Method using a reference building and the commercial counterpart of H6V2.
One principle: verification using a reference building
05Building physics
Every compliance model, ours included, checks a design under standard assumptions. Our building physics work answers the questions those models leave open: how hot the house runs without air-conditioning, how it will cope with a warmer climate, and whether it was built the way it was modelled.
Hourly simulation in engines that meet ANSI/ASHRAE Standard 140, used for design decisions as much as for compliance.
SimulationTwo-dimensional heat-flow modelling of frames and junctions, like the wall at the top of this page.
FramingA rating assumes heating and cooling are always available. We test how hot the house runs without them.
ComfortCompliance uses historical weather. We re-run the design against projected climates to show how it will age.
ClimateModels assume the house is built as drawn. An insulation check at handover, and a re-check of any substituted product, show whether it was.
VerificationEvery model we issue is checked by a second modeller. We review models prepared by others, too.
Review06Research & development
Some of Australia’s largest building-product manufacturers engage us for research and development in energy efficiency and NCC compliance: how a framing system, roof or wall performs inside a real building, and how that performance is demonstrated under the Code.
How framing systems perform once thermal bridging is counted, and how that is represented in compliance models.
How envelope products change heating and cooling loads and summer comfort across Australian climate zones.
The modelling and evidence that show how a product or system can contribute to NCC compliance, route by route.
Much of this work is confidential. We’re glad to discuss relevant experience with prospective clients. More on our research
Discuss a research project07We show our working
A Performance Solution carries more process than a rating, not less: a design brief prepared with the relevant stakeholders, the analysis, an evaluation against agreed criteria, and a final report. We start with your building surveyor, and we write every reference assumption down.
“All compliance options aim to offer an equivalent level of performance.”
ABCB · Housing energy efficiency handbook (2024), pp 10 and 111
08Our standard
Put our quote for a Performance Solution beside the others and compare what’s in it: two full models, a design brief agreed with your surveyor, sensitivity testing and a formal report. It is priced as the specialist work it is.
Then compare the total, not the fee. On the right design, the upgrades a Performance Solution removes are worth more than it costs, and the Pathway Check tells you whether yours is one of them before you commit.
Your project is modelled by our own staff and checked by a second modeller, not passed down a production line.
We take on a limited number of projects and model each one properly, from design brief to final report.
If NatHERS is the cheaper route for your design, the Pathway Check says so, and our assessors can rate it. That is what makes it advice.
Our method is written down for your surveyor to check. Nothing rests on a setting no one can see.
09Insights
Short, sourced explainers on the NCC, NatHERS and Performance Solutions. Every claim names its source.
Pathway Check
Plans, elevations, specification and any NatHERS report you already hold. We’ll tell you which route is likely to cost least. Your assessor stays your assessor.