JV3 Modelling

A Proven Method to Reduce Construction Costs.

Geoflow-Jv3 Energy Modeling

Why JV3 / Section J energy modelling?

JV3 modelling is a risk-free energy compliance pathway that helps to achieve one or more of the following design objectives: 

What GeoHeat offers

Glazing can be a significant construction cost component, and the manner in which the National Construction Code (NCC) handles glazing often makes it much more expensive than necessary.

This unnecessary cost impost is due to the default energy assessment method for glazing in buildings under the Deemed to Satisfy (DTS) provisions, wherein glazing is assessed in isolation to the rest of the building fabric (i.e. walls, floors and roof). Fortunately, the NCC allows an alternative solution for energy efficiency compliance assessment, called JV3.  

The JV3 assessment method provides the ability to model glazing and all other building components as a system. So, for example, specifying a lower thermal performance window can be offset by increasing the amount of insulation in the roof space.

Similar compliance pathway is also available for residential dwellings and is called Verification Using a Reference Building (VURB) which allows going beyond NCC Vol 2 Part 3.12 energy efficiency provisions.

Under the JV3 assessment methodology:

GeoHeat - JV3 Glazing Performance Solution

How the JV3 assessment process works

NCC Reference Building Energy Modelling requires a reference case building to firstly be modelled in accordance with the Deemed to Satisfy (DTS) provisions. Then the greenhouse gas emissions generated by the services of the reference building are then compared to that of the proposed building. The greenhouse emissions of the proposed building must be less than, or equal to, that of the reference building. 


This approach provides the ability to specify in the proposed building, for example, increased insulation thickness in the roof to minimize the glazing requirements (e.g. double or triple glazing), thereby providing an overall construction cost saving to meet energy compliance requirements.


If the proposed building’s annual greenhouse gas emissions is even 1% less than that of the reference building, then the proposed building is deemed to comply with the NCC minimum energy requirements. JV3 energy modelling is also called JV3 modelling, Section J report, commercial energy assessment, performance modelling, alternative solution, Verification using Reference Building (VURB) and section J modelling.

Why choose GeoHeat:


Market competitive rates for all project sizes

Fast turn around

Guaranteed delivery in one working week

Bigger saving

Cheaper construction costs compared with using Deemed to Satisfy method (DTS).

Value Guarantee

GeoHeat guarantees that our JV3 energy assessment service will reduce the building construction cost more than the cost of GeoHeat’s service fee. If not, then it’s a free service!

Our Invitation

GeoHeat has been providing energy assessors and architects with this service at a fee similar to providing simpler 6-Star energy ratings.  Our clients have been very appreciative, and have enjoyed large construction cost savings, with single-pane glazing replacing double/triple-pane glazing.


If you have a project with high-cost glazing, we are here to help you.  The cost of our service has in some cases been less than 5% of the overall cost saving to the client.

We also provide other unique energy efficiency solutions for large scale commercial applications, such as shopping centres and for industrial process heating or cooling.

GeoHeat Jv3 Annual Energy Concupmtion (kWh) Reduction

Other Services

Selection/Design of Renewable Systems

Choosing the right renewable energy system to optimally use the available land/roof space, is the key to maximising onsite energy generation. The hour-by-hour energy modelling results allow us to design and investigate the hourly cost saving from different renewable systems, such as solar thermal for space heating and hot water storage, or solar electricity and battery storage, or a geothermal solution, etc.

Following BESS Best Practice for Victorian developments is also associated with JV3 modelling and satisfy both the NCC energy efficiency provisions and the Council’s ESD requirements.

GeoHeat Sustainable Energy Solutions

Lower Energy Operating Cost

Our approach is to assist architects/building owners to use our service to firstly minimize the heating and cooling demand of the building, and then find a cost-effective renewable energy system for the building to achieve close to a net zero carbon footprint. 

GeoHeat is assisting architects to win more jobs by including energy efficiency and daylight modelling as a key part of design and material selection.

Energy Modelling is a Decision-Making Tool to Achieve Cost-Effective High-Efficiency Building 

A detailed Energy Simulation completed during the early design phase will quickly show the potential energy and utility cost savings associated with any number of possible building fabric, lighting, renewables and HVAC options. However, energy modelling also proves to be a useful tool for a major alteration or extension to an existing building. The predicted energy savings will be incorporated in Simple Payback, Return on Investment, and Life Cycle Costing analyses to determine the optimum solution for your building.


There are also some limitations to use JV3 modelling. For example, apartments (Class 2 buildings) cannot have JV3 modelling as a compliance pathway and can only use NatHERS Star Rating which is a Deemed To Satisfy compliance pathway for residential developments.

GeoHeat 3D Energy Modelling
Modelling Dynamic Interaction Between Building and Different Energy Systems

Modelling Dynamic Interaction Between the Building and Different Energy Systems


GeoHeat models the dynamic interaction between the building and the proposed energy system(s) for a typical year, so that the long-term cost saving of the solution is determined. Our engineers properly model the building energy system(s) to enable architects to confidently assess different renewable energy options – not based on rules of thumb or guesses, but on actual kWh’s and $ savings. This ensures that the building owners achieve the pre-quantified benefits from their energy efficiency investment.

Daylight Modelling and Dynamic Artificial Lighting Control and Modelling


Daylight modelling includes detailed simulation of the amount and quality of natural light entering a building.  The daylight simulation can estimate the amount of light entering a space and predict the energy savings from dimming the electric lighting.  This simulation allows the team to address glare issues during the design stage, by proper selection of overhangs, louvres and glazing.

GeoHeat Daylight Modelling and Dynamic Artificial Lighting Control and Modelling
Esd and NCC Energy Efficiency Compliance

ESD and NCC Energy Efficiency Compliance

GeoHeat provides Ecologically Sustainable Development (ESD) report covering: Energy Efficiency, Transport, Water Efficiency, Waste, Indoor Environment Quality, Building Materials, and ESD excellence.  Energy and daylight modelling contributes to a number of potential scores in ESD assessment for commercial projects.

GeoHeat’s energy modelling is based on JV3 – verification using a reference building method, and it replaces the Deemed To Satisfy (DTS) method in NCC.  We use DesignBuilder and TRNSYS software and 3D realistic modelling that provides hour-by-hour heating and cooling loads.

This hourly output data could then be used for various optimisation and renewable system assessment purposes.

Modelling Tools

GeoHeat uses the state-of–the-art DesignBuilder and TRNSYS design platforms that allows hourly thermal modelling of the building (in 3D) and multiple renewable energy systems in a single model.  This allows the client to consider the dynamic interaction between different energy systems including: Geothermal, Solar Thermal & Storage, Solar Electricity & Storage, all in a single model for a typical year and to compare efficiency, saving and payback periods from the different options.

Other tools that we use for our JV3 and feasibility assessments are:
FirstRate5, Carrier HAP, LEAD, LBNL WINDOW, STORM, NREL System Advisor Model, AutoCAD, Revit.

Building thermal simulation for passive and active solar systems

With skyrocketing gas and electricity prices, many property owners that are planning to build a high-end house are willing to invest in house energy efficiency. Our approach is to assist architects to use our service to first minimize heating and cooling demand of the house and then size a cost-effective renewable system for the house.

Every new house needs to comply with the National Construction Code (NCC) energy efficiency provisions to be able to get a building permit. Most architects satisfy these provisions with 6 Star rating which doesn’t provide any real-life data for the building. Our solution is what is called Verification using a Reference Building Method in NCC (Section and it replaces the 6-Star rating with a 3D realistic modelling (TRNSYS) that provides hour by hour heating and cooling loads. GeoHeat then liaises with the architect to develop optimised cost-effective solutions, to further reduce building heating and cooling demand. Below is an example of an off-grid house in Moorabool. Working in conjunction with the architect, GeoHeat managed to significantly reduce the house energy demand to less than half of its initial value under 6 Star Provisions.

GeoHeat passive house energy modelling significantly reduce the house energy demand

While satisfying the NCC energy efficiency requirements, our modelling software (TRNSYS) enables us to further investigate active solar solutions like solar thermal for space heating and hot water storage tank or solar electricity and battery storage or geothermal solution, etc. GeoHeat models the dynamic interaction between the building and the proposed energy system(s) for a typical year, so that the long-term cost saving of the solution is determined. Our engineers properly model the building energy system(s) to enable architects to confidently assess different design options – not based on rules of thumb or guesses, but on actual kWh’s and $ savings. This ensures that home owners achieve the pre-quantified benefits from their energy efficiency investment.

Contact us to discuss how we can assist you with your large residential building design.

Passive House Design

We define a passive house as a house that requires cost-effectively, minimum amount of mechanical heating or cooling. Homes that are passively designed take advantage of natural climate to maintain thermal comfort. 

With passive solar design we try to limit the heat gains in summer and heat losses in winter through climate-sensitive design of building envelope. A house built using passive solar design principles will generally be much less reliant on artificial heating and cooling and will, therefore use less energy and cost less to run. The passive house design is essential for houses that are planned to be off the grid. Lowering building demand allowing to lower the capital investment on solar electricity and battery and solar thermal heating/cooling and hot water storage tanks. 

The key principles of passive solar design (with the correct order) are as follows: 

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1- Orientation and siting

2- Zoning and layout

3- Thermal mass

4- Common building elements, such as walls, floors and roofs

5- Floor type and materials

6- Windows and glazing

7- Shading, including use of eaves

8- Convection and ventilation

9- Insulation

10- Landscaping and vegetation.

Note for the order of different principles above as it is the key for to a cost-effective passive house design. Homeowners don’t need to invest several tens of thousands in excessive and unnecessary insulation where a proper modelling and design can reveal cheaper options to better take advantage of natural climate at lower installation costs. 

At GeoHeat, we use TRNSYS software to model all building’s thermal details in 3D. TRNSYS is the most advanced thermal modelling software that is used in industry and research for implementation of new innovative energy systems. Modelling in 3D allows considering almost all the details for the building thermal modelling. It also minimizes errors in modelling as you can see the building in 3D and compare it with architect’s plans. Neighbouring buildings and objects can be exactly modelled and shading effects can be assessed for any time of the year. Internal heat gains by occupants and schedule of operation can be modelled as requested by homeowners every detail. The most important final output of modelling is hourly building heating and cooling demand and electricity/gas/hot water consumption. 

At GeoHeat we want to achieve the lowest building energy demand with cheapest energy efficiency options. For instance, we won’t consider triple glazing with an aluminium frame and thermal break where a double glazed UPVC window can deliver similar saving at half the cost. We model different energy efficiency options and assess annual hourly building loads and savings for each option and let the architects/builders/homeowners decide based on annual cost saving which options they want to take. 

Because the climate varies so much across Australia, the passive design is not a single set of strategies all of which are applied equally in every house and climate. For instance, higher shading is desirable in a warmer climate where it can lead up to increased annual demand in mild and cool temperate. Same applies todifferent types of glazing. Warm climates should minimize heat gain from glazing whwere in the in the cool temperate, different type of glazing are used to increase solar heat gain during the day. At GeoHeat, we use appropriate strategies in our modelling to take into account the climate and specifics of the site to minimize the heating and cooling requirements of the building, cost of running the building and consequently the carbon footprints of the building.

In the following summary of key points for the different passive house design principles are discussed. 

Co-benefit of hourly energy modelling

The co-benefits of GeoHeat’s passive solar modelling is to use data from passive house modelling to design your renewable energy system. Sometimes, for some people, this co-benefit becomes the major focus. One of the key outputs of GeoHeat’s energy modelling is hourly energy outputs. These hourly outputs can be used to find peak demand, annual total heating/cooling demand, annual total electricity to run appliances and annual total hot water demand. The software can also show any heat loss/gain from any part of building envelope like a window, walls, etc., for any time of the year which comes handy when comparing options like different glazing from different manufacturers. 

GeoHeat hourly heating and cooling energy modelling
The output of building thermal modelling – hourly heating and cooling for the building

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These hourly outputs are the key for proper design of renewable energy system as a source of energy. With conventional energy sources like grid electricity, split heating, gas heating, etc, annual demand is not a design factor as they are unlimitedly available as long as you pay for the bills. However, with renewable energy generation for yourself, it is important to know hourly and annual demand for energy to be generated to cost-effectively spend the available capital. Renewable energy generation system for your house includes but not limited to solar electricity, battery storage, geothermal and solar thermal heating/cooling. The oversizing and wrong design could cost a lot of capital investment which could have been used more cost-effectively. 


TRNSYS software allows modelling almost any energy source system like geothermal, solar electricity and solar hot water to be designed for best satisfaction of the building demand for every hour of the year. In other word, our passive solar design enables us to use data from passive house modelling to use for your solar hot water and electricity generation and storage design. 




Table below shows the Minimum insulation according to NCC for major cities climate zones

General insulation principles:

Bulk insulation is more effective above the ceiling that under roof. Reflective foil is more effective under a roof than above ceiling. Walls can be effectively insulated with bulk and /reflective foil insulation. However, if the foil the effectiveness of foil insulation will be reduced if there is not enough still air gap in front of the foil.


shadingIn heating dominant areas, unwanted shading from eaves is probably the most important factor affecting the thermal design of the house. As shown in the picture, the area immediately below a horizontal building element like an eave is virtually permanently in shade. In climates that can benefit from solar gains for heating in winter, it is important to ensure that any fixed horizontal shading device doesn’t keep the top of glazing in permanent shade. A shaded area of glass makes no contribution to winter solar gain and can lead to a large amount of heat losses to ambient.

Even use of thermal mass elements in the permanently shaded area is useless as they are never exposed to warmth. It is important that eaves dot restrict the solar access of mass elements. Thus in climate zones where heating predominates, top of the window must be far enough below the eave to prevent overshadowing at mid-winter. Providing a clearance between horizontal overhangs and top of the window is an important low-cost strategy thermal performance of the house.

GeoHeat Modeling Software

Here a description of modelling tools used by GeoHeat is presented so our clients can rest assured that we don’t use rules of thumb at cost of our clients.

TRNSYS Software for 3D building thermal modelling

We use TRNSYS 3D building modelling which allows drawing a multizone building by considering thermal mass, self-shading, external shading and internal view factors for radiation exchange. The data we need for modelling is the building plans, elevations and specifications if they are available.

TRNSYS is the most comprehensive suite of tools that allows modelling the building, geothermal heating and cooling, solar electricity, solar thermal and any other thermal phenomena in a single model and assess the interaction of different systems on each other.

 3D simulation with TRNSYS

6-Star Energy Bands

According to the NatHERS star rating protocol, star bands are introduced for NatHERS building modelling approach to assigning star rating for residential buildings.The figure below represents the star bands for 67 different cities in Australia. For instance, Melbourne is called climate region 21 and to achieve 6-star rating, the building must not consume more than 114 MJ/m2 or 31.6kWh/m2. In other words, theoretically, a 200m2 6-star building in Melbourne annual heating and cooling energy demand shall be about 200*31.6kWh/m2= 6320 kWh.

The below star bands are valid for a house of 200m2. For smaller or bigger houses, the star rating is adjusted to consider the surface area of the house. For bigger houses, this adjustment is like a fixed penalty for house star rating regardless of the quality of building thermal fabric.

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Star rating adjustment with building foot print area

Sustainability Victoria $7500 Energy Assessment grant

As of May 2018, Sustainability Victoria is offering two non –competitive energy assessment grants for businesses spending over $20,000 a year on energy:

Basic energy assessment grant: Up to $2000 towards the cost of a basic energy assessment and a further $3000 bonus to implement energy efficiency actions. This is recommended for businesses spending between $20,000 to $50,000 on energy per annum.

Funding example: For an assessment quoted at $2600, Sustainability Victoria (SV) funds $2000, the business funds $600. The assessment report recommends an energy saving project costing $3000, SV funds the $3000 to undertake the project.


Detailed energy assessment grant: Half the cost of an assessment up to $15,000 and a further $5000 bonus to implement energy efficiency actions. This is recommended for businesses spending more than $50,000 on energy per annum.

Funding example: For an assessment quoted at $8200, SV funds $4100, the business funds $4100. The assessment report recommends an energy saving project costing $5000, SV funds the $5000 to undertake the project.


As this is a non-competitive program, a Business Productivity team adviser is available to guide you through the application process.


GeoHeat has been involved in this program for a long time and we are one the approved assessors with Sustainability Victoria. GeoHeat’s energy assessments are based on or equivalent to a Type 2 Energy Assessment (Australian Standard AS/NZS AS3598.1:2014, AS/NZS S3598.2:2014). You can read more about this grant here.


Contact us for our state of art energy assessing today


NatHERS Star bands (Source: FirstRate5 Software manual, page 16, published Jan 2015)

 Star rating adjustment with building foot print area




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Geoflow Australia Pty Ltd

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Our partner for solar thermal


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24 Aisbett Avenue,
Camberwell, vic 3124




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