Simulation Method

Passive House Standard method

Passive House, or Passivhaus as it is known in German, is a design standard that requires appropriate levels of insulation, a design that reduces thermal bridges, air tightness, high-performance windows and doors, and mechanical ventilation with heat recovery (MVHR).

Passive House is a performance-based standard that sets the criteria on thermal comfort, space heating and cooling demand/load, indoor humidity, air tightness and annual primary energy demand.

The Passive House Institute (PHI) administers an international certification scheme, carried out by a PHI-approved Passive House Certifier. A certified Passive House undergoes a quality assurance process that ensures that it is built as designed and meets the comfort standards required by the Passive House standard.

Passive House is different from Passive design. Passive design principles result in a design appropriate to the climate that the dwelling is located. By utilising the Sun and cooling breezes, passive design helps reduce space heating and cooling while maintaining a comfortable temperature range within the home.

The Passive House standard method is available to both single and multi dwelling developments.

In the Passive House standard method, you will need to:

  • Engage a Certified Passive House Designer who will simulate the dwelling design with the Passive House Planning Package (PHPP); and
  • Enter the name of the Certified Passive House Designer into BASIX.

The Australian Passive House Association can help you locate a Certified Passive House Designer to your project.

Currently the Passive House standard method is only available to certain locations in NSW, where it is demonstrated that the thermal performance of dwellings satisfying the Passive House standard is at least as good as those passing the BASIX Simulation method. Note that Passive House assessments do not directly correlate to outcomes from the Simulation method using NatHERS accredited software.

If the Passive House standard method is not available to the location of your dwelling, please contact your Certified Passive House Designer or the Australian Passive House Association.

After you generate the BASIX certificate with the Passive House standard method, you will need to attach it to a PHPP software report issued by the Certified Passive House Designer to the BASIX certificate and submit to the Council or the certifying authority. The verification section of the PHPP software report needs to show that your dwelling satisfies the space heating, space cooling and air tightness requirements of the Passive House standard.

The Certified Passive House Designer or Passive House Certifier needs to provide a written endorsement that the plans and documentation provided have been assessed in accordance with the Passive House standard. The template for written endorsement can be accessed here.

After the construction of your dwelling is completed, you will need to engage a tester registered with the Air Tightness Testing and Measurement Association (ATTMA) to conduct an onsite blower door test. Results from the onsite blower door test must show that air tightness of the dwelling does not exceed the 0.6 air changes at 50 Pascals pressure (ACH50) as required by the Passive House standard. You need to attach the results of the onsite blower door test to the BASIX certificate when applying for the occupation certificate.

Ceiling fans

Ceiling fans in the Simulation method

The 27/11/2020 revision to the thermal comfort protocol allows ceiling fans to be included in thermal simulations (previous versions of the protocol did not). If ceiling fans are used in thermal simulations, this must be indicated in the Assessor Details section of the Simulation method.

The location of ceiling fans must also be included on the plans accompanying the development application and the application for a construction certificate or complying development certificate. The location of ceiling fans may be either indicated on the drawings or via a table on the plans. 

Large boarding house thermal comfort method

This method can only be used for boarding houses (which includes student accommodation) that meet all the criteria below:

    • it must be designed to accommodate more than 12 people, or the total floor area must exceed 300 m2
    • at least 80% of the dwellings must be less than 35 m2, and
    • it may only comprise residential flat buildings.

If the boarding house doesn’t meet all these criteria, but does contain dwellings of less than 35 m2, you may apply for an alternative assessment as a large boarding house.

The large boarding house thermal comfort method allows the thermal comfort to be assessed at a later stage (i.e. the construction certificate stage) against the Section J requirements of the National Construction Code (NCC) – Volume 1. This is because NatHERS accredited software is unsuitable to model the thermal comfort of individual boarding house rooms.

The method does not require you to input any data for heating and cooling loads. Instead, the Tool automatically enters values for heating and cooling loads equivalent to the heating and cooling caps in the climate zone of the project.

Simulation method FAQs

This page summarises the common queries and responses about the BASIX Simulation method.

 

QUESTION 1: Communications from the Department indicate that the BASIX energy targets are increased by up to 10% from July 2017, but I found that the heating and cooling caps are changed by more than 10%. Please clarify.

The ‘10%’ increase refers to the change in the BASIX energy targets. For single detached houses in coastal NSW, the energy target has increased from an energy target of 40 to 50.

The heating and cooling caps are related to the BASIX thermal comfort section and not the energy section. As part of the BASIX changes in July 2017, the thermal comfort stringency was increased to better align with the requirements imposed in other states and territories. Changes in heating and cooling caps in some climate zones are higher than 10% from their pre-July 2017 values.

 

QUESTION 2: Is the thermal comfort stringency in BASIX equivalent to NatHERS 6 stars, as required in other jurisdictions by the National Construction Code (NCC)?

The combined heating and cooling caps in BASIX are equivalent to NatHERS 5 stars for concrete slab on ground constructions of detached houses. The average heating and cooling caps applicable to multiple-dwellings projects are also equivalent to NatHERS 5 stars. Other jurisdictions do not have separate heating and cooling caps and evidence suggests that there is a 0.5 – 1 star over-compliance to satisfy the separate heating and cooling caps in BASIX.

Heating and cooling loads from the thermal comfort section will be carried over as the energy demand for space heating and cooling in the BASIX energy section. Due to this interaction between the thermal comfort and energy sections (which is unique to NSW), BASIX-affected dwellings passing both the thermal comfort and energy sections are regarded as having achieved the equivalent of 6 stars. 

 

QUESTION 3: My project cannot pass the heating and/or cooling caps using Simulation method. What should I do?

Simulation method provides more flexibility on design to pass the heating and cooling caps. You may need to discuss with the NatHERS accredited assessor and/or the architect to explore ways to improve the design and to reduce the resultant heating and cooling loads.

Alternatively, increasing the level of insulation and/or improving the specifications of the glazing will help reduce the heating and/or cooling load. In some cases, these upgrades may not be as cost-effective as changes in design. Increasing insulation levels may also increase the risks of condensation in buildings.

 

Assessor details

How to complete the Assessor details page

This help note only refers to Thermal Comfort assessments done by Accredited Assessors using the simulation method (NatHERS software). This applies to both BASIX Single and Multi development tools. 

1. Select the appropriate ABSA or BDAV radio button.

The accredited assessor that assessed your project for thermal performance will either be accredited by the Australian Building Sustainability Association (ABSA) or Building Designers Association of Victoria (BDAV).

Sample screen of BASIX assessor certificate - select the appropriate optionSample screen of BASIX assessor certificate - select the appropriate option

2. For BDAV members:

If you selected BDAV as your assessor type then you will need to complete the required details by manual entry.

Sample screen of BASIX assessor certificate - enter required textSample screen of BASIX assessor certificate - enter required text

3. For ABSA members

Do you have ABSA's XML file to upload?

  • If you selected ABSA as your assessor type and do not have the xml file click "No" and enter required details manually (refer above step 2 for BDAV)
  • If you selected ABSA as your assessor type and have the xml file supplied click "Yes".
Where do I get the ABSA xml file?

The XML file containing the information required for the BASIX certificate can be obtained by ABSA members from the ABSA Rating Certification System website.

This is the screen that you will see on the ABSA RCS website for a single dwelling project. The ABSA website allows you to download a project This is the screen that you will see on the ABSA RCS website for a single dwelling project. The ABSA website allows you to download a project

 

 

Example of a downloaded ABSA fileExample of a downloaded ABSA file

Once downloaded to your computer, the file may be uploaded to BASIX, or emailed to a third party for them to complete the thermal comfort section of the BASIX Certificate.

To upload your xml file to BASIX:

  • Click "Browse" button
  • Select the file from its location on your computer.
  • Click the "upload ABSA file" button

Once successfully uploaded details of the file will appear on the screen:

Sample screen of BASIX Assesor Certificate - File successfully uploadedSample screen of BASIX Assesor Certificate - File successfully uploaded
If you uploaded the wrong file, or need to upload a revised file, click "delete file" and repeat the process of selecting another file. Alternatively, you may delete the file and revert to entering the information manually.

4. Do you have in-slab heating?

Select yes or no.

Related BASIX information:

Useful references:




Entering Results

You will need to enter your dwelling's area-adjusted heating and cooling loads, estimated by all the accredited software, from the Assessor Certificate.

To pass Thermal Comfort using the Simulation method, the area-adjusted heating and cooling loads provided by the Accredited Assessor must be less than the maximum loads calculated by BASIX.

You will also need to indicate whether or not ceiling fans have been used in the simulation of your dwelling. See Ceiling fans in the Simulation method.

You must also complete the Project Details, Water and Energy sections of BASIX to generate a BASIX Certificate.

Assessor Certificate

Assessor Certificate means the Nationwide House Energy Rating Scheme Certificate issued from the online generation system by an approved software provider, with the first page showing the NatHERS logo and the unique QR-code.

The QR Code is the unique scannable code which links to the Assessor Certificate and drawing sets.

The first page of the Certificate for individual dwellings contains an overview section, and subsequent pages list the building features of that dwelling.

For a multi-dwelling development such as an apartment building, the Certificate consists of a summary ('Class 2 Summary') that includes the certificate details (including the heating and cooling loads) of the individual dwellings. Certificates of individual dwellings need to be attached to the summary.

Software Tools

Thermal simulation software such as AccuRate (formerly NatHERS), Building Energy Rating Scheme (BERS), First Rate and Hero are simulation programs used to estimate the heating and cooling loads of a dwelling.

The programs calculate area-adjusted thermal loads using standardised behaviour by occupants for operating ventilation openings (windows and doors) and shading devices to ensure their effect on the loads is considered. The loads also include heat gains from occupants and activities such as cooking. The lower the load, the more the house can be comfortable for the occupants without needing air conditioning or heating.

The heating and cooling loads predicted by thermal simulation software do not include the efficiency of heating and cooling equipment or the fuel type used- these aspects are assessed in the BASIX Energy Index.

Thermal simulation software is only required if using the Simulation method for Thermal comfort. It must be used by an accredited assessor.

The BASIX Simulation method for Thermal comfort assessment accepts only the NatHERS "second-generation" simulation tools (namely AccuRate, BERS Pro, FirstRate 5 and Hero). First-generation tools including NatHERS software are not accepted.

Accredited Assessors

Accredited Assessor means a person accredited by an Assessor Accrediting Organisation (AAO) to conduct Simulations for the Thermal Comfort Index of BASIX.

The Assessor will simulate your dwelling's thermal performance with an approved software tool and provide you with an Assessor Certificate.

An assessor may work with you to change the design and/or the proposed construction types so that the heating and cooling loads of the proposed dwelling achieve the required BASIX standards by the most effective means.

There are currently three AAOs recognised in NSW:

These organisations can help you locate an assessor suitable to your project.

Checking the assessor certificate details

Assessor Certificate: means the Nationwide House Energy Rating Scheme Certificate issued from the online generation system by an approved software provider, with the first page showing the NatHERS logo and the unique QR-code.

Assessor Certificate Number: means the unique Certificate number shown on the Assessor Certificate.

The Assessor Certificate Number may also be referred to as the 'Certification Number'.

The Assessor Certificate shows:

  • the location of the project;
  • the version of Approved Software used;
  • the Accredited Assessor who generated the certificate;
  • the Accrediting Organisation of the Assessor who carried out the assessment;
  • the conditioned floor area and unconditioned floor area of the dwelling; and
  • the adjusted heating and cooling loads (total load may also be included).

The front page of the Assessor Certificate must also include a unique QR-code at the bottom right-hand corner.

Check that all of the Assessor Stamps are complete, signed and consistent. Check that the Assessor Certificate Number shown on the BASIX Certificate matches the details on the Assessor Certificate.

 

It is possible to further verify the validity of an Assessor Certificate by contacting the Accrediting Organisation of the Assessor who carried out the assessment.

For ABSA assessors: www.absa.net.au

For BDAV assessors:www.bdav.org.au

>> Next: Checking the heating and cooling loads

Checking the heating and cooling loads

Simulation is used by the Accredited Assessor to calculate the heating and cooling loads for each dwelling in the project.

For Single Dwellings

For single dwelling projects, check that the heating and cooling loads shown in the BASIX Certificate are the same as on the Assessor Certificate.

Sample BASIX Certificate extract showing the position on page 2 of the Assessor number, the Assessor Certificate Number, and the heating and cooling loads for a single dwelling project.Sample BASIX Certificate extract showing the position on page 2 of the Assessor number, the Assessor Certificate Number, and the heating and cooling loads for a single dwelling project.

 

 

 

 

 

 

 

 

 

 

 

For Multi Dwellings

In a multi-dwelling project, the Assessor Certificate includes a summary of the individual heating and cooling loads for each dwelling.

For multi dwelling projects, check that the heating and cooling loads shown for each individual dwelling in the Thermal Comfort section of the BASIX Certificate are the same as listed in the summary.

 

Sample BASIX Certificate extract showing position of Assessor Number and the Assessor Certificate Number for a multi dwelling projectSample BASIX Certificate extract showing position of Assessor Number and the Assessor Certificate Number for a multi dwelling project

 Sample BASIX certificate extract showing the position of the heating and cooling loads for each dwelling in a multi dwelling project.Sample BASIX certificate extract showing the position of the heating and cooling loads for each dwelling in a multi dwelling project.

 

Checking the accredited assessor details

Accredited Assessor: means a person accredited by an Accrediting Organisation to conduct Simulations for the Thermal Comfort Index of BASIX.

Accrediting Organisation: means an organisation approved by the Department of Planning & Environment to accredit assessors for the purposes of conducting Simulations.

Currently, the Australian Building Sustainability Association (ABSA) and the Building Designers Association of Victoria (BDAV) are Accrediting Organisations
.

Assessor Number: means the unique number assigned to that Accredited Assessor by the relevant Accrediting Organisation (ABSA or BDAV).

It is a requirement that the Simulation for BASIX Thermal Comfort is conducted by an Accredited Assessor. Every Accredited Assessor is issued with an Assessor Number, to assist with their identification. As an Accredited Assessor, they must:

  • have completed relevant training and examination, and stay up-to-date with Continuing Professional Development;
  • conduct Simulation using Approved Software in a manner consistent with accepted standard procedures; and
  • act in a professional manner consistent with the requirements of their accrediting organisation, including quality assurance and holding relevant insurance.


>> Next: Checking the Assessor Certificate details

Checking the development details

 

BASIX Certificate: means a certificate issued by the Secretary of the Department of Planning and Environment in relation to the sustainability of a proposed development. See clause 164A of the Environmental Planning and Assessment Regulation 2000.

Sample BASIX Certificates are shown on the Checking the Heating and Cooling Loads page.

Check that the address or lot details shown on the plans, the Assessor Certificate and the BASIX Certificate all match the details in the development application, or the application for a complying development certificate, construction certificate, occupation certificate.

 

 >> Next: Checking the Accredited Assessor details

Subcategories