Alternative assessment - Large boarding house

If your project is a boarding house (which includes student accommodation) and meets all the criteria below:

    • it is designed to accommodate more than 12 people, or the total floor area exceeds300 m2
    • at least 80% of the dwellings are less than 35 m2, and
    • it only comprises residential flat buildings.

please use the Large boarding house thermal comfort method.

If the boarding house meets the first criteria, but does not meet the second or third criteria, you should apply for an alternative assessment as a large boarding house, as outlined below. This may be where the project:

  • contains a mix of class 3 boarding house dwellings and larger class 2 apartments, or
  • comprises a large boarding house and a single dwelling house on the same site.

Projects that only contain apartments, including serviced apartments, are not eligible to apply for an alternative assessment as a large boarding house.

If the development is a small boarding house (i.e. designed to accommodate 12 people or less, and has a total floor area of 300m2 or less), you should complete a BASIX assessment using the single dwelling tool and assess the thermal comfort of the building as a whole

What is the alternative assessment process for large boarding houses?

The alternative assessment process allows the thermal comfort of a large boarding house development 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 means that you do not have assess the thermal comfort of the development as part of the BASIX assessment.

Why has this alternative assessment process been introduced?

We have introduced the new process because NatHERS accredited software is unsuitable to model the thermal comfort of individual boarding house rooms.

Is there an additional fee for an alternative assessment?

Yes. There is an additional fee of up to $250 for an alternative assessment. The fee depends on the number of boarding house rooms. To calculate the total fees payable, including both the standard BASIX certificate fee plus the alternative assessment fee, download the  BASIX cost calculator spreadsheet.

How do I request an alternative assessment?

The process is as follows:

    1. Check that the development is a large boarding house (i.e. it is designed to accommodate more than 12 people or has a gross floor area of more than 300m2) but does not meet all the eligibility criteria to use the Large boarding house thermal comfort method.
    2. Identify the climate zone in which the development is located by referring to the NatHERS climate zone map.
    3.  Refer to Table A of the BASIX Thermal Comfort Protocol  on page 19, and identify, for that climate zone, the maximum heating load and maximum cooling load for a ‘Unit’ (which represents the “average all dwellings in multi-dwelling developments”)..
    4. Identify any dwelling(s) in the proposed buildings that will be classified as class 2 and arrange for a NatHERS thermal comfort assessment of those dwellings
    5. Open the BASIX Tool and create a new multi-dwelling project for the development. Enter the number of residential flat buildings and complete the assessment as outlined below..
    6. In the BASIX Tool, go to Thermal comfort / Simulation and enter information as follows:

      • On the ‘Assessor Details’ tab:
        • Enter the assessor details
        • For the ‘Certificate number’, if there are dwellings for which you have completed a NatHERS assessment, enter the NatHERS certificate number. If not, leave the ‘Certificate number’  blank.
        • For ‘Select the zone indicated on your Assessor Certificate’, it will show the climate zone based on the address details you entered – do not change this.
      • On the ‘Thermal loads’ tab:
        • Select ‘Apply Identical Values’ and then from the drop-down menu ‘Apply values to’, select ‘All dwellings’.
        • For the ‘Area adjusted heating load’ and ‘Area adjusted cooling load’, enter the heating cap and cooling cap values that you identified in step 3 above.
        • For any dwelling(s) for which you have completed a NatHERS assessment, revise the ‘Area adjusted heating load’ and ‘Area adjusted cooling load’ values to match the values from the NatHERS assessment (step 4 above).
    7. In the BASIX Tool, complete the Water and Energy sections and ensure that the proposed development achieves scores sufficient to pass both these sections.

    8. In the BASIX Tool, go to BASIX Certificate / Alternative Assessment and click on ‘Apply’ to request an alternative assessment of the development. Select ‘project details’ on the application form and provide a brief summary of the proposed development.

Your request for an alternative assessment will be managed by the BASIX Team. Once we receive your request, we will email you to ask you to provide the plans for the development.

We will advise you if your application is successful. You then need to generate a BASIX certificate and pay the applicable fee.

Please note that the BASIX Certificate will contain an additional commitment for the development proponent to assess the development against the Section J requirements of the NCC – Volume 1. As it will be part of the development consent conditions, the proponent will need to satisfy this requirement prior to obtaining a construction certificate.

Please also note that the BASIX certificate will only show the heating load and cooling load values for dwellings for which you have completed a NatHERS assessment.


If you have any questions, please email This email address is being protected from spambots. You need JavaScript enabled to view it. and include ‘BASIX – large boarding house’ in the subject.