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Alternative Assessments

Large boarding houses – alternative assessment process

We have developed an alternative assessment process

How does BASIX work with large boarding houses?

We have developed an alternative assessment process to be used to assess the thermal comfort of large boarding house developments (i.e. those designed to accommodate more than 12 people or with a gross floor area of more than 300m2). Large boarding houses include student accommodation developments that meet the above criteria.

If the development is a small boarding house (i.e. it does not meet the above criteria), you should complete a standard 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 Building Code of Australia (BCA). This means that you do not have assess the thermal comfort of the development as part of the BASIX assessment.

NB: This alternative assessment process is only applicable to large boarding houses.

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. 

What if the building has dwellings larger than 35m2?

If there are dwellings in the building that are not boarding house rooms (i.e. 35m2 or larger), the alternative assessment process does not apply and a thermal comfort assessment of such dwellings is required.

Is there an additional fee for an alternative assessment?

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).

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 are ≥ 35m2 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 ≥ 35m2 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 ‘Assessor Details’ 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) ≥ 35m2, 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 BCA. 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 heating load and cooling load values for dwellings ≥ 35m2 for which you have completed a NatHERS assessment.


If you have any questions, please email and include ‘BASIX – large boarding house’ in the subject.