As part of the requirements for DA or CDC approval, you need to conduct an assessment of your home for Basix which comprise of 3 parts

  • Water
  • Energy
  • Thermal – NaTHERS

It is a requirement to get a passing score for each of these to be provided with a Basix certificate and stamped plans.

How to challenge changes you’re told to make to comply

The energy and water component of BASIX is straightforward and relatively easy for anyone to understand. When an assessment is done the assessor will choose different options that you are required to comply with however there are several options available that could be more suitable for yourself.

An example of this is that for the energy component, solar is a common suggestion however a cheaper alternative could be to add an outdoor clothesline. The following will run you through how this works, in NSW

BASIX Options in Detail

By spending a bit of time familiarising yourself with BASIX you will be much more informed about the various options available to you when it comes to your build. Instead of being forced to choose an option by your builder you could suggest suitable alternatives instead.

  1. Create an account on the BASIX portal
  1. Create a new project and then choose one dwelling
Create a new project
One dwelling
  1. Enter the relevant address for your property and the type of dwelling.
Project Address
Project Type
  1. Enter the Site Details. You might not be able to get accurate details from your plans without the help of a draftsman so you can work out these details as close as you can without impacting the water and energy components too much. If you can use software like ArchiCAD or Revit, or if you have the .dwg files you can use these to work out these areas more accurately. Alternatively, ask your builder for these. They will likely ask the assessor to provide this.
Site Details
Site areaThe land size of the property
Roof areaArea of all roof surfaces measured to the outside of the gutters
Conditioned floor areaTotal floor area excluding:
a) floor area that is not fully enclosed;
b) bathrooms (but not ensuites) and laundries, with a ventilation opening; and voids, store rooms, garages
Unconditioned floor areaTotal floor area of all bathrooms (not including ensuites) and laundries, with a ventilation opening.
Garage areaTotals area of garage
Mezzanine areaHabitable areas open to and above a habitable floor, and doesnt include stairs or open passageways, or corridors 1.1m or less wide.
Site Details



This examines the water efficiency of the appliances and fixtures, the design of the landscaping, and the use of alternative water sources in the development.

Enter the landscape area which you may have on your plans or you will need to ask your builder/draftsman for these details.

Water – Landscape

Same passing score but different star rated options

Builders will normally change the taps ratings without much thought and you might be forced into choosing on rated higher then you want. You might prioritise taps having a lower rating so you can choose the ones you like and compromise on the toilets.

Below shows the same passing score but with different options.

Passing score of 40%
Same 40% pass but different star ratings
Rainwater tankA tank designed for the capture and storage of rainwater collected from all roof areas 
Stormwater tankDesigned to capture and store stormwater
GreywaterWastewater that does not contain human excreta. Greywater includes wastewater from the laundry, bath, shower and bathroom basin, but not toilet
Greywater diversion – water re-used for subsurface garden irrigation
Greywater treatment – treated water re-used for garden irrigation, clothes washing, and toilet flushing depending on the level of treatment
Private damCan be used to harvest water for toilet flushing, laundry, and garden irrigation in single dwelling developments only, subject to relevant approvals and licences.
Hot water recirculation or diversion systemDivert hot water draw-off (cold water in the hot water pipe) until the hot water at the fixture reaches the set temperature. The diversion is triggered by the operation of the hot water tap


This examines the energy efficiency of the appliances and equipment and the use of alternative energy sources in the development.

Thermal – NaTHERS

This examines the design and materials used in the building to reduce the need for artificial cooling and heating to keep the home comfortable.

Approval documents

Proof of work

Leave a Reply

Your email address will not be published. Required fields are marked *

Related Post