BASIX Certificate

BASIX (Building Sustainability Index) is a New South Wales-specific regulatory framework that was introduced in 2004 with the goal of making all future developments under the regulation 40 percent more environmentally efficient than those erected before the scheme.

In a nutshell, it’s an assessment that most residential buildings must perform as part of the development application process when seeking a development permit from your local council.

It has three parts: a thermal component (NatHERS or DIY assessment), an energy efficiency rating component, and a water use component, all of which must be passed satisfactorily by inputting data truthfully into the BASIX web portal.

The Disadvantages of the DIY Method

At first glance, it may seem prudent to fill the whole BASIX report out on your own (for single dwelling buildings this is allowable), but the BASIX Online calculation for the thermal score will cost you significantly more in the long run.

The details laid out in the BASIX certificate are legally binding for the project and the development must be built as such. If the walls are to have R2.0 insulation, then a builder cannot skimp out on that to save costs with R1.0 insulation instead. As such, it makes sense to spend more in the planning and development stage to optimize the building for cost-to-performance which is where the DIY method of the BASIX tool fails hugely.

The thermal DIY method takes only limited factors of your project into consideration such as the window sizing and orientation. A building’s glazing is a large part of its thermal dilemma, as not only is glass a poor store of heat, but acts as a cutout in your wall and insulation letting your conditioned air escape. The DIY method often specifies higher quality glazing such as double paned glass or tinted shading to compensate for the tool’s lack of detail. In the NatHERS assessment, expensive glazing can be compensated for with inexpensive but thicker insulation.

In the lifecycle of the project, the savings of a simple $300 NatHERS assessment are greatly outweighed by the 10’s of thousands saved in energy costs from cradle to grave of the project. In many of our NatHERS assessments, we average client savings of a few thousand by trialling different insulation, glazing and overshadowing parameters which can easily be prototyped in BersPRO (our NatHERS software of choice) vs doing so in the BASIX Online Tool.