Building Sustainability Index (BASIX)

Last updated: 2 May 2019

BASIX or Building Sustainability Index is a scheme introduced by the government of New South Wales (NSW), Australia in 2004 to regulate the energy efficiency of residential buildings. It offers an online assessment tool for rating the expected performance of any residential development.


BASIX sets sustainability targets for water and energy as well as minimum performance levels for the thermal comfort of the proposed development.


The targets are expressed as a percentage saving against the NSW benchmark. While the benchmark is constant across NSW, the targets are varied to suit regional climates and can be amended over time to achieve State objectives for water and greenhouse gas savings. Variable targets that recognise differences in local conditions (such as rainfall, soil type, and evaporation rates) and different housing types (from single detached houses to high-rise apartment buildings) ensures equity across NSW without placing an excessive cost burden on dwellings in certain regions.


The stringency of BASIX energy targets was increased in July 2017:


A 10% increase in energy targets for low-rise units and houses.

A 5% increase in energy targets to high-rise units.

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