Thermal Performance

The thermal performance section of BASIX aims to:

• ensure thermal performance for a dwelling's occupants, appropriate to the climate and season;
• reduce greenhouse gas emissions from artificial cooling and heating through good building design and use of appropriate construction materials; and
• reduce the demand for new, or upgraded, energy infrastructure by managing peak demand for energy required for cooling and heating.

The loads from Thermal performance are combined with the selected heating and cooling appliances in the Energy section to calculate the cooling and heating component of your Energy score. Lower loads will improve your Energy score. In cold or hot climates, you may find this is an effective way of obtaining a Pass in Energy.

Thermal performance methods

To complete the Thermal performance section of BASIX, you will need to select one of the following methods:

• Do-It-Yourself (DIY) method - simplified assessment for single dwelling houses that use common construction materials and methods
• Simulation method - detailed assessment that uses National House Energy Rating Scheme (NatHERS) accredited software, and can simulate a larger range of construction methods and materials, more complex designs and multi-dwelling developments such as townhouses and apartments.
• Passive House standard method – This method only applies to single dwelling houses designed and constructed in accordance with the Passive House standard. You need to engage a Certified Passive House Designer to enter the building design information into the Passive House Planning Package (PHPP) software.

The DIY and Simulation method are broadly equivalent across a large sample of dwellings. However, design and compliance outcomes are likely to be different. This is because the DIY method estimates the heating and cooling loads, whereas the Simulation method calculates the loads using thermal simulation software.