Building energy codes have been widely implemented in the world to regulate energy consumption and CO2 emissions from the building sector. In order to assess the impacts of building energy codes on Australian building performance, this paper has compared the energy efficiency requirements of the Building Code of Australia (BCA) with the USA ASHRAE Standard 90.1 and Chinese GB50189, in terms of the building envelope, HVAC chiller efficiency, internal load density, and HVAC temperature set-points. Then, the whole building energy performance simulation has been conducted using EnergyPlus for a typical large office building in Brisbane to contrast differences in efficiency requirements of building energy codes within three countries. The results have shown that the GB50189-2015 and ASHRAE 90.1-2016 demonstrated 25.0% and 20.8% annual energy savings respectively compared to the BCA 2016, together with 312,429kg and 259,955kg annual CO2 emissions reduction respectively. In light of this, recommendations for further revision of the Australian building energy code have been provided.

It is recommended that the BCA be revised to improve the stringency of its energy efficiency requirements, specifically through:

• Improving plug load equipment and lighting efficiency.
• Further improving building envelope thermal performance to reduce building load.
• Explicitly specifying glazing performance requirements.
• Improving chiller efficiency requirements, especially for chillers with capacities greater than 350kW.
• Optimising HVAC cooling and heating set-points and including setback temperature control.