Development of an Energy Rating Tool for Australian Existing Housing

Abstract

Australia aims to achieve net-zero emissions by 2050, and its building sector needs rapid change. The Nationwide House Energy Rating Scheme (NatHERS) is supported by the Australian Government to expand the current building envelope thermal performance energy star rating to a whole-of-home (WoH) energy rating. The NatHERS Administrator supports CSIRO to develop a benchmark WoH energy rating tool for new and existing housing, respectively. The tool for new housing was released in June 2023. This study presents the tool development for Australian existing housing. A case study was conducted using the tool for the eight capital cities of Australian states and territories. It shows that with a detached house built in the 1900s being updated to six or more stars and replacing old equipment and appliances with high-energy-efficient ones, more than 50% of energy can be saved in all the eight cities. To be zero-energy (carbon) housing, 5 kW solar PV needs be installed in Darwin and Hobart, 4 kW in Melbourne and Canberra, 3.5 kW in Adelaide and Sydney, and 3 kW in Brisbane and Perth. It demonstrates that this tool can be used for housing retrofitting to be low/zero-carbon emissions and low operational cost.