Development of an on-line Australian residential building stock model

The 11 million residential buildings in Australia are responsible for approximately 24% of the electricity use and 10% of the overall carbon emissions. To achieve Australia’s net zero target by 2050, around half of this residential building stock, especially older low energy efficient buildings, are expected to be retrofitted with energy-efficient measures. Under the Cooperative Research Center Program RACE for 2030 project “Energy Upgrades for Australian Homes”, an on-line Australian residential building stock model was developed to facilitate home retrofitting projects at different levels for various stakeholders.

The building stock model is based on 1 million real dwelling designs obtained via the NatHERS scheme from 2018 to 2022 across all Australian local climates, which covers around 90% of all the dwellings approved for building during the same period in Australia. First, individual building information such as the year built, building floor area, wall construction materials, and bedroom numbers for the 11 million residential buildings were obtained from real estate companies and Australian Bureau of Statistics. Second, the building leakage, building floor, ceiling, roof, and external wall insulation levels, window types, HVAC systems, and solar PV installation of the 1 million new dwelling designs were adjusted to represent dwellings built in any specific year as well as dwellings to be retrofitted via various options.

Thirdly, building simulations were carried out for these adjusted building designs and retrofit options for two different occupancies, i.e., a full day occupancy and a working family occupancy. Estimates of the energy use and carbon emission, indoor thermal comfort and overcooling/overheating risks under the current local climate and future climates in 2030 and 2050 were performed. By combining all the previous steps, the costs and savings in the energy use and carbon emissions, the payback periods, and the co-benefit cost savings due to the health improvement are estimated and predicted for individual housing types, from SA1 (Statistical Area Level 1), and local council level, to state and national levels under various retrofitting scenarios in present and future climates.

This on-line Australian residential building stock model is anticipated to be used by individual house owners to facilitate the uptake of cost effective retrofitting options; to help researchers to explore the potentials of various technological solutions; to assist local councils, state and federal governments to develop incentive policies and schemes for promoting retrofitting of the 5-6 million residential buildings constructed before the era of energy efficient regulations in Australia.