The high energy use of hospitals and healthcare facilities globally contributes to greenhouse gas emissions. At the same time, a large percentage of this energy use is attributed to space heating, cooling and ventilation, and is hence correlated to the climate. While the energy performance of Australian hospitals at the design stage is evaluated using historical weather data, the impact of the warming climate on Australian hospitals into the future remains unknown. The research question addressed is: What is the impact of future climates on the energy use of Australian hospitals built with the current design conditions? Two archetype hospital models were developed (a small single-story healthcare facility and a large multi-story hospital). DesignBuilder was used to simulate the performance of these models in 10 locations, ranging from the tropics to cool temperate regions in Australia. Current (1990–2015) and future climate files (2030, 2050, 2070 and 2090) were used. The results show that with the warming climate, the heating demand decreased, while the cooling demand increased for both hospital models for all sites. Cooling dominated climates, such as Darwin and Brisbane, were significantly impacted by the changing climates due to a substantial increase in cooling energy use. Heating based climates, such as Hobart and Canberra, resulted in an overall small reduction in total building energy use. In addition, the single-story facility was more impacted by the change in climate (in terms of energy use intensity) than the multi-story facility. The study highlights the importance of future climate files in building simulation and decarbonization planning.