As part of the ongoing investigation into our evolving climate, we routinely process and analyse meteorological data from successive years, conducting comparative assessments to reveal emerging trends and patterns.
Our previous temporal analyses only focused on examining variations in various weather elements with the results of EnergyPlus simulations of the three archetypes used in our Weather and Energy Index (EWEI), specifically targeting HVAC systems and heating and cooling dynamics within buildings. We have added the results of System Advisor Model (SAM) photovoltaic (PV) system simulations to enhance the comprehensiveness of our investigation up to 2023. The analysis for other capital cities can be viewed here.
Now, we are extending our previous temporal analysis to 2024 for all eight capital cities, so readers will soon be able to access our recent analysis on our blog.
For the analysis of weather elements, we examined the temporal variations in dry bulb temperature, humidity, wind speed, global horizontal irradiation (GHI), direct normal irradiation (DNI), and average precipitation. The analysis involved averaging these elements over three 15-year periods—1990-2004, 2005-2019, and the latest 15-year period from 2010 to 2024—and then comparing the results. A comparison between data from the latest 15 years, the data corresponding to the years and months specified in Industry Standard Meteorological Year (ISMY) files, and the data exclusively from 2024 was also undertaken. ISMYs were originally developed for application in house energy rating software used in NatHERS and derive from historical Bureau of Meteorology (BOM) weather data spanning from 1990 to 2015. Over time, they have become the industry’s de facto standard. It is therefore important to compare against ISMY data, as it provides a reference to gauge alignment with established benchmarks and understand the significance of temporal variations in weather elements.
First of all, we compared 2024 weather data with 2023 data. Overall, summer months (December-February) had higher temperatures (0.1°C) and humidity (0.19g/kg) while less GHI and DNI (8.52 Wh/m2 and 12.94Wh/m2). Winter months (June-August) had lower temperatures (0.44°C), lower humidity (0.25g/kg) and higher GHI and DNI (1.61 Wh/m2 and 7.43Wh/m2). In addition, 2024 had nearly 45.7% higher precipitation than 2023. Especially, January, March and November 2024 had higher precipitation than 2023 (253.4mm in January, 240.8mm in March and 147.4mm in November).
Comparing 1990-2004 with 2010-2024 showed an increase in Darwin’s mean temperature of 0.34°C (1.26%), an increase in moisture of 1.5%, and a significant increase in wind speed of 13.71%. GHI and DNI had decreases of 3.88% and 11.52% respectively. Meanwhile, comparing 2005-2019 with 2010-2024 showed an increase in the mean temperature of 0.21°C (0.78%), an increase in moisture of 1.67%, a decrease in wind speed of 5.13%, and a decrease in GHI and DNI of 2.65% and 5.52% respectively.
Average precipitation in 2010-2024 was 1.90% lower than in 1990-2004, and 0.64% higher than the 2005-2019 period. When comparing monthly averages, precipitation 2010-2024 for every month was generally similar to 2005-2019 and 1990-2004.
Compared to the ISMY period (1990–2015), the most recent 15 years (2010–2024) show notable climate changes: mean temperature increased by 0.23°C (0.84%), moisture rose by 2.02%, and wind speed decreased by 0.77%. Additionally, GHI and DNI decreased by 4.02% and 10.47% respectively. In addition, average precipitation decreased by 1.35% (2.06mm). These shifts highlight distinct climatic trends between the two periods.
The annual trends of energy consumption reveal intriguing patterns across various building archetypes. All archetypes had increasing trends for cooling energy consumption from 1990-2024, 2005-2019 and 2010-2024 while decreasing in 1990-2004 and 1990-2015. These trends are indicative of a changed climate and highlight the importance of using relevant climate files from the more recent 2010-2024 period in building energy simulations rather than the older ISMY data.