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 (1.07°C), humidity (0.63g/kg), GHI and DNI (13.32 Wh/m2 and 33.63Wh/m2), while winter months (June-August) had lower temperatures (0.23°C), higher humidity (0.07g/kg), and less GHI and DNI (4.65 Wh/m2 and 4.197Wh/m2). Also, overall, 2024 had significantly less precipitation (51.46% lower) than 2023, particularly between February and May, when rainfall was minimal or absent.
Comparing 1990-2004 with 2010-2024 showed an increase in Adelaide’s mean temperature of 0.51°C (3.06%), a small decrease in moisture of 0.14%, and a decrease in wind speed of 3.32%. GHI and DNI had an increase of 2.47% and 0.11%, respectively. Meanwhile, comparing 2005-2019 with 2010-2024 showed a decrease in the mean temperature of 0.16°C (0.90%), an increase in moisture of 1.95%, a decrease in wind speed of 0.93%, and a decrease in GHI and DNI of 0.79% DNI and 3.69% respectively. The small decrease in mean temperature and increase in GHI for 2005-2019 vs 2010-2024 is likely a result of 2005-2019 experiencing comparatively higher annual average dry bulb temperatures and GHI when compared to other years.
Average precipitation in 2010-2024 was 8.43% lower than in 1990-2004, and 1.89% lower than the 2005-2019 period. When comparing monthly averages, precipitation from 2010 to 2024 was generally lower than from 2005 to 2019, except in January. It was also lower than from 1990 to 2015, except in January and July. These big differences among 1990-2004, 2005-2019 and 2010-2024 will affect building simulation model results for heating and cooling.
Compared to the ISMY period (1990–2015), the most recent 15 years (2010–2024) show notable climate changes: mean temperature increased by 0.24°C (1.43%), moisture rose by 1.36%, and wind speed decreased by 0.76%. Additionally, GHI and DNI increased by 0.04% and 4.09% respectively and average precipitation rose by 4.7% (1.93mm). 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, 1990-2004, 2005-2019, as well as in the 26-year period of 1990-2015 still in widespread use for building simulations despite the significantly warmer subsequent decade. However, an unexpected decreasing trend emerged in 2010–2024. In contrast, heating energy consumption followed an opposite pattern with decreasing trends for all archetypes in 1990-2024, 2005-2019, 1990-2015 and 2010-2024 periods, but increasing trends in 1990-2004. 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.