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 (0.92°C), more humidity (0.35g/kg) and less GHI and DNI (8.15 Wh/m2 and 18.38Wh/m2), while winter months (June-August) had much higher temperatures (2.14°C), high humidity (0.72g/kg), and less GHI and DNI (12.69 Wh/m2 and 37.11Wh/m2). Also, overall, 2024 shows near 0 precipitation from January to April and much higher precipitation in August and October (96.6mm and 43mm higher). However, total precipitation is similar to 2023.
Comparing 1990-2004 with 2010-2024 showed an increase in Perth’s mean temperature of 0.60°C (3.33%), a slight decrease in moisture of 0.34%, and a significant increase in wind speed of 16.38%. GHI and DNI had high increases of 2.86% and 1.18% respectively. Meanwhile, comparing 2005-2019 with 2010-2024 showed a decrease in the mean temperature of 0.31°C (1.66%), a decrease in moisture of 0.42%, an increase in wind speed of 1.03%, and an increase in GHI and DNI of 1.11% and 0.53% respectively. Compared to the periods 1990–2004 and 2005–2019, the increase in mean temperature, GHI, and DNI, along with lower precipitation and similar humidity in 2010–2024, contributed to a warmer Perth.
Average precipitation in 2010-2024 was 11.19% lower than in 1990-2004, and 1.63% lower than the 2005-2019 period. When comparing monthly averages, overall the 2010-2024 period had similar precipitation to 1990-2004 and 2005-2019 except for May to July in 1990-2004.
Compared to the ISMY period (1990–2015), the most recent 15 years (2010–2024) show notable climate changes: mean temperature increased by 0.32°C (1.74%), moisture decreased by 0.78%, and wind speed grew by 4.52%. Additionally, GHI and DNI increased by 2.75% and 3.58% respectively. Average precipitation also decreased by 9.58%. 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, as well as in the 15-year periods of 1990-2004, 2005-2019 and 2010-2024, while heating energy consumption had decreasing trends for the supermarket in all periods. For the 3-storey and 10-storey offices, heating energy consumption increased from 1990-2004 and 1990-2015 but decreased from 2005-2019 and 2010-2024. 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.