Examining Hobart’s Climate Trends: Implications for PV System and Building Performance

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. However, in this latest iteration, we have incorporated the results of EnergyPlus simulations, specifically targeting HVAC systems and heating and cooling dynamics within buildings. We have also added the results of System Advisor Model (SAM) photovoltaic (PV) system simulations to enhance the comprehensiveness of our investigation.

The most recent temporal analysis was carried out for all eight capital cities, though this issue of Exemplary Advances will focus on the city of Hobart. The findings for Darwin were previously discussed in the June issue of Exemplary Advances. The analysis for other capital cities can be viewed here.

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 total precipitation. The analysis involved averaging these elements over three 15-year periods—1990-2004, 2005-2019, and the latest 15-year period from 2009 to 2023—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 2023 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.

Comparing 1990-2004 with 2009-2023 showed an increase in Hobart’s mean temperature of 0.57°C, an increase in moisture of 2.40%, and a significant increase in wind speed of 9.45%. GHI had a decrease of 1.54%, and DNI had a significant decrease of 11.28%. Meanwhile, comparing 2005-2019 with 2009-2023 showed a decrease in the mean temperature of 0.09°C, an increase in moisture of 1.31%, a decrease in wind speed of 0.35%, and a decrease in GHI and DNI of 0.96% and 4.65%, respectively. The small increase in mean temperature and decrease for GHI and DNI for 2005-2019 vs 2009-2023 is likely a result of 2020-2023 experiencing comparatively higher annual average dry bulb temperatures and lower GHI and DNI when compared to other years.

Total precipitation in 2009-2023 averaged 3.04% higher than in 1990-2004, and 6.18% higher than the 2005-2019 period.

The annual trends of energy consumption reveal intriguing patterns across various building archetypes. All archetypes had increasing trends for cooling energy consumption from 1990 to 2023, as well as in the 15-year periods of 1990-2004, 2005-2019 and 2009-2023, while heating energy consumption had decreasing trends for all archetypes in all periods. These trends are indicative of warming climate, and highlight the importance of using relevant climate files from the more recent 2009-2023 period in building energy simulations rather than the older ISMY data.