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 Adelaide. The findings for Brisbane were previously discussed in the February 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 Adelaide’s mean temperature of 0.54°C, a decrease to moisture of 0.78%, and a decrease in wind speed of 2.43%. GHI had an increase of 2.39%, while DNI had a smaller decrease of 0.86%. Meanwhile, comparing 2005-2019 with 2009-2023 showed a decrease in the mean temperature of 0.13°C, an increase to moisture of 1.29%, a comparably decrease in wind speed of 0.01%, and a decrease in GHI and DNI of 0.86% and 3.45%, respectively. The decline in mean temperature, GHI, and DNI for 2005-2019 vs 2009-2023 is likely a result of 2020-2022 experiencing comparatively lower annual average dry bulb temperatures, GHI, and DNI when compared to other years.

Total precipitation in 2009-2023 averaged 5.66% less than in 1990-2004. However, compared to the 2005-2019 period, it saw a dramatic 4.97% increase.

Annual total HVAC energy consumption shows interesting trends for all archetypes’ the 1990-2023, 1990-2004 and 2005-2019 periods show increased trends, while the 2009-2023 period has decreased trends. If we take a look at this more carefully, for all archetypes, the annual heating energy consumption trend from 1990 to 2004 period has an upward trend while 2005-2019,2009-2023 and 1990-2023 have downward trends and the cooling energy consumption trend is identical to the total HVAC energy consumption. Thus, both Heating and Cooling energy consumption have downtrends from 2009 to 2023 for all archetypes. This indicates the notable differences in temperature within the recent 2009-2023 period compared to older 15-year periods, and ISMY.

Exemplary’s Executive Director, Trevor Lee, attended a Brisbane tour of developments in this field on 27 March. The tour was run by the Australian Association for Energy Productivity (A2EP) which Exemplary joined late last year.

On the following day, he met with like minded investors in Byron Bay, NSW, in the morning and then visited the laboratory premises of UAG Bio Nutrients in Alstonville and the newly-opened gas-fired Beacon Laundry (initiated by Whitebox Enterprises) in Bangalow before finishing the day in a meeting nearby with Negawatt Projects who actively promote heat pump technology in aquatic centres and commercial laundries for the displacement of gas as their predominant heat source.

Trevor sees excellent scope for involvement in such activities although perhaps in the role of certified measurement and verification professionals (CMVP) rather than direct participants in this field.

Several groups are studying this issue and making recommendations to Australian governments and the Building Codes Board (ABCB). We have reported earlier on the work of Dr Anir Upadhyay at UNSW in association with Western Sydney Regional Organisation of Councils (WSROC) in this area using historic and ersatz future data supplied by Exemplary (A higher NatHERS star rating: Is it the holy grail of low energy and heat resilient residential buildings?).

The imminent issue of “Renew” magazine will include a synopsis of the report to be published around the same time by Sweltering Cities and Renew with the support of Energy Consumers Australia (ECA) analysing how changing climate conditions impact Australian home energy efficiency.

“Australian building standards require homes to meet energy efficiency standards (NatHERS). These NatHERS ratings measure how much energy is needed to heat and cool homes in a range of climate zones, setting limits for heating and cooling loads to achieve star ratings. The climate zones are designed using existing weather data: until 2022 these were based on weather data from 1970-2005; from 2022 the data is from 1990-2015.”

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 Brisbane. The findings for Sydney and Melbourne were previously discussed in the 2023 December and 2024 January 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, moisture, 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 corrected ISMY data, as it provides a reference to gauge alignment with established benchmarks and understand the significance of temporal variations in weather elements. It is essential to use corrected ISMY data due to the gross timing errors in the misleading EPW versions provide free by CSIRO: see here for details.”

Comparing 1990-2004 with 2009-2023 showed an increase in Brisbane’s mean temperature of 0.35°C, an increase to moisture of 8.17%, and an increase in wind speed of 5.44%. GHI had a decrease of 2.94%, while DNI had a bigger decrease of 9.14%. Meanwhile, comparing 2005-2019 with 2009-2023 showed a decrease in the mean temperature of 0.06°C, an increase to moisture of 0.64%, a more significant decrease in wind speed of 1.07%, and a decrease in GHI and DNI of 1.25% and 2.23%, respectively. The small increase in mean temperature and decline in GHI, and DNI for 2005-2019 vs 2009-2023 is likely a result of 2020-2022 experiencing slightly higher annual average dry bulb temperatures while lower GHI, and DNI when compared to other years.

Total precipitation in 2009-2023 averaged 7.96% higher than in 1990-2004 and compared to the 2005-2019 period, it saw a dramatic 11.61% increase.

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 without 1990-2004. These trends are indicative of a 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.