Author: HongGic Oh

Exemplary Weather and Energy (EWE) Index September 2026

The Exemplary Real Time Year weather files (RTYs), current Reference Meteorological Year files (RMYs) and Ersatz Future Meteorological Years (EFMYs) used for these monthly simulations are available for purchase. This will allow clients to simulate their own designs for energy budgeting and monitoring rather than rely on analogy with the performance of these archetypical buildings and systems. Especially in mild months, small differences in energy consumptions can result in large percentage differences. Solar irradiation data courtesy of Solcast.

Archetypical buildings and systems

10-storey office

3-storey office

Supermarket

5 kW domestic
PV system

Get the Best out of our Interactive Features

This monthly report has been interactive since April 2023.  Once you have scrolled to your city of interest, check out those interactive features and how they work.  Click here to read about the introduction.

  • 1. Choose the energy or peak demand graph to best match your building or system of interest.
  • 2. Choose the weather element graph to best match the sensitivity of your building or system of interest.
  • 3. Mix and match to learn about their relative importance or sensitivity

All values are % higher/lower energy demand/output relative to climatically typical weather.

Especially during the mild seasons, large % changes can occur from small absolute differences. RTYs are available for purchase for your own simulations.

ADELAIDE

Energy Index (%)

The solar PV simulation output was 2.7% lower than the long-term average. The heating peak loads were lower than the long-term average for the 3-storey office, 10-storey office and supermarket, by 24.9%, 22.9% and 17.9%, respectively.  It should be noted that peak load results are highly sensitive to the particular building and HVAC design and settings – it is more appropriate to evaluate those results from the bespoke building model (digital twin) using our RTY data.

Adelaide experienced slightly warmer temperatures and lower relative humidity in September. Both GHI and wind speeds were lower than the long-term averages.

Weather Index



BRISBANE

Energy Index (%)

The solar PV simulation output was 6.5% lower than the long-term average. The heating peak loads were lower than the long-term average for the 3-storey office, 10-storey office and supermarket, by 34.2%, 13.6% and 40.1%, respectively. It should be noted that peak load results are highly sensitive to the particular building and HVAC design and settings – it is more appropriate to evaluate those results from the bespoke building model (digital twin) using our RTY data.

Brisbane experienced similar temperatures and higher relative humidity than the long-term average in September, while GHI and wind speeds were lower than the long-term average.

Weather Index



CANBERRA

Energy Index (%)

The solar PV simulation output was 2.8% higher than the long-term average. The heating peak loads were lower than the long-term average for the 3-storey office, 10-storey office and supermarket, by 14.5%, 18.5% and 8.1%, respectively.  It should be noted that peak load results are highly sensitive to the particular building and HVAC design and settings – it is more appropriate to evaluate those results from the bespoke building model (digital twin) using our RTY data.

Canberra experienced substantially warmer temperatures in September, while relative humidity was slightly higher than the long-term average. GHI was higher in the afternoon while wind speeds were lower than the long-term average most of the time.

Weather Index



DARWIN

Energy Index (%)

The solar PV simulation output was 8.8% lower than the long-term average. The cooling peak loads were lower than the long-term average for the 3-storey office, 10-storey office and supermarket, by 2.0%, 3.6% and 1.5%, respectively. It should be noted that peak load results are highly sensitive to the particular building and HVAC design and settings – it is more appropriate to evaluate those results from the bespoke building model (digital twin) using our RTY data.

Darwin experienced slightly warmer temperatures and higher relative humidity than the long-term average in September. GHI was lower than the long-term average, while wind speeds are higher in the morning and remained similar for the rest of the day.

Weather Index



HOBART

Energy Index (%)

The solar PV simulation output was 8.1% higher than the long-term average. The heating peak loads were lower than the long-term average for the 3-storey office, 10-storey office and supermarket, by 44.6%, 48.5% and 35.0%, respectively. It should be noted that peak load results are highly sensitive to the particular building and HVAC design and settings – it is more appropriate to evaluate those results from the bespoke building model (digital twin) using our RTY data.

Hobart experienced much warmer temperatures, but relative humidity is substantially lower than the long-term average in September. GHI was slightly higher and wind speeds were higher than the long-term average.

Weather Index



MELBOURNE

Energy Index (%)

The solar PV simulation output was 12.6% higher than the long-term average. The heating peak loads were lower than the long-term average for the 3-storey office, 10-storey office and supermarket, by 28.0%, 40.3% and 31.3%, respectively. It should be noted that peak load results are highly sensitive to the particular building and HVAC design and settings -it is more appropriate to evaluate those results from the bespoke building model (digital twin) using our RTY data.

Melbourne experienced warmer temperatures and higher relative humidity in September. GHI was much higher than the long-term average.

Weather Index



PERTH

Energy Index (%)

The solar PV simulation output was 5.0% lower than the long-term average. The heating peak loads were lower than the long-term average for the 3-storey office, 10-storey office and supermarket, by 77.7%, 77.7% and 60.8%, respectively. It should be noted that peak load results are highly sensitive to the particular building and HVAC design and settings – it is more appropriate to evaluate those results from the bespoke building model (digital twin) using our RTY data.

Perth experienced substantially warmer temperatures than the long-term average in September. GHI was lower in the morning while slightly higher in the afternoon. The wind speeds were close to average during most of the day, with the exception of the evening.

Weather Index



SYDNEY

Energy Index (%)

The solar PV simulation output was 2.8% lower than the long-term average. The heating peak loads were lower than the long-term average for the 3-storey office, the 10-storey office and the supermarket by 21.2%, 37.8% and 25.6%, respectively. It should be noted that peak load results are highly sensitive to the particular building and HVAC design and settings – it is more appropriate to evaluate those results from the bespoke building model (digital twin) using our RTY data.

Sydney experienced much warmer temperatures and similar relative humidity in September compared with the long-term average. GHI remained close to the long-term average while wind speeds were higher than the long-term average.

Weather Index



Exemplary Weather and Energy (EWE) Index August 2026

The Exemplary Real Time Year weather files (RTYs), current Reference Meteorological Year files (RMYs) and Ersatz Future Meteorological Years (EFMYs) used for these monthly simulations are available for purchase. This will allow clients to simulate their own designs for energy budgeting and monitoring rather than rely on analogy with the performance of these archetypical buildings and systems. Especially in mild months, small differences in energy consumptions can result in large percentage differences. Solar irradiation data courtesy of Solcast.

Archetypical buildings and systems

10-storey office

3-storey office

Supermarket

5 kW domestic
PV system

Get the Best out of our Interactive Features

This monthly report has been interactive since April 2023.  Once you have scrolled to your city of interest, check out those interactive features and how they work.  Click here to read about the introduction.

  • 1. Choose the energy or peak demand graph to best match your building or system of interest.
  • 2. Choose the weather element graph to best match the sensitivity of your building or system of interest.
  • 3. Mix and match to learn about their relative importance or sensitivity

All values are % higher/lower energy demand/output relative to climatically typical weather.

Especially during the mild seasons, large % changes can occur from small absolute differences. RTYs are available for purchase for your own simulations.

ADELAIDE

Energy Index (%)

The solar PV simulation output was 10.4% lower than the long-term average. The heating peak loads were lower than the long-term average for the 3-storey office, 10-storey office and supermarket, by 31.3%, 27.3% and 25.6%, respectively.  It should be noted that peak load results are highly sensitive to the particular building and HVAC design and settings – it is more appropriate to evaluate those results from the bespoke building model (digital twin) using our RTY data.

Adelaide experienced slightly warmer temperatures and higher relative humidity in August, while GHI and wind speeds were lower than the long-term averages.

Weather Index



BRISBANE

Energy Index (%)

The solar PV simulation output was 12.5% lower than the long-term average. The heating peak loads were lower than the long-term average for the 3-storey office, 10-storey office and supermarket, by 26.4%, 21.0% and 33.9%, respectively. It should be noted that peak load results are highly sensitive to the particular building and HVAC design and settings – it is more appropriate to evaluate those results from the bespoke building model (digital twin) using our RTY data.

Brisbane experienced temperatures similar to the long-term average during the daytime in August, but higher temperatures from the evening through to the morning. Relative humidity was much higher, while GHI was considerably lower. Wind speeds were below the long-term average during the daytime but higher during other periods.

Weather Index



CANBERRA

Energy Index (%)

The solar PV simulation output was 2.0% lower than the long-term average. The heating peak loads were higher than the long-term average for 3-storey office building and 10-storey office building by 8.1% and 8.9% while supermarket is slightly lower by 0.2%.  It should be noted that peak load results are highly sensitive to the particular building and HVAC design and settings – it is more appropriate to evaluate those results from the bespoke building model (digital twin) using our RTY data.

Canberra experienced slightly warmer daytime temperatures in August, while relative humidity was substantially higher throughout the day compared with the long-term average. GHI was similar to the long-term average, while wind speeds were generally lower.

Weather Index



DARWIN

Energy Index (%)

The solar PV simulation output was 7.2% lower than the long-term average. The cooling peak loads were higher than the long-term average for the 3-storey office building and 10-storey office building by 9.9% and 10.6% while supermarket is slightly lower by 0.1%. It should be noted that peak load results are highly sensitive to the particular building and HVAC design and settings – it is more appropriate to evaluate those results from the bespoke building model (digital twin) using our RTY data.

Darwin experienced warmer temperatures than the long-term average in August, along with higher relative humidity. GHI and wind speeds were below the long-term average for most of the day.

Weather Index



HOBART

Energy Index (%)

The solar PV simulation output was 0.8% higher than the long-term average. The heating peak loads were slightly higher than the long-term average for 3-storey office building and 10-storey office building by 3.4% and 1.6% while supermarket is lower by 12.9%. It should be noted that peak load results are highly sensitive to the particular building and HVAC design and settings – it is more appropriate to evaluate those results from the bespoke building model (digital twin) using our RTY data.

Hobart experienced warmer temperatures and similar humidity levels in August compared with the long-term average. GHI was much higher while wind speeds were lower than the long-term average.

Weather Index



MELBOURNE

Energy Index (%)

The solar PV simulation output was 9.6% lower than the long-term average. The heating peak loads were lower than the long-term average for 3-storey office building and supermarket by 7.8% and 1.6% while 10-storey office building is higher by 22.1%. It should be noted that peak load results are highly sensitive to the particular building and HVAC design and settings -it is more appropriate to evaluate those results from the bespoke building model (digital twin) using our RTY data.

Melbourne experienced warmer daytime temperatures and substantially higher relative humidity in August compared with the long-term average, while GHI remained similar to the long-term average.

Weather Index



PERTH

Energy Index (%)

The solar PV simulation output was 5.1% higher than the long-term average. The heating peak loads were significantly higher than the long-term average for the 3-storey and 10-storey office buildings, by 67.0% and 71.0%, respectively, while the supermarket showed a smaller increase of 7.6%. It should be noted that peak load results are highly sensitive to the particular building and HVAC design and settings – it is more appropriate to evaluate those results from the bespoke building model (digital twin) using our RTY data.

Perth experienced slightly warmer temperatures than the long-term average in August, along with similar relative humidity. GHI was also similar to the long-term average, while wind speeds were lower than the long-term average from the afternoon through to the morning.

Weather Index



SYDNEY

Energy Index (%)

The solar PV simulation output was 7.0% lower than the long-term average. The heating peak loads were lower than the long-term average for the 3-storey office, the 10-storey office and the supermarket by 4.4%, 0.9% and 24.4%, respectively. It should be noted that peak load results are highly sensitive to the particular building and HVAC design and settings – it is more appropriate to evaluate those results from the bespoke building model (digital twin) using our RTY data.

Sydney experienced warmer temperatures and higher relative humidity in August compared with the long-term average. Both GHI and wind speeds were lower than the long-term average.

Weather Index



Exemplary Weather and Energy (EWE) Index July 2026

The Exemplary Real Time Year weather files (RTYs), current Reference Meteorological Year files (RMYs) and Ersatz Future Meteorological Years (EFMYs) used for these monthly simulations are available for purchase. This will allow clients to simulate their own designs for energy budgeting and monitoring rather than rely on analogy with the performance of these archetypical buildings and systems. Especially in mild months, small differences in energy consumptions can result in large percentage differences. Solar irradiation data courtesy of Solcast.

Archetypical buildings and systems

10-storey office

3-storey office

Supermarket

5 kW domestic
PV system

Get the Best out of our Interactive Features

This monthly report has been interactive since April 2023.  Once you have scrolled to your city of interest, check out those interactive features and how they work.  Click here to read about the introduction.

  • 1. Choose the energy or peak demand graph to best match your building or system of interest.
  • 2. Choose the weather element graph to best match the sensitivity of your building or system of interest.
  • 3. Mix and match to learn about their relative importance or sensitivity

All values are % higher/lower energy demand/output relative to climatically typical weather.

Especially during the mild seasons, large % changes can occur from small absolute differences. RTYs are available for purchase for your own simulations.

ADELAIDE

Energy Index (%)

The solar PV simulation output was 3.9% lower than the long-term average. The heating peak load was lower than the long-term average for 3-storey office building and supermarket by 1.2% and 18.0% while 10-storey office building is slightly higher by 3.1%.  It should be noted that peak load results are highly sensitive to the particular building and HVAC design and settings – it is more appropriate to evaluate those results from the bespoke building model (digital twin) using our RTY data.

Adelaide experienced temperatures in July that were similar to the long-term average, along with higher daytime relative humidity. GHI was slightly below the long-term average before 2 pm and slightly above it between 2 pm and 6 pm. Wind speeds were lower during the daytime and higher during the remaining hours.

Weather Index



BRISBANE

Energy Index (%)

The solar PV simulation output was 8.3% lower than the long-term average. The heating peak load was much lower than the long-term average for 3-storey office building, 10-storey office building and supermarket, by 46.0%, 49.5% and 28.8%, respectively. It should be noted that peak load results are highly sensitive to the particular building and HVAC design and settings – it is more appropriate to evaluate those results from the bespoke building model (digital twin) using our RTY data.

Brisbane experienced warmer temperatures in July compared with the long-term average, while relative humidity was considerably higher. GHI and wind speeds were both below the long-term average.

Weather Index



CANBERRA

Energy Index (%)

The solar PV simulation output was 15.2% higher than the long-term average. The heating peak load was lower than the long-term average for the 3-storey office, 10-storey office and supermarket, by 21.7%, 19.2% and 0.2%, respectively.   It should be noted that peak load results are highly sensitive to the particular building and HVAC design and settings – it is more appropriate to evaluate those results from the bespoke building model (digital twin) using our RTY data.

Canberra experienced warmer daytime temperatures in July, while relative humidity was higher in the early morning but slightly lower during the daytime compared with the long-term average. GHI was much higher than the long-term average, while wind speeds were generally higher.

Weather Index



DARWIN

Energy Index (%)

The solar PV simulation output was 6.5% lower than the long-term average. The cooling peak load was lower than the long-term average for the 3-storey office building and 10-storey office building by 3.3% and 2.9% while supermarket is slightly higher by 1.5%. It should be noted that peak load results are highly sensitive to the particular building and HVAC design and settings – it is more appropriate to evaluate those results from the bespoke building model (digital twin) using our RTY data.

Darwin experienced similar temperatures to the long-term average in July, along with higher relative humidity. GHI was below average, while wind speeds were broadly similar to the long-term mean for most of the day.

Weather Index



HOBART

Energy Index (%)

The solar PV simulation output was 10.5% lower than the long-term average. The heating peak load was slightly lower than the long-term average for 3-storey office building and 10-storey office building by 0.9% and 0.5% while supermarket is slightly higher by 4.3%. It should be noted that peak load results are highly sensitive to the particular building and HVAC design and settings – it is more appropriate to evaluate those results from the bespoke building model (digital twin) using our RTY data.

Hobart experienced slightly warmer temperatures and similar humidity levels in July compared with the long-term average. GHI and wind speeds were also similar to the long-term average.

Weather Index



MELBOURNE

Energy Index (%)

The solar PV simulation output was 0.9% lower than the long-term average. The heating peak load was significantly higher than the long-term average for the 3-storey office building, the 10-storey office building and supermarket by 84.4% and 79.0% and 15.2% respectively. It should be noted that peak load results are highly sensitive to the particular building and HVAC design and settings -it is more appropriate to evaluate those results from the bespoke building model (digital twin) using our RTY data.

Melbourne experienced similar temperatures and higher relative humidity in July compared with the long-term average, while GHI was similar to the long-term average.

Weather Index



PERTH

Energy Index (%)

The solar PV simulation output was 12.6% higher than the long-term average. The heating peak load was significantly lower than the long-term average for the 3-storey office building and 10-storey office building and the supermarket by 51.2%, 58.6% and 8.3% respectively. It should be noted that peak load results are highly sensitive to the particular building and HVAC design and settings – it is more appropriate to evaluate those results from the bespoke building model (digital twin) using our RTY data.

Perth experienced much warmer daytime temperatures than the long-term average in July, along with similar relative humidity. GHI was much higher than the long-term average, while wind speeds were lower than the long-term average for the whole day.

Weather Index



SYDNEY

Energy Index (%)

The solar PV simulation output was 1.8% higher than the long-term average. The heating peak load was lower than the long-term average for the 3-storey office, the 10-storey office and the supermarket by 31.3%, 37.0% and 31.8%, respectively. It should be noted that peak load results are highly sensitive to the particular building and HVAC design and settings – it is more appropriate to evaluate those results from the bespoke building model (digital twin) using our RTY data.

Sydney experienced slightly warmer temperatures and similar relative humidity in July compared with the long-term average. Both GHI and wind speeds were higher than the long-term average.

Weather Index



Home Energy Models Validated Against Real Bills

Dayne Tompson

energyFit’s home energy models are validating at exceptional absolute accuracy against metered consumption, and are now being tested across six additional climate zones. This article sets out the evidence, and issues an open call to academics who would like to be involved in the research.

The gap between modelled and metered energy use is a stubborn problem in residential building science. Design-stage predictions routinely diverge from what a household actually pays, and closing that divergence is what allows retrofit and upgrade advice to be relied upon. energyFit, developed in the ACT since 2016, was built to close it.

A Digital Twin of the Actual Home

energyFit constructs a calibrated digital twin of the specific dwelling, combining LiDAR capture with EnergyPlus simulation. EnergyPlus is embedded as the thermal core, with energyFit’s engine running over the top to model occupant behaviour, generation and storage, and the full appliance load, thermal and non-thermal alike. The output is a dollar-denominated upgrade roadmap: what each intervention costs, what it saves, and in what order to do it where household budgets cannot action all advantageous changes promptly.

Validated Accuracy

Against metered household consumption in the ACT, energyFit has validated at 93% absolute accuracy for general electricity use, 96.4% for gas, and 98.3% for hot water. These are absolute figures using standard climate files – higher accuracy is expected using Real-Time Year actual weather data directly coinciding in time with the metered consumption data and is currently being tested. Overestimates and underestimates are not netted against one another, so the results are not flattered by errors in opposite directions cancelling out. For work that has to hold up against a real electricity and gas bill, that is an exceptional result.

Six NCC Climate Zones

Accuracy in a single climate is necessary but not sufficient. The method is now being tested across all six NCC climate zones in NSW, to establish whether ACT-level accuracy holds across a wider range of thermal conditions, building stock, and household behaviour. That trial is the mechanism through which the evidence is being built.

Reducing the Cost of a Low-Bill Home

Delivering upgrades at scale has generally meant standardised packages: the same insulation, the same heat pump, the same solar specification across many homes. That approach is administratively efficient, but the marginal saving from any measure depends on the specific building. A retrofit that pays for itself in one dwelling can return very little in the one next door.

Because energyFit models each home individually, it can find the least-cost path to a target bill for that home, and identify which measures will do the work. The cost of delivering a low-bill home falls, not because ambition is lowered, but because capital goes where the model shows it will earn a higher return. For a scheme administrator, that means more low-bill homes per dollar of subsidy. The same applies even if the household is targeting a Net Zero Emissions outcome.

Call for Collaboration

The six-zone trial will generate an unusual quantity of matched modelled-and-metered data across diverse conditions. Researchers who would like to be involved are invited to make contact.

Collaboration would be especially valuable in thermal simulation validation, the economics of least-cost retrofit optimisation, behavioural questions around why households act on cost information, and the evaluation of information-barrier versus price-barrier segmentation in energy efficiency schemes.

  Expressions of interest can be directed to Dayne Thompson at dayne@sjtconsulting.com.au

Disclousre of Interest

Exemplary Investments has made a small hybrid-debt investment in this work; and Exemplary Energy will conduct a randomly selected blind re-simulation of a sample of homes to establish any enhancement of accuracy achieved by applying Real-Time Year weather data to the energyFit method.