Home is where the energy modelling heart is

By  Ruth Dawkins ,  Anthony Wright 13 November 2025 7 min read

For more than 80 years, CSIRO’s scientists have been studying how Australian homes use and lose energy – and how to make them perform better. What began as post-war experiments in building physics has grown into a national capability underpinning Australia’s energy standards, policies and technologies.

Today, almost 90 per cent of new Australian homes – about $50 billion in annual construction – depend on CSIRO’s modelling tools. But as the nation’s housing stock, climate and technology have changed, so too has the science behind them.

Anthony Wright leads the Energy Performance Group in our Energy Systems research program. 

“The environment changes in all sorts of ways, and we adapt – but we also change the environment in return. That’s the story of this energy rating work. It’s always evolving in response to how Australians live,” said Anthony.

From early experiments to national standards

Australia’s first scientific studies into the relationship between buildings and climate began in 1944, when the Commonwealth Experimental Building Station and the CSIRO Division of Building Research (initially called the Building Research Laboratory) were established.

By the early 1950s, CSIRO had created mathematical models capable of predicting indoor temperatures for a single room. Through the 1960s and 70s, these evolved into full-building simulations. Then, in 1998, CSIRO scientists combined decades of research into the Chenath Engine: a program that would become the backbone of the Nationwide House Energy Rating Scheme (NatHERS).

Over the decades, the modelling tools have moved from hand-written algorithms, punch cards and Fortran code to cloud computing, big data and now artificial intelligence.

Yet even with so much technical change, traces of the past remain woven through the science as reminders of how long this work has been part of Australia’s story.

According to Anthony, some fascinating quirks remain embedded in the models themselves.

One long-standing assumption, a significant heat load between 4pm and 6pm, when “children are home and a meal is being prepared”, implies that for two hours every day someone is “frying, grilling, roasting or baking”.

“It’s extraordinary,” Anthony said. “You can see how social norms and biases from the 1940s found their way into the software assumptions and must be constantly revisited and questioned to ensure the modelling reflects modern life.”

Despite the transformations in technology, the purpose of CSIRO’s work in this area remains constant: to provide trusted, evidence-based data and modelling tools for regulators, industry and households.

That consistency has delivered tangible results, with an independent impact assessment in 2024 estimating that CSIRO’s residential energy modelling tools have delivered $1.72 billion in net benefits, returning $69 for every $1 invested.

The evolution of Australian homes

Understanding how our homes have changed is also key to understanding why CSIRO’s research keeps evolving.

“In the Victorian era of the late 1800s/early 1900s, houses were built from heavy materials like solid brick and heated with open fires,” Anthony said.

“Those homes were leaky by design – you needed airflow to feed the fire. The bricks absorbed the heat and radiated it back, so people stayed warm.”

After World War II, construction methods changed rapidly to meet demand from returning service members and the baby boom. 

“Engineering practices shifted. We got lighter materials, bigger windows and houses that could be built quickly and cheaply,” he said.

By the 1960s and 70s, cheap energy and new technologies encouraged Australians to build larger, less efficient homes. “No one thought about running out of gas or the cost of energy use,” Anthony said.

“You could heat your home easily – so design stopped being efficient.”

From the 1980s onward, awareness grew about sustainability and insulation, leading to Australia’s first energy standards in 1998.

At the same time, air-conditioning became ubiquitous. CSIRO’s models and analysis supported the introduction of the 5-, 6- and now 7-star energy ratings in the National Construction Code.

Each step represented not just a change in regulation, but an evolution in how science, industry and society viewed the role of housing in comfort, health and emissions.

Current challenges

Today, residential buildings account for around 24 per cent of Australia’s electricity use and more than 10 per cent of total carbon emissions. Millions of older homes, built before any energy standards existed, continue to use more energy than necessary and drive up both household bills and electricity infrastructure costs.

Anthony and his team are tackling this challenge head-on, not only by improving the science, but by creating broader demand for energy-efficient housing. Building on decades of CSIRO research, their mission is to make home performance visible, measurable and actionable for everyone, from homeowners to financiers.

While heat-flow modelling remains at the core of the work, CSIRO’s expertise now spans far beyond the physics of buildings. The organisation brings together building scientists, social researchers and data specialists to understand how homes perform, how people live in them, and how to communicate that knowledge in ways that drive change.

Recent advances include updating energy modelling tools to harness AI and cloud computing; developing models that allow banks to estimate the energy performance of mortgage portfolios; expanding the Nationwide House Energy Rating Scheme to cover existing dwellings; creating the public Australian Housing Data portal to share information on housing performance; and applying social science to help homeowners to act on efficiency – including through the Banksia Award-winning Renovate or Rebuild television program.

“We realised a long time ago that part of our role isn’t just to provide energy rating tools, but to explain the science behind them and the benefits of energy efficient housing,” said Anthony.

“We’re trying to get the data out there to the people who can act on it. Bankers, real estate agents, landlords, homeowners… if we have a much broader section of the population who can see and understand the data, they can make better decisions about improving performance.”

Looking ahead: resilience and net-zero ambitions

As Australia moves toward a net-zero economy, housing research is entering a new phase. Climate change, affordability and resilience are now as central to the science as efficiency once was.

The Productivity Commission’s Investing in Cheaper, Cleaner Energy and the Net Zero Transformation interim report, released in 2025, calls for a national resilience rating system for housing – a concept that builds directly on the success of NatHERS.

“Until now, energy standards have focused on mitigation – reducing emissions and driving down household bills,” Anthony said. “But resilience is the next big challenge. We need homes that can handle heatwaves, floods and future climate extremes.”

CSIRO’s current research priorities reflect that shift. 

Over the next three years, the team aims to complete and publish Australia’s first indoor thermal comfort standards; develop grid-interaction metrics; test modelling assumptions about home energy use (e.g. work-from-home impacts and growth in the apartment market as Australia moves to increase housing density); expand data provision and make a national building stock model available to other researchers.

“Over a longer horizon, we hope our research will enable the linking of building standards to grid planning; better health outcomes for vulnerable people and support homeowners to build, buy, rent, retrofit and sell energy efficient homes,” said Anthony.

Building for the future

Australia’s housing research story is one of adaptation – scientific, social and environmental. From a handful of building physicists in the 1950s to today’s multidisciplinary teams of data scientists, social researchers and engineers, CSIRO’s work continues to evolve with the nation it serves.

“Residential building modelling might sound like a niche area of research,” said Anthony.

“But as soon as you start talking about housing, you’re talking about health, energy, the environment, finance and planning. It touches everything.”

Eighty years on, CSIRO’s housing science remains at the heart of how Australia builds, and will continue to shape our homes, communities and energy systems of the future.

Related stories:

• How do I use air conditioning efficiently? Is it better to blast it briefly throughout the day, or just leave it on?
• Sealing the comfort of our new homes
• Better by design: Culture at the heart of remote housing in the Northern Territory