by Kate Cranney, CSIRO

In the wise words of the great Aussie battler Darryl Kerrigan, your home is your castle. So how do we make sure that castle is as comfortable, energy efficient, sustainable, and economical as possible? For 60 years, a team of CSIRO researchers has been working on residential energy efficiency.

Anthony Wright, researcher and former building designer, heads up the 20-strong group, known as the Building Simulation Assessment and Communication team.

“We’re a multidisciplinary bunch: we have a full team of building physicists, social scientists, and data scientists,” said Mr Wright. “We’re trying to really tackle the housing energy efficiency question from every angle, simultaneously,” said Mr Wright.

The research is increasingly topical. Australian households are responsible for 11 per cent of our overall energy use and 12 per cent of total carbon emissions. With the number of dwellings in Australia expected to double by 2050, here is a sample of CSIRO residential energy efficiency science.

Modernising the tools behind energy rating systems

You’ve probably heard of Australia’s 10-star residential energy rating system. For more than 20 years, CSIRO has worked on the science and tools behind the Nationwide Housing Energy Rating Scheme (NatHERS). NatHERS began in 1993 and was adopted nationally in 2004.

NatHERS models the thermal performance of a home, based on design and materials. The star rating system helps homeowners, architects and builders compare the energy efficiency of designs, and informs prospective buyers.

Assessors input data from the house plans into the software: hundreds of factors like the local climate, orientation, construction, and design. The software then estimates the energy required to heat or cool the house and produces a star rating out of 10 and a certificate.

With so many different types of homes and climates around Australia, the software needs to be smart. NatHERS assessors use one of four accredited software tools, including the CSIRO-designed software, ‘AccuRate’.

“We provide the backbone infrastructure of the NatHERS tools. Now we’re modernising those tools; for instance, we’re moving AccuRate to the cloud, and making more options available to the private sector,” Mr Wright said.

The team is also working with private sector organisations to add appliances to the NatHERS calculations, allowing a ‘whole-of- house’ rating. And they’re developing the RapidRate AI that can very quickly, and accurately, generate energy ratings from just 12 simple inputs, which is especially useful for ‘volume builders’ who build lots of houses from fixed designs, and for the finance sector which needs large numbers of ratings for existing houses.

Unique insights from the Australian Housing Data Portal

We all love data, and since 2019, CSIRO has displayed data from NatHERS certificates on the Australian Housing Data portal. The portal lets users see trends in homes over time, and understand our progress towards energy-efficient, low-emission homes.

For instance, the data shows us that the average new home energy efficiency star rating is slowly increasing over time.

“The Portal allows us to generate insights back to the community and government to make better decisions. That’s unique worldwide. I’m not aware of any other jurisdiction with this kind of data or service,” Mr Wright said.

The team also provides industry-specific data to the private sector.

“We provide builders and manufacturers with information on where sustainable houses are cropping up, allowing them to gear-up their supply chains for more sustainable housing or products in certain areas,” Mr Wright said.

Australian households are responsible for 24 per cent of our overall electricity use and 12 per cent of total carbon emissions.

Social science for sustainability

The team’s social scientists undertake cutting-edge research to understand the decisions Australian households’ make about energy efficiency and sustainable housing. Australians love a good ‘home reno’ TV show.

So, they supported the producers and tested the impact of Renovate or Rebuild, a new series showing ways to live in more sustainable, energy efficient and comfortable homes. It aired on Channel 9Life in 2021, and proved highly popular, reaching an audience of around 3,240,000.

Why is CSIRO involved? TV can be a powerful tool to reach a wide audience and enact change. CSIRO’s behavioural scientists provided guidance to the show’s producer, The Blue Tribe Company and North Light Productions. CSIRO also works with Office of Energy and Climate Change (OECC) Low Carbon Living Collaborative Research Centre (LCLCRC), Reliable, Affordable, Clean Energy CRC (RACE CRC).

Together, they created a show that encourages Australians to build, buy and renovate more sustainable and energy-efficient homes.

Afterwards, CSIRO’s social scientists evaluated the impact of Renovate or Rebuild through targeted surveys. Dr Danie Nilsson, behavioural scientist and postdoctoral research fellow, leads this work.

“Our findings suggest that the show has the potential to positively impact some viewers, as intended. This approach is a promising step in helping Australians live more sustainably and comfortably,” Dr Nilsson said.

CSIRO also works to help consumers understand energy ratings, and on a project that analyses a decade of social media data, using natural language processing, to determine how people talk about residential sustainability. This will help researchers to understand the best language to use to encourage more sustainable housing choices.

A potpourri of projects on energy efficiency

Michael Ambrose, Senior Experimental Scientist and former architect, works with Mr Wright and the team on a veritable smorgasbord of research projects. “There’s an enormous amount happening. We’re tackling a whole range of problems we know are coming in the future,” Mr Ambrose said.

Over the next few years, the team will set up annual research programs:

  • Addressing issues of overheating that may occur in energy efficient homes during heat waves; creating new ‘comfort standards’ to apply to houses, to avoid overheating and heat-related health impacts
  • Establishing a database of zero emission homes from around Australia, to showcase the different design approaches
  • Tracking and evaluating the success of minimum energy efficiency standards on the design and construction of residential homes. New homes in Australia must meet a minimum NatHERS star rating and the team is asking how Australia’s housing stock is tracking
  • Continuing our world-class building physics research by reviewing and improving their AccuRate NatHERS tool. For example, by creating a module that estimates heat flow through concrete slabs. It’s incredibly complex and detailed, incorporating things like water table, depth, soil moisture content and more
  • Looking at the effects on the energy grid of a great stock of energy efficient homes and the role residential energy efficiency might play in the overall decarbonisation discussion
  • Investigating energy efficiency in apartments (which made up 58 per cent of all energy rating certificates in New South Wales in 2021). The team wants to know more about the real-world performance of Australia’s apartments
  • Testing the airtightness of newly built Australian houses and apartments and working with the NatHERS Administrator to ensure good building sealing is rewarded
  • Researching issues of condensation and moisture in residential building

Skilling up the next generation of scientists

“Over the last few years, the team’s grown from six to 19 people. And we’re training a whole range of PhD students,” Mr Wright said. “We try to graduate one building physics PhD a year to keep a pipeline of qualified people in the industry.” Mr Wright’s message is clear: come and work with us, partner with us, and ask us your curly questions!

“I’d love people to get in touch with us and ask us questions. Whether you’re a homeowner, a researcher, a builder, or a manufacturer with technical questions. We want to be really accessible.”

This sponsored editorial was brought to you by CSIRO. For more on CSIRO’s energy efficiency research, visit or contact Anthony Wright directly on

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