The embodied energy associated with replacing gas heating with electric systems is significant and access to product origin information is crucial to help people make informed decisions, the study published in the Journal of Building Engineering found.

The research used ActewAGL data to compare energy output before and after upgrading from a gas to an electric heating and cooling system in 59 residential buildings. The results showed operational energy savings offset the embodied energy for short-term climate change, fossil and nuclear energy use, mineral resources use and ozone layer depletion.

However, long-term climate change, as well as a range of other impacts associated with materials used to manufacture heating and cooling systems, could only be offset through transitioning the grid away from its reliance on coal.

Kristy Bartlett looked for gas heating when purchasing a family home in Spence in 2012. She said a ducted-gas system was considered the best option at the time.

The household replaced the gas system with electric heating and cooling in August last year, driven by a desire to reduce emissions.

Having already purchased a portable induction stove top, the plan is to replace the gas cooker and hot-water system next.

Ms Bartlett said there had been some confliction over whether to replace things right away or wait until they were at the end of their life cycle.

"We are committed to changing everything we can for the environment, but taking it in steps," she said.

In Australia, depending on the climate, heating and cooling accounts for 20 to 50 per cent of the total energy use of residential buildings.

Renewables accounted for 23 per cent of Australian electricity generation in 2019-2020, which was data used for the study. There is no exact data on the energy mix of the ACT, as its reported under the NSW energy generation, where 19 per cent of electricity generation was from renewable energy. The ACT government reported its electricity-related emissions were zero in 2020-21 due to its renewable electricity supply.

Ina Eileen Peukes, a PhD student from Edinburgh Napier University who worked at ActewAGL at the time, undertook the research to help decision makers choose between the most environmentally friendly heating and cooling options, taking future grid developments into consideration.

The research included the extraction of the raw materials, transport, manufacturing of the new appliance, transport to the construction site, the operational energy output, as well as the transport and the disposal of the old appliance.

The study considered the installation company travels on average 53.61kms to the customer within the ACT. After the removal of the old appliance and the installation of the new appliance, it is assumed the same distance is driven to reach the recycling facility. The transportation from the recycling facility in Canberra to the recycling facility in Sydney is assumed to be 290km by truck.

The research also calculated the environmental impact of shipping components of the reverse-cycle air conditioner from South East Asia, as well as its transportation from the supplier in Sydney.

Ms Peukes said the results clearly illustrated that upgrading from gas to electric heating and cooling had environmental impacts which cannot be offset through the gas savings, despite most impacts being offset after decarbonising the electricity grid.

"If you make an environmentally conscious decision about what appliance to use, and what material is in that appliance, it would make sense to switch to electric heating and cooling instead," she said.

From a government and policy-maker point of view, there should be a stronger focus on the choice of materials. Also, the use of secondary materials could further decrease the environmental impacts of appliances, the research found.

With a further decarbonisation of the electricity grid, the impacts of gas to electric heating and cooling upgrades can be reduced.

"As there is a high likelihood that households will switch from heating only to heating and cooling systems, it is necessary to assess common energy efficiency upgrades to aid decision makers in choosing the most environmentally friendly solution on the market," the study found.

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Dan Cass, executive director of Rewiring Australia, said no nation harvests as much energy from the sun as Australia. He said to decarbonise the economy swiftly, Australia needed to make better use of that advantage.

Rewiring Australia are a non-for-profit which advocates for the electrification of businesses and homes. Saul Griffith, author of Electrify and The Big Switch, is its chief scientist.

Mr Cass said while Australians must absolutely replace gas heating and cooling with solar-backed electric systems, electrification must also include water heating with heat pumps, cooktops and vehicles.

"Our research shows that this shift becomes cost neutral from around 2025, but with investment from government now, we can accelerate the process, iron out any kinks and then sell our expertise and knowledge to the world," he said.

"Home owners should begin replacing their gas appliances as soon as they can and powering the new electric versions with rooftop solar. This will have both the biggest impact and the best savings for homes.

"Every home is different and we are all on a decarbonisation journey, but ultimately when a fossil fuel device ends its life cycle, the next version should be electric."

Mr Cass said the ACT had already made great progress and if its ambition kept growing, it could absolutely phase out all fossil fuel by 2045.

"They could do it 10 years faster than that and create millions in savings for ACT communities at the same time," he said.

"Australian rooftop solar is the cheapest source of energy in the world, its lifetime cost is about three cents per kWh, compared to a grid cost of near 30 cents.

"The electrified future will require less energy, because fossil fuel machines have a large amount of thermodynamic waste, but we will need more clean electricity.

"A big part of achieving this will be fully embracing grid neutrality, where it's as easy and attractive for households to sell excess energy into the grid at peak moments as it is for large power companies."

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