Victoria’s policy to ban gas connections for new residences from next year would cut the state’s greenhouse gas emissions by almost a sixth compared with typical new dual electric and gas-run homes, analysis by the state government has found.
The government’s ban on new homes connecting to gas, announced in July, drew some criticism from those who argued emissions would actually rise in the short-term because the state’s electricity sector had a higher emissions intensity than gas.
However, analysis provided to Guardian Australia by the Department of Energy, Environment and Climate Action found a new, all-electric home would have 16% lower emissions than a new dual gas-electric home, saving 900kg of carbon-dioxide equivalent (CO2-e) a year.
Over a 10-year period, the emissions gap would widen further, assuming the electricity sector continued to decarbonise.
For the 2024-2034 period modelled, new all-electric homes would boast 29% lower emissions than equivalent dual-fuel ones, saving 13.5 tonnes of CO2-e.
The analysis is based on the new seven-star energy efficiency standards that start from next May. It also assumes the appliances used for space heating are high-efficiency, multi-split air conditioning systems.
Lily D’Ambrosio, Victoria’s energy minister, said all-electric homes required less energy to run than dual-fuel counterparts, saving owners money and cutting emissions.
“Modern electric appliances will reduce their emissions and save them $1,000 on their yearly energy bills, or up to $2,200 for households that also have solar installed,” D’Ambrosio said.
The new minimum requirements for home construction, including better insulation, would make them more sustainable. That was particularly so when combined with the more efficient heating and cooling and other electric appliances in the market.
Victoria is the largest jurisdiction in Australia to phase out gas in new homes, a path also being followed in the ACT and some councils, such as the City of Sydney.
Supporters of the Victorian decision include the Masters Builders Association Victoria and the Property Council of Australia, who say it gives certainty to the housing industry. Groups such as the Royal Australian College of General Practitioners said the move also reduced exposure to indoor air pollution while helping to tackle climate change.
The government assessment was based on a dual-fuel home requiring 4.3 megawatt-hours of electricity a year and burning 43.5 gigajoules of gas. An all-electric home would use 6.3MWh of power a year.
Alan Pears, an energy efficiency expert with RMIT University, said the analysis hinged on the quality of the appliances, particularly heat pumps.
Still, a house built to the current six-star standard of construction in Victoria required only a third as much heating as a typical two-star home, Pears said.
Switching to an all-electric residence even for existing homes could cut emissions relative to dual-fuel ones although “it’s a close-run thing in the short term”. Over time, though, the savings would widen as wind and solar energy knock coal and even gas out of the grid, reducing emissions-intensity, he said.
Alison Reeve, one of the authors of a recent Grattan Institute report about getting off gas, said the Victorian government was “not wrong” to use a new house as the basis for its calculations. That implied a home using about 55% less electricity for heating compared with the average one, but only 21% less gas.
It also assumed a highly efficient heat pump that put out four units of heat for every unit of electricity consumed, compared with a three-for-one assumption used in the Grattan paper. The emissions factor for gas was also slightly higher in the government’s assessment because it assumed some upstream emissions such as leaks from pipes.
“There are upstream emissions associated with electricity too, from the coalmining and gas extraction that still provide the majority of our electricity,” Reeve said. Including those would taper some of the electricity-over-gas advantage.
Still, the longer people take to build a new home, the more the emissions benefits of switching to electric only would likely increase.
“If a property developer gets a planning permit for a new development today, and takes three years to build those houses, by the time someone moves in and starts using the heater/stove, the Victorian grid is projected to be 15% greener,” Reeve said.
