But the widened program will likely be accompanied by bigger gas bills for ACT customers.

Climate Change Minister Shane Rattenbury said the scheme - which has been used by almost half Canberra's households to try and cut down on their power usage, but was due to expire next year - will be extended to 2030. It will commence on January 1, 2021.

The scheme has cost more than $60 million, paid for by electricity retailers who have in turn passed the cost onto customers. However $70 million has been saved through the scheme to date, and participants are expected to see a total lifetime energy bill saving of $240 million.

It includes initiatives like ActewAGL's fridge buyback scheme and lightbulb replacement program, as well as rebates from the retailer to trade in old gas heaters and hot water units for newer electric systems.

More than 70,000 (or 45 per cent) of Canberra households have taken part in the scheme, including 15,000 rental households and 17,900 low-income households.

Average weekly savings for participating households were $5.65 per week in 2017.

Mr Rattenbury said since the program was introduced in 2012, it had achieved a carbon dioxide reduction equivalent to removing 144,000 cars off Canberra roads for a year.

In 2017 alone, the scheme saved enough energy to power more than 21,000 households for one year, Mr Rattenbury said.

“The scheme is highly cost effective, delivering $2 in savings for every dollar spent. Preliminary modelling estimates that an [energy efficiency scheme] 10-year extension will cost up to a cumulative $209 million over 10 years while delivering lifetime energy bill savings of $444 million," Mr Rattenbury said.

But as the ACT transitions to 100 per cent renewable energy in 2020, Mr Rattenbury said the scheme would look to "optimise environmental and social outcomes", by focusing on cutting greenhouse gas emissions and reducing power bills for low-income households.

A 2018 review of the program found poorer households and renters faced higher electricity costs by contributing to the costs of the scheme without obtaining any direct benefits.

The expanded scheme would include more opportunities for low income households to participate, either by increasing the priority household target or expanding the types of households eligible for rebates.

It would incentivise Canberrans to switch from gas to efficient electric appliances and encourage homeowners to install insulation.

Heating and cooling makes up over 60 per of household energy usage in the ACT, which is much higher than most other Australian jurisdictions.

Mr Rattenbury said the ACT government would derive lessons from the pink batts affair and the ensuing royal commission to ensure the insulation was installed safely.

“Our team is in the process of consulting stakeholders such as Access Canberra, Worksafe ACT and industry experts in the development of a possible new insulation activity that would be delivered safely," Mr Rattenbury said.

The scheme may also stretch beyond the energy sector, to allow incentives for for zero emissions
vehicles.  Transport emissions have been identified as the next big hurdle as the ACT moves to zero net emissions by 2045, with more than 60 per cent of the territory's emissions predicted to come from the sector post-2020.

However the government is considering placing an obligation on gas retailers to meet energy saving targets, as they do with electricity providers.

Retailers face penalties if they do not meet a target equivalent to 8.6 per cent of their total electricity sales, but can meet their obligations by taking part in the energy efficiency scheme.

Like the electricity-side, it is presumed gas retailers will also pass the cost onto customers.

Mr Rattenbury said one third of the energy saving obligation could be placed on gas retailers - reflecting the ratio of electricity and gas savings modelled for the scheme extension - although gas retailers would be consulted first.

“Preliminary modelling estimates that a third of the energy saving obligation would reduce lifetime energy consumption by 3000 terajoules and contribute approximately 75,000 tonnes of carbon dioxide equivalent in lifetime emission savings,” he said.

While the ACT has historically benefited from low energy prices compared to the rest of Australia, both gas and electricity prices have more than doubled over the last decade.

The Australian Energy Regulator last month revealed ACT consumers paid the highest price for gas in the nation, at $1594 for middle-income households and $1292 for low-income households with a concession.

However this was offset by the price of electricity. Canberrans paid the second-lowest annual power bill in the country during 2017-18; an average of $1803 for middle income earners and $1502 for low-income earners with a concession.