Ever known exactly where you’re going, but not quite how to get there?

That’s the situation for Australia right now when it comes to cutting carbon emissions. We know we’re headed to net zero emissions – we made that commitment at the recent COP26 climate conference in Glasgow. We know when we’re going to get there: by 2050. But there are more ways than one to make the journey.

Cutting emissions requires action across all sectors of the economy – from energy to agriculture to transport. But as the Australian Sustainable Built Environment Council (ASBEC) has found, being smarter about how we use energy in the buildings where we live, work and are educated provide some of the cheapest and quickest ways to achieve the deep cuts we need. That’s partly because we’re already started. ASBEC’s 2018 report Built to Perform, about changes to the National Construction Code which governs minimum standards for all new Australian buildings, showed how mandating increases in energy efficiency performance over time will get us ready for net zero, and it’s already happening. It’s also because we’re going to build new buildings anyway; what we build now will still be standing in 2050 and beyond.

ASBEC is now looking ahead beyond efficiency, to the role that fuel choice can play. Our Rapid and Least Cost Decarbonisation of Buildings Discussion Paper, open for consultation until April 1, outlines three possible pathways to decarbonise our buildings and get to net zero emissions by 2050. Each of them has implications for cost, health and wellbeing for decades to come.

Renewable electricity is already part of our energy mix, with everything from large scale wind and solar farms to those PV panels springing up in their thousands on the rooftops of our homes. But while continuing to grow strongly, renewables still only represent around 35% of our energy use, with the rest involving various fossil fuels.

Many of our cities and towns have gas infrastructure, with huge networks of pipes bringing gas to homes and industry. This natural gas is a fossil fuel and still contributes to Australia’s emissions. Could other gases, generating fewer emissions, run through these pipes instead?

Biogas produced as a waste product from other processes could be captured and circulated via the gas pipes, recycling it and getting more “bang for buck” for the emissions created.

Another option is adding green hydrogen, which burns clean, producing only water as a by-product. This mixed gas would be different to the natural gas we use currently, so it might require some upgrades to infrastructure or end users’ appliances to work. Initially, it could be mixed in with existing gas supplies at a low rate like 10% to study the effect and determine the costs.

Scenario 1: Electrification with renewable electricity

Changing existing use of gas or other fossil fuels to electricity would allow renewables to be used for all our energy needs, from cooking dinner at home to powering a factory floor.

We’re used to electricity and we know the technology works. Generating renewable energy, from wind farms to rooftop solar, is getting more efficient, while economies of scale are making it cheaper to install.

But there could be costs involved. We’ll need to ensure our ageing energy grid can handle the increased demand, especially as more Australians make the move to electric vehicles. This applies within buildings too; those with older wiring might need upgrades. At the same time, we’ll need to fit new technology like heat pumps into existing building footprints.

If we take this path, we’ll need to decommission our gas infrastructure, causing an impact on gas businesses and the workers they employ. We’ll also need to act fast, adapting building regulations to ensure that all new buildings are built with renewable electricity, not gas, in mind.

Scenario 2: Renewable electricity + renewable gas

In this scenario, we could use the renewable electricity described above but continue to use the gas infrastructure, mixing in low or no emission gas to reduce overall emissions.

While this would provide a future for the gas industry, it could cost more. Our gas infrastructure is ageing, with much of it more than 40 years old. If we’re going to keep using gas, we will likely need a large spend to ensure the network is fit for purpose into the future. Similarly, new appliances and machinery that can handle the new mixes of gas might be expensive for both domestic and industrial building owners to purchase.

Scenario 3: Renewable energy + gas blend + offsets

This would cause minimal disruption, as we wouldn’t need new appliances or infrastructure.

But offsets, particularly land-based vegetation offsets offer only short-lived carbon removal and can be lost through bushfire or deforestation. Good quality vegetation offsets and options delivering more permanent storage are expensive, and likely to become more so if the demand rises sharply. Equally, many consumers might choose to move to fully electric solutions, leaving those on gas to pay higher prices as economies of scale are lost.

There’s also an investment risk for Australia on this path. With fossil fuels on the nose in many countries, international investment might head elsewhere, to countries with fully renewable electric solutions.

There’s still work to be done to determine the best way to achieve net zero by 2050, but Australia is headed in the right direction. ASBEC will be working hard to bring the combined knowledge and experience of the built environment sector to the table, so we can get where we’re going on the best path possible.