There are three components to an emissions projection, the land use, the consumption intensities and the emissions factors. Net-zero policies or intervention areas can then be encoded as a way of modifying one or many of these.

Land use is specifically excluded from modification — we want to understand the impact of a policy given that population and economic growth remain the same across each scenario.

This leaves a number of ways in which an intervention area may be encoded.

The first way of reducing emissions is to reduce the intensity at which consumption produces emissions by modifying an emissions factor.

For example, the roll-out of clean electricity generators across eastern Australia’s electricity grid will see the emissions intensity of electricity come down.

We use this method to model the grid decarbonisation, renewable hydrogen and syngas, improving vehicle fuel efficiency standards and the electrification of public transport.

The second way of reducing emissions is to reduce consumption or production of a resource, for example, through energy efficiency measures that reduce the amount of gas or electricity needed to power a building.

We use this method to model new building standards, some building retrofit strategies and per-person travel or waste reductions.

The final way of reducing emissions is to shift resource consumption or production to a less emissions intensive resource, for example, replacing internal combustion engine vehicles with electric vehicles, especially in the future when the emissions factor of electricity is much smaller.

We use this method to model some building retrofit strategies, electric vehicle uptake, transport mode shift and the waste diversion interventions.