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Intervention areas
Written by Tom Watson
Updated over a week ago

This section will cover off the specific intensity and/or emissions factors modifications for each of the intervention areas with specific details included.


Residential and non-residential building standards

Specifically for the purpose of these intervention areas, the sectors are actually split into four “vintages” — categories that classify when the building was or will be built. This is to accommodate the fact that newer buildings are built to higher energy efficiency standards, and so their intensities for electricity and gas are expected to be lower.

The four vintages used are:

  • Existing

  • Built in the 2020s

  • Built in the 2030s, and

  • Built in the 2040s

Buildings in each vintage perform equally for all years into the future, which is why it is important to set high building standards earlier, as once a building is built its opportunity to decrease its emissions footprint is limited.

Additionally, new building standards cannot impact the existing building stock — only when it is demolished and replaced.

The applied intensities vary by location, as different areas tend to have different sized dwellings, but generally they represent buildings with the qualities:

  • Residential

    • No change: Dwellings built according to the building and BASIX requirements prior to 2023

    • BASIX +10/+20: Dwellings built according to a moderately higher standard of energy efficiency than required prior to 2023, and achieve an extra 10 BASIX points for apartments or an extra 20 BASIX points for houses. This became the new minimum standard in 2023

    • BASIX +20/+40: Dwellings built to a much higher standard of energy efficiency than is currently required, achieving an extra 20 BASIX points for apartments and an extra 40 for houses

    • Net-zero: Dwellings are built to a very high standard of energy efficiency as well as on-site energy generation such that their net energy use is zero.

  • Non residential

    • No change: Buildings are built according to the current building code

    • Standard: Commercial buildings are built to a NABERS 5.5 rating, while other non-residential buildings remain the same as the “No Change” selection.

    • High-efficiency: Commercial buildings are built to a NABERS 6.0 rating, retail, health and education buildings are 30% more efficient than existing buildings and industrial buildings are 20% more efficient.

    • Net-zero: Buildings are built to a very high standard of energy efficiency as well as with on-site energy generation such that their net energy demand is zero.

Residential and non-residential building retrofits

While the new building standards intervention areas above impact buildings that are built in the future, the retrofits intervention areas impact only the “existing” vintage of buildings. The execution of this intervention area is done by replacing electricity and gas intensities for the existing vintage.

  • Electricity efficiency: the electricity consumption intensity is replaced by another that is smaller by about 3%

  • Gas efficiency: the gas consumption intensity is replaced by another that is smaller by about 3%

  • Electricity and gas efficiency: the electricity and gas intensities are both replaced by intensities that are about 3% smaller

  • Electrification: the gas consumption intensity is set to zero while the electricity one is unchanged

  • High efficiency electrification: the gas consumption intensity is set to zero and the electricity intensity is replaced by one that is smaller by about 3%

The new intensity that is applied here is always a combination of the original, and one defined by the policy selection, where that combination is driven by the proportion of buildings targeted. For instance, if 0% of buildings are targeted the replaced intensity is identical to the original, but if 100% of buildings are targeted then the replaced intensity is just the one selected by the policy. For values in between, the intensity is a weighted average.

It is important to be aware of the emissions intensity of both electricity and gas when deciding upon the retrofits policies. The gas emissions factor will remain fairly constant into the future, only decreasing in those policy contexts that posit the use of renewable hydrogen. The electricity emissions factor on the other hand is expected to rapidly drop over the 2030s, so while domestic uses of gas, such as for heating and cooking, are currently less emissions intensive than the equivalent uses of electricity, that won’t always be the case. This does mean that going “too hard, too soon” on electrifying existing buildings may lead to a slight increase in emissions before dropping while waiting for the electricity grid to decarbonise may be more prudent.


Per person change in travel

This is the only intervention that posits a change in the demand for travel — the intervention areas below merely modify how that travel demand is met.

The demand for travel, on a per-person basis, may increase or decrease depending on the urban form of our city in the future. If suburban sprawl is allowed to increase and jobs continue to be focused in only a handful of centres, Sydneysiders may need to travel further on an average day to meet their needs. If, on the other hand, development and growth is able to be concentrated around walkable centres with high job containment and local amenity, Sydneysiders may find they’re able to meet a large proportion of their needs without travelling great distances.

This intervention area simply increases or decreases each of the transport consumption intensities by the percentage factor specified. In most modelling, TfNSW assume the daily travel needs of Sydneysiders to remain constant, which is equivalent to setting this value to 0 for all three decades.

Public transport electrification

While the last of Sydney’s suburban rail lines to be electrified was the Riverstone to Richmond segment of the T1/T5 in 1991, most buses and all ferries still consume fossil fuels.

TfNSW has a goal of transitioning all buses to electric by 2030, and have all operations net-zero by 2035 which corresponds to the “fast” selection. The slow and medium options model a 100% electrified public transport by 2050 and 2040 respectively.

This intervention area has effect of setting the public transport emissions factors to pre-defined values according to the slow/medium/fast roll-out scenarios. It posits no change to the use of public transport however.

Mode shift

This intervention area models only the replacement of car journeys to public and active transport journeys. A mode shift of 100% would see all journeys performed by a combination of public and active transport.

For each 1% of mode shift away from private cars, the consumption intensities (for all sectors) for petrol and electric cars are reduced by 1% and the public and active modes are increased using the following split







Active transport


EV take-up

The electric vehicle take-up intervention area models the service of private vehicle demand by electric vehicles in place of internal combustion engine vehicles. Each 1% of EV take-up yields a 1% decrease in the internal combustion engine car intensity and an equally sized increase in the electric vehicle intensity.

This implies that the percentage entered in the intervention area input is the total proportion of the private vehicle fleet, and not just the proportion of new sales.


Per person waste reduction

This intervention area includes strategies that seek to reduce the amount of landfill waste being generated on a per-person basis. For each 1% reduction the landfill intensity (across all sectors) is reduced by 1%.

Each of the following waste diversion intervention areas are modelled by estimating the materials present in landfill waste and diverting the appropriate streams to recycling or organics waste, which have a zero emissions factor.

Landfill waste is assumed to be made up of the following components, an assumption also used by the NGER determination

Waste mix type

Residential sectors (%)

Non residential sectors (%)




Paper and cardboard



Garden and park



Wood and wood waste












Rubber and leather



Inert waste



Recycling — packaging and source separation

Recycling is split into two intervention areas, one for producer level responsibility or packaging, the other for consumer level responsibility or separation into the yellow bin. Both intervention areas are assumed to have an equal impact.

Recycling shifts “inert” and “paper and cardboard” waste out of landfill in equal amounts and diverts them to “recycling”, however it is only the “paper and cardboard” that has an impact on emissions.


E-waste recycling is an environmental good due to the materials used in electronic products, however they form 0.5% of landfill waste and are inert from an emissions perspective. As such, the recyclable e-waste intervention area does model a shift of “inert” landfill waste to recycling, but the result doesn’t impact greenhouse gas emissions and is included for completeness.

Food and organics

For each 1% of food and organics diverted due to this intervention area, 1% of the “food” and “garden and park” sub-waste streams are removed from the landfill intensity and moved to the organics intensity. The result of this is a reduction in the landfill intensity, but also a modification of the landfill emissions factor to represent the new make-up of the landfill waste stream.

Waste to energy

After the total per-person waste has been reduced, and each of the above waste diversions have been factored in, the waste to energy intervention takes the specified proportion of the remaining landfill waste and removes it, and so also removing its emissions.

The impact of the waste to energy intervention then depends on the previous intervention areas — if less waste is diverted via other means, there’s more waste for “waste to energy” to remove and so its individual impact may be higher.

However, this is slightly optimistic as waste to energy is not exactly zero emissions, so other waste interventions should be used in preference.

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