7. Travel emission factors

This travel emissions section provides detail on how to calculate emissions associated with both business travel and staff commuting.

Business travel emissions result from travel associated with (and generally paid for by) the entity. We provide factors for private and rental vehicles, taxis, public transport, air travel, helicopters and accommodation. Business travel emissions are indirect (Scope 3/Category 6: Business travel) if the entity does not directly own or control the vehicles used for travel.

If the entity owns or has an operating lease for the vehicle(s) these emissions are direct (Scope 1/Category 1: Purchased goods and services GHG Protocol) and should be accounted for in transport fuels(see section 3.3).

Staff commuting emissions result from employees travelling between their homes and their worksites. Emissions from staff commuting may arise from the use of private and rental vehicles, taxis, public transport, and air travel. Other emissions associated with working from home can be accounted for in section 6, ‘indirect business-related emission factors’.

Staff commuting emissions are indirect (Scope 3/Category 7: Employee commuting).

7.1 Overview of changes since previous update

A new age category has been added for Post-2020 passenger vehicles, with the Post-2015 category being renamed to 2015−2020 passenger vehicles. Because newer vehicles tend to be more fuel efficient, the emission factors within this new category are between 3.5 per cent and 5.5 per cent lower than the 2015−2020 age category. In this edition of the guide, the weighting methodology used to create the domestic average, large and medium sized aircraft is modified.

These emission factors are now calculated using the annual flight domestic distance travelled and the total number of domestic flights, for each aircraft type. Previously, the weighting applied was based on the share of total domestic traffic.The multiplier that is applied to account for the non-CO2 climate change effects of aviation has been revised downwards from 1.9 to 1.7, to be in line with the latest scientific evidence.1

A new factor for a passenger ferry was added this year, using data from Auckland Transport.

The three taxi spend-based emission factors reduced by between 11 per cent and 14 per cent, as a result of reductions in the applied fuel factor values, and the increased applied tariff rate from $3.20 to $3.52 per km.

The emission factors for hotel stays have been updated using factors from the 2023 edition of the Cornell Hotel Sustainability Benchmarking Index (CHSB) Index.

7.2 Passenger vehicles

This section covers emissions from private vehicles for which mileage is claimed, rental vehicles and taxi travel.

Travel, including rental vehicles, staff mileage and taxi travel are indirect (Scope 3) emissions. This is a change in guidance, to align better with leading practice. As with direct (Scope 1) emissions from transport fuels, the most accurate way to calculate emissions is based on fuel consumption data. Fuel-use data are preferable because factors such as individual vehicle fuel efficiency and driving efficiency mean that kilometre-based estimates of emissions are less accurate. However, this information may not be easily available.

The 2022 fleet statistics (table 16, table 17, table 18 and table 19) were taken from the Te Manatū Waka Ministry of Transport Vehicle Fleet Emissions Model. This provides energy (fuel and electricity) use per km travelled by vehicle.

Fuel-use based emission factors are above in section 3.

If the only information known is kilometres travelled, use the emission factors in this section. Factors such as individual vehicle fuel efficiency and driving efficiency mean that kilometre based estimates of carbon dioxide equivalent emissions are less accurate than calculating emissions based on fuel-use data.

If the vehicle size and engine type are known, use the factors in table 16, table 17, table 18 and table 19. Table 20 lists default private car emission factors and table 21 lists the rental car emission factors based on distance travelled. Table 22 lists emission factors for taxi travel based on dollars spent and kilometres travelled.

Table 15 details engine sizes and typical corresponding vehicles.

Table 15: Vehicle engine sizes and common car types

Table 16: Pre-2010 vehicle fleet emission factors per km travelled

Table 17: Vehicle fleet emission factors per km travelled, 2010–2015

Table 18: Vehicle fleet emissions per km travelled, 2015−2020

Table 19: Post-2020 vehicle fleet emissions per km travelled

Table 20: Default private car emission factors per km travelled for default age of vehicle and <3000 cc engine size

Note:Defaults are based on the average age of the vehicle fleet (pre-2010 for petrol and diesel including hybrids, and 2010–2015 for all plug-in cars) and most common engine size (2000–3000 cc). Source: Te Manatū Waka Ministry of Transport

Table 21: Default rental car emission factors per km travelled

Note: Defaults assume a 2015−2020 fleet for rental cars and engine size of 1600–<2000 cc.

We were unable to source more up-to-date data on the New Zealand taxi fleet to produce a representative vehicle type for the taxi (regular) factor. Therefore, this factor is derived from an average of the factors for a petrol, diesel, petrol plug-in hybrid and electric vehicle, for a 2010−2015 fleet and 2000–3000 cc vehicle class.

Table 22: Emission factors for taxi travel

7.2.1 GHG inventory development

Entities should gather the activity data on passenger vehicle use with as much detail as possible, including age of the vehicle, engine size, fuel type and kilometres travelled. If information is not available, we provide conservative defaults to allow for overestimation rather than underestimation.

If fuel-use data are available, see section 3.3.

If fuel-use data are not available, collect data on kilometres travelled by vehicle type and multiply this by the emission factor based on distance travelled for each GHG. If the vehicle is electric and the charging point is within the entity’s boundaries, this is a direct (Scope 1) emission source and emissions are zero. If travel is by rideshare apps (ie, Uber, YourRide, Waka Rider, Ola or Share Your Ride) we recommend using the taxi travel emission factors by distance travelled (table 22). If this information is not available, use the taxi emission factors per dollars spent.

Because plug-in hybrids operate on both a fossil fuel and electricity, two separate emission factors should be applied, that for the fossil fuel (petrol or diesel) and that for electricity. The plug-in hybrid electric vehicle electricity factor includes both the electricity and the electricity transmission and distribution loss factor.

Applying the equation E = Q x F (section 2), this means:

E = emissions from the emissions source in kg CO2-e per year

Q = distance travelled by vehicle type (km)

F = emission factors for correlating vehicle type from table 16 to table 22

PASSENGER VEHICLES: EXAMPLE CALCULATION

7.2.2 Emission factor derivation methodology

The 2022 fleet statistics were taken from the Te Manatū Waka Ministry of Transport Vehicle Fleet Emissions Model. This provides energy (fuel and electricity) use per 100 km travelled by vehicle.

We split the fleet into four categories and develop average emission factors for these.

• The pre-2010 fleet is based on the average fuel consumption data from 1970 to 2010.

We assume there are no electric vehicles or plug-in hybrid vehicles.

• The 2010–2015 fleet is based on the average fuel consumption data from vehicles

produced between 2010 and 2015.

• The 2015−2020 fleet is based on the average fuel consumption data from vehicles

produced between 2015 and 2020.

• The post-2020 fleet is based on the average fuel consumption data from vehicles

produced from 2021 onwards.

Note that some guidance documents, such as those published by the UK Department for Energy Security and Net Zero (formerly published by the Department of Business, Energy and Industrial Strategy), apply an uplift factor to passenger vehicles.

This accounts for the real-world effects on fuel consumption, such as the use of air conditioning, vehicle payload, gradient and weather. We do not apply an uplift factor here, because the Vehicle Fleet Emissions Model is based on real-world driving and fuel use.

For each category, default vehicles are based on the 2000–3000 cc engine size, as it is the most common size for light passenger vehicles in New Zealand based on Motor Vehicle Register open data.2

Table 23: Fuel consumption in litres per 100 km

3Motor Vehicle Register: www.nzta.govt.nz/vehicles/how-the-motor-vehicle-register-affects-you/motorvehicle-registrations-dashboard-and-open-data/.

Source: Te Manatū Waka Ministry of Transport Vehicle Fleet Emissions Model

The equation used to calculate the emission factor for each GHG is:

r𝑒𝑎𝑙 𝑤𝑜𝑟𝑙𝑑 𝑓𝑢𝑒𝑙 𝑐𝑜𝑛𝑠𝑢𝑚𝑝𝑡𝑖𝑜𝑛 (𝑙𝑖𝑡𝑟𝑒𝑠) × 𝑒𝑚𝑖𝑠𝑠𝑖𝑜𝑛 𝑐𝑜𝑛𝑣𝑒𝑟𝑠𝑖𝑜𝑛 𝑓𝑎𝑐𝑡𝑜𝑟

100 (𝑘𝑚)

Dividing by 100 gives a factor for litres (or kWh) per fuel per km. Use this with the fuel emission factors to calculate emissions per km.

Multiply the values for fuel consumption by the emission conversion factors in table 4.

New Zealand Transport Agency vehicle registration data is unchanged from the 2022 guidance, where the average year of manufacture for the taxi fleet was 2012, and 2015 for the rental fleet4 We assumed a 2010–2015 fleet for taxis and post-2015 fleet for rental cars.

The taxi (regular) factor is derived from an average of the factors for a petrol, diesel, petrol plug-in hybrid and electric vehicle, for a 2000–3000 cc vehicle class. These workings are in table 24.

Table 24: Data used for calculating the taxi (regular) emission factor

TaxiCharge NZ Ltd advised that the current average price per kilometre in a taxi is $3.52. North Island’s average rate = $3.35, while South Island’s average = $3.81.

The calculation to develop the emission factors for taxi based by $ spend is:

𝑒𝑚𝑖𝑠𝑠𝑖𝑜𝑛𝑠 𝑝𝑒𝑟 $ 𝑠𝑝𝑒𝑛𝑑 = 𝑒𝑚𝑖𝑠𝑠𝑖𝑜𝑛𝑠 𝑝𝑒𝑟 𝑘𝑚

                       $3.20 𝑝𝑒𝑟 𝑘𝑚

Table 25 shows the fuel economy and emissions per kilometre figures used to derive the taxi regular factor.

Table 25: Figures used to derive the taxi regular factor

The private car default is based on the average age of light passenger vehicles in the New Zealand fleet, back-calculated to the year of manufacture, with the fuel consumption factors in table 26 applied.

According to Te Manatū Waka Ministry of Transport’s The New Zealand 2022 Vehicle Fleet:

Data Spreadsheet,5the average age of light passenger vehicles in 2021 was 14.87 years. This corresponds to a 2007 year of manufacture.

Furthermore, according to the above source, the most common size of light passenger vehicles is between 1600 cc and 2000 cc, which puts it in the 2000–3000 cc category. For hybrid and

electric vehicles, we assumed a 2015−2020 fleet consumption for a 2000–3000 cc equivalent engine size.

Table 26: Energy consumption per 100 km for average light passenger vehicles

The default emission factor for rental cars is the same as for vehicles in the post-2015

1600–2000 cc category.

7.2.3 Assumptions, limitations and uncertainties

Emission factors from fuel are multiplied by real-world consumption rates for vehicles with different engine sizes. The uncertainties embodied in these figures carry through to the emission factors. For petrol vehicles, we multiplied the real-world consumption by ‘regular petrol’ emission factors from the fuel emission source category. This may overestimate emissions for some and underestimate emissions for others.

According to Te Manatū Waka Ministry of Transport’s The New Zealand 2022 Vehicle Fleet: Data Spreadsheet, the most common size of light passenger vehicle is between 1600 cc and 2000 cc, which puts it in the 2000–3000 cc category. Therefore, the default emission factors (for vehicles of unknown engine size) are the same as for a <3000 cc vehicle.

The Vehicle Fleet Emissions Model contains uncertainties about the fuel consumption figures provided. Emission factors represent the average fuel consumption of vehicles operating in the real world under different driving conditions, across all vehicle types in that classification.

We assume there are no electric cars or hybrids in the pre-2010 fleet.

7.3 Public transport passenger travel

The emission factors for public transport for passenger travel on buses, trains and a ferry were provided by Auckland Transport. The unit used for these emission sources are passenger kilometres (pkm).

The national average for the bus factor is unchanged from the previous edition.

Table 27: Emission factors for public transport

7.3.1 GHG inventory development

To calculate public transport passenger emissions, collect data on the type of transport and distance travelled, and multiply this by the emission factors for each gas. Entities could conduct a staff travel survey to quantify these emissions.6

Applying the equation E = Q x F [section 2] (2_how-to.qmd#Calculating_an_emissions_factor), this means:

E = emissions from the emissions source in kg CO2-e per year

Q = distance travelled, by vehicle type (km)

F = emission factors for correlating vehicle type, from table 27.

PASSENGER BUS: EXAMPLE CALCULATION

7.3.2 Emission factor derivation methodology

7.3.2.1 National average bus

To calculate the emission factor for national average bus travel we used the New Zealand Transport Agency passenger travel data28 (table 28) to estimate the national average loading capacity of seven people per bus.

Table 28: National bus passenger kilometres in 2020/21

7GHG Protocol Technical Guidance for Calculating Scope 3 Emissions:

https://ghgprotocol.org/sites/default/files/standards_supporting/Chapter6.pdf.

8New Zealand Transport Agency, Passenger data, accessed September 2020:

www.nzta.govt.nz/assets/userfiles/transport-data/PTPerformance.xlsx

The passenger loading per bus for the different regions for 2020/21 is shown in table 29.

Table 29: National bus passenger loading by region

We then divided the per kilometre emission factor for diesel buses in table 28 by the national passenger/bus loading rate to give the emissions per gas, see table 35

Table 30: Emission factor for national average bus

7.3.2.2 Auckland buses

To calculate the emissions from Auckland buses we used the most recent data available, which were from the year 2023. This information was from Auckland Transport.

Data for the electric and hydrogen buses are in table 31. The distance travelled by electric and hydrogen buses for each 2023 quarter was multiplied by an estimated average bus power rating of 1.075 kWh and 7.05 kWh per kilometre respectively.29 The resultant energy consumption was multiplied by its respective quarterly electricity emission factor (including the transmission and distribution loss factor of electricity) to produce quarterly emissions totals. These totals were then divided by the quarterly totals for passenger kilometres travelled. The final emission factor is weighted based on the quarterly emissions totals and quarterly passenger kilometres travelled.

Table 31: Auckland Transport 2023 data for electric and hydrogen buses

Data for the diesel buses are in Table 32. The annual distance travelled was multiplied by an estimated fuel efficiency of 0.433 litres per kilometre travelled.9The resultant energy consumption was multiplied by the diesel emission factor, to produce an annual emissions total. This total was then divided by the annual passenger kilometres travelled, to produce the final emission factor.

Table 32: Auckland Transport 2023 data for diesel buses

7.3.2.3 Auckland trains

To calculate the emissions from Auckland trains we used the most recent data available, which were from the year 2023 and 2021/22 for electric and diesel trains respectively. Diesel trains stopped operating in the region in August 2022. This information was from Auckland Transport.

Data for the electric and diesel trains are in table 33. The diesel fuel used by diesel trains was multiplied by the diesel emission factor (in table 4) to produce an annual emissions total. This total was then divided by the annual passenger kilometres travelled, to produce the final emission factor.

The electricity used by electric trains for each year 2023 quarter, was multiplied by the respective quarterly electricity emission factors (including the transmission and distribution loss factor of electricity) to produce quarterly emissions totals. These totals were then divided by the quarterly totals for passenger kilometres travelled. The final emission factor is weighted based on the quarterly emissions totals and quarterly passenger kilometres travelled.

The diesel fuel used by diesel trains was multiplied by the diesel emission factor (in table 4) to produce an annual emissions total. This total was then divided by the annual passenger kilometres travelled, to produce the final emission factor.

Table 33: Auckland train data

The train average factor is weighted based on the emission factors for electric and diesel trains and the respective passenger kilometres travelled.

7.3.3 Auckland ferry

To calculate the emissions from ferry travel we used the most recent data available, which were from the year 2023. This information was from Auckland Transport and covers the 30 ferries operating in the Auckland region.

The annual distance travelled by diesel ferries in the year 2023 was multiplied by an estimated average fuel consumption rate of 4.84 l/km to estimate the diesel used by public transport ferries in Auckland region.10 The diesel used was then multiplied by the diesel emission factor (in table 4) to produce an annual emissions total. This total was then divided by the annual passenger kilometres travelled, to produce the final emission factor.

Table 34: Ferry data

7.3.4 Assumptions, limitations and uncertainties

Limited data are available for areas outside the Auckland region.

These metro commuter rail emission factors are assumed to be appropriate for use on any commuter rail line in New Zealand.

7.4 Public transport vehicles

Public transport vehicle emissions include those from buses. Emissions are calculated for the whole vehicle. This approach is appropriate for transport operators or if a bus is chartered. Table 35 details these emission factors.

Buses: We calculated the emissions of different buses using Te Manatū Waka Ministry of Transport Vehicle Fleet Emissions Model data for fuel consumption in litres per 100 kilometres. The guide presents the data in emissions per kilometre.

There are no changes to the data from the previous edition of this guide. The data used are from 2019.

Table 35 details the data provided to calculate the emission conversion factors.

Table 35: Bus emission factors per km travelled

7.4.1 GHG inventory development

To calculate public transport emissions, collect data on the type of transport and distance travelled, and multiply this by the emission factors for each gas. Applying the equation

E = Q x F section 2, this means:

E = emissions from the emissions source in kg CO2-e per year

Q = distance travelled, by vehicle type (km)

F = emission factors for correlating vehicle type, from table 35.

DIESEL BUS: EXAMPLE CALCULATION

7.4.2 Emission factor derivation methodology

The average age of the bus fleet is 16.4 years (according to Te Manatū Waka Ministry of Transport fleet statistics). Therefore, we applied an average fuel consumption factor for a pre-2010 fleet to the bus fleet from the 2019 Vehicle Fleet Emissions Model.

Table 36: Fuel/energy consumption per 100 km for pre-2010 fleet buses

Using the information in table 36 and appropriate emission factor, the equation is:

𝑒𝑛𝑒𝑟𝑔𝑦 𝑐𝑜𝑛𝑠𝑢𝑚𝑝𝑡𝑖𝑜𝑛 × 𝑒𝑚𝑖𝑠𝑠𝑖𝑜𝑛 𝑓𝑎𝑐𝑡𝑜𝑟 = 𝑔𝑟𝑒𝑒𝑛ℎ𝑜𝑢𝑠𝑒 𝑔𝑎𝑠 𝑒𝑚𝑖𝑠𝑠𝑖𝑜𝑛𝑠 𝑝𝑒𝑟 𝑘𝑚

100 (𝑘𝑚)

Where:

• fuel/energy consumption = units of energy per 100 km travelled

• emission factor = the emission factor from table 4 or table 9.

This allows you to use distance travelled as a unit for calculating emissions. If there are data on the quantity of fuel used, refer to transport fuel emission factors.

7.4.3 Assumptions, limitations and uncertainties

The Vehicle Fleet Emissions Model historical year results have been carefully calibrated to give a total road fuel use that matches MBIE’s road fuel sales figures. The sources used to develop these emission factors will have inbuilt assumptions, limitations and uncertainties. To investigate these, see the documents referenced.

7.5 Air travel

This section covers emission factors for domestic and international air travel for entities seeking to determine the emissions from business travel.

7.5.1 Domestic air travel

This section provides emission factors based on data from 2023. Domestic air travel is a common source of indirect (Scope 3) emissions for many New Zealand entities.

For air travel emission factors, multipliers or other corrections may be applied to account for the radiative forcing of emissions arising from aircraft transport at high altitude (jet aircraft). Radiative forcing helps entities account for the wider climate effects of aviation, including water vapour and indirect GHGs. This is an area of active research and uncertainty, aiming to express the relationship between emissions and the climate warming effects of aviation, but there is yet to be consensus on this aspect.

In this guidance, emission factors with a radiative forcing multiplier refers to the indirect climate change effects (non-CO2 emissions eg, water vapour, contrails, NOx). Emission factors without a radiative forcing multiplier refers to the direct climate change effects (CO2, CH4 and N2O). If multipliers are applied, entities should disclose the specific factor used including its source and produce comparable reporting. Therefore, avoid reporting with air travel conversion factors in one year and without in another year, as this may skew the interpretation of your reporting.

The decision to apply the Radiative Forcing Index, and to what type of air travel (flight altitude) should be guided by the requirements of your intended use and users.

In terms of the small and medium aircraft, a radiative forcing multiplier may not be required given the lower altitude at which these aircrafts typically fly. However, these emission factors are provided in the tables below for completeness, and for users wanting to take a conservative approach to their reporting.

Table 37 provides the emission factors without the radiative forcing multiplier applied. Table 38 provides emission factors with a radiative forcing multiplier of 1.7 applied.

Table 37: Domestic air travel emission factors without a radiative forcing multiplier

Table 38: Domestic aviation emission factors with a radiative forcing multiplier

We have provided a national average emission factor, and three factors based on the aircraft size: large, medium or small aircraft. A large aircraft in New Zealand would be an Airbus A320neo, A320ceo and A321neo. A medium aircraft has between 50 and 70 seats (ie, regional services on an ATR 72 or de Havilland Q300) and a small aircraft has fewer than 50 seats. If the aircraft type is unknown, we recommend using the national average.

7.5.1.1 GHG inventory development

To calculate emissions for domestic air travel, collect information on passengers flying, their departure and destination airports, flight length, travel class and, if practical, the type of aircraft. Your travel provider may be able to provide this information.

If the type of aircraft is unknown, use the national average emission factors. Calculate distances using online calculators such as www.airmilescalculator.com. Multiply the number of passengers by the distance travelled to obtain the pkm.

Applying the equation E = Q x F (section 2), this means:

E = emissions from the emissions source in kg CO2-e per year

Q = passengers multiplied by distance flown (pkm)

F = emission factors from Table 37 to table 38

DOMESTIC AIR TRAVEL: EXAMPLE CALCULATION

7.5.1.2 Emission factor derivation methodology

We developed emission factors for aircraft type with data supplied by Air New Zealand and Te Manatū Waka Ministry of Transport. We calculated an average emission factor for domestic air travel using data from the 2016, 2020 and 2023 calendar years. Table 39 details the types of aircraft running domestic flights, using Air New Zealand data and 2016 Te Manatū Waka Ministry of Transport data to calculate the emission factors.

An average emission factor has also been provided where the aircraft type is unknown (see Table 37 and table 38). Entities that own aircraft could calculate emissions based on the fuel consumption data.

Table 39: Domestic aviation data (2016, 2020 and 2023)

Note: * Average calculated using data from 2016, 2020 and 2023.

To calculate the emission factor, first calculate average fuel (kg) per flight for each aircraft:

𝑎𝑣𝑒𝑟𝑎𝑔𝑒 𝑡𝑜𝑡𝑎𝑙 𝑓𝑢𝑒𝑙 𝑢𝑠𝑒𝑑 (𝑘𝑔)

𝑎𝑣𝑒𝑟𝑎𝑔𝑒 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑓𝑙𝑖𝑔ℎ𝑡

Then calculate average fuel (kg) per passenger:

𝑎𝑣𝑒𝑟𝑎𝑔𝑒 𝑓𝑢𝑒𝑙 (𝑘𝑔) 𝑝𝑒𝑟 𝑓𝑙𝑖𝑔ℎ𝑡

𝑎𝑣𝑒𝑟𝑎𝑔𝑒 𝑠𝑒𝑎𝑡𝑠 × 0.8

Using this, next calculate fuel per passenger per km:

[𝑎𝑣𝑒𝑟𝑎𝑔𝑒 𝑓𝑢𝑒𝑙 (𝑘𝑔) 𝑝𝑒𝑟 𝑝𝑎𝑠𝑠𝑒𝑛𝑔𝑒] {.underline}

𝑎𝑣𝑒𝑟𝑎𝑔𝑒 𝑓𝑙𝑖𝑔ℎ𝑡 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒

The density of kerosene (the assumed aviation fuel) is 0.79 kg/l.11

Emission factors for each aircraft were determined by multiplying the fuel (litres) per passenger per kilometre by the kerosene (aviation fuel) emission factor in table 4

Table 40: Calculated emissions, without the radiative forcing multiplier, per aircraft type

Note: 2016 or 2020 data unless denoted otherwise. * Updated using 2023 data.

Table 41: Calculated emissions, with the radiative forcing multiplier, per aircraft type

Note: 2016 or 2020 data unless denoted otherwise. * Updated using 2023 data. For situations where the aircraft type is unknown, average emission factors are also provided for a domestic average, and for large, medium and small aircraft( see table 37 and table 38).

We then calculated a weighted average emission factor for each size category, using the aircraft types within that size range. The weighted averages are calculated using the annual flight domestic distance travelled and the total number of domestic flights for each aircraft type. This method applies an equal weighting of 50 per cent to both distance travelled and number of flights.

• large aircraft: A320neo, A320ceo and A321neo

• medium aircraft: ATR 72 and Q300

• small aircraft: British Aerospace Jetstream 32, Cessna Light Aircraft.

A national average emission factor was calculated using the same weighted average approach described above, this time considering the contribution each of the five large and medium aircraft types make to the overall distance travelled and number of flights.

7.5.1.3 Assumptions, limitations and uncertainties

We assume the fuel for domestic flights is kerosene (aviation fuel) and all the kerosene is combusted. The domestic emission factors are based on fuel delivery data. Therefore, it is not necessary to apply a distance uplift factor to account for delays/circling and non-direct routes (ie, not along the straight-line/great-circle between destinations). However, this should be considered for international air travel.

7.5.2 International air travel

International air travel emission factors are sourced directly from the UK Greenhouse gas reporting: conversion factors 2022, published by the UK Department for Energy Security and Net Zero (DESNZ) and have not been updated to the DESNZ 2023 factors. This is because the 2022 factors (unchanged from 2021) are calculated from 2018 and 2019 flight passenger data. The DESNZ 2023 update uses data from 2021, a period of significant impact because of the COVID-19 pandemic, specifically load factors. The implication of this update is significant because the 2023 updated factors are not at all reflective of reporting periods after the COVID-19 pandemic.

Because the DESNZ 2022 emission factors were developed using the GWP values from the AR4, the factors presented here have been converted to AR5 GWP values.

Entities wishing to report their international air travel emissions based on distance travelled per passenger could use the International Civil Aviation Organisation (ICAO) calculator12.This calculator considers aircraft types and load factors for specific airline routes but does not apply the radiative forcing multiplier (accounting for the wider climate effect of emissions arising from aircraft transport at altitude) or distance uplift factor to account for delays/circling and non-direct routes (ie, not along the straight-line/great-circle between destinations). If using the ICAO calculator to calculate emissions for international air travel, multiply the output by 1.08 to account for the 8 per cent distance uplift factor (see [section 7.5.3.3])(7_travel.qmd##Assumptions,_limitations_and_uncertainties) and then by 1.7 to apply a radiative forcing multiplier.

If you prefer not to use the ICAO calculator, we recommend the emission factors in table 42 and table 43. These emission factors follow those published online by the UK Department of Business, Energy and Industrial Strategy conversion factors (Conversion factors 2022: condensed set (for most users)) and include a distance uplift of 8 per cent and a radiative forcing multiplier of 1.7.

Table 42: Emission factors for international air travel without radiative forcing multiplier

Table 43: Emission factors for international air travel with radiative forcing multiplier

The emission factors from the UK DESNZ are calculated regarding the indirect and direct climate change effects. For continuity in this guidance, we have categorised the international air travel emission factors by whether a radiative forcing multiplier was applied, as outlined in this section. Further information can be found in paragraphs 8.37 to 8.41 in the 2023 UK DESNZ Methodology Paper for Conversion Factors.

7.5.2.1 GHG inventory development

To calculate emissions for international air travel, collect information on passengers flying, their departure and destination airports, flight length, travel class and, if practical, the type of aircraft. Your travel provider may be able to provide this information. Information on flight distance will be required to determine whether the short- or long-haul factors should be used.

To calculate emissions for international air travel, gather the information on how far each passenger flew for each flight. Multiply this by the factors in Table 42 or table 43. Use the specified emission factors for different cabin classes if information is available. If unknown, use the average emission factors. Applying the equation E = Q x F section 2, this means:

E = emissions from the emissions source in kg CO2-e per year

Q = passengers multiplied by distance flown (pkm)

F = appropriate emission factors from table 42 or table 43.

INTERNATIONAL AIR TRAVEL: EXAMPLE CALCULATION

7.5.1.3 Emission factor derivation methodology

The 2023 UK DESNZ Methodology Paper for Conversion Factors publication discusses the methodology in more detail, including changes over time.

7.5.1.4 Assumptions, limitations and uncertainties

The emission factors in table 42 and table 43 are based on UK and European data. The short-haul emission factor applies to international flights of less than 3,700 km. The long-haul factor applies to flights of more than 3,700 km.

The UK DESNZ endorses a great circle distance uplift factor to account for non-direct (ie, not along the straight-line/great-circle between destinations) routes and delays/circling. The 8 percent uplift factor applied by UK DESNZ is based on the analysis of flights arriving and departing from the United Kingdom. This figure is likely to be overstated for international flights to/from New Zealand (initial estimates from Airways New Zealand suggest it is likely to be less than 5 per cent). In the absence of a New Zealand-specific figure for international flights, we recommend an 8 per cent uplift factor. This figure is comparable to an IPCC publication, Aviation and the Global Atmosphere (refer to section 8.2.2.3)13, which suggests for European flights the average flight distance is about 9 per cent to 10 per cent greater than the actual flight track distance.

The emission factors refer to aviation’s direct GHG emissions including carbon dioxide, methane and nitrous oxide. There is currently uncertainty over the other climate change impacts of aviation (including water vapour and indirect GHGs, among other factors), which the IPCC estimated to be up to two to four times those of carbon dioxide alone. However, the science is currently uncertain and New Zealand’s Greenhouse Gas Inventory 1990−2022 does not use a multiplier.

International travel is divided by class of travel. Emissions vary by class because they are based on the number of people on a flight. Business class passengers use more space and facilities than economy class travellers. If everyone flew business class, fewer people could fit on the flight and therefore emissions per person would be higher.

7.6 Helicopters

This section provides emission factors for some commonly used helicopters in New Zealand. Business activities that require the use of helicopters might include entities involved in tourism, air transport, agricultural operations, or emergency services.

Table 44: Emission factors for helicopters

7.6.1 GHG inventory development

These emission factors can be used where the amount of fuel used is not known. Obtaining fuel data will provide a more accurate estimate of your carbon emissions. To calculate emissions from operating helicopters when only the number of operating hours is known. Applying the equation E = Q x F (section 2), this means:

E = emissions from the emissions source in kg CO2-e per year

Q = hours of operating time (hours)

F = emission factors for correlating helicopter type, from Table 44.

7.6.2 GHG inventory development

These emission factors can be used where the amount of fuel used is not known. Obtaining fuel data will provide a more accurate estimate of your carbon emissions.

To calculate emissions from operating helicopters when only the number of operating hours is known. Applying the equation E = Q x F (section 2), this means:

E = emissions from the emissions source in kg CO2-e per year

Q = hours of operating time (hours)

F = emission factors for correlating helicopter type, from Table 44

HELICOPTER USE: EXAMPLE CALCULATION

7.6.2 Emission factor derivation methodology

These emission factors were derived from the Swiss Federal Office of Civil Aviation’s (FOCA) Guidance on the Determination of Helicopter Emissions. This contains air emissions data (non-GHG) for one hour of flying time, including fuel consumption, for a range of helicopter models.This contains air emissions data (non-GHG) for one hour of flying time, including fuel consumption, for a range of helicopter models.

The one-hour emissions values are used, which assume a combination of rotations and cruise per flight-hour.

The fuel consumption (provided in kgs) was converted to litres using assumed densities of 0.804 kg per litre and 0.690 kg per litre, for Jet A1 and aviation gas respectively. Turbine engine helicopters are assumed to use Jet A1 while piston helicopters are assumed to use aviation gas. We then applied the Jet A1 and aviation gas emission factors from Transport fuels section above to determine the emission factor for one hour of operation.

We used the aircraft register on the New Zealand Civil Aviation Authority (CAA) website14 to identify the most commonly registered helicopter models in the country.

7.6.3 Assumptions, limitations and uncertainties

Obtaining the amount of fuel used for helicopter activities would provide a more accurate estimate of carbon emissions, than using this emission factor which is based on operating hours.

A number of factors will influence the accuracy of this emission factor for a given operating hour, such as the cruising speed, the take-off and approach, and the way the helicopter is being used.

Finally, if your entity has a helicopter model that is not provided here, you may wish to choose the model that seems to be the best fit. However, this approach will have limitations, due to variations that include engine operating power, and the size and number of engines.

7.7 Accommodation

Accommodation is an indirect (Scope 3) emissions source associated with business travel. The emission factors for hotel stays have been updated using factors from the 2023 edition of the Cornell Hotel Sustainability Benchmarking Index (CHSB) Index,15which provides data for the 2021 calendar year.

We obtained the emission factors from the M1 tab of the source spreadsheet, using the median values for all hotels. The factors are in CO2-e and are not available by gas type. For more information on the Cornell methodology, see the Hotel Sustainability Benchmarking Index 2023 guidance document.16

Note these emission factors are based on either AR4 or AR5 GWP values, depending on the country. The reason is some countries submit their emission factors to this study in terms of CO2-e, while other countries break it down into the three main GHG types. In the latter cases, the AR5 GWPs were applied.

The provision of these emission factors can be limited by the availability of data in different countries. If the factor for a certain country is not available in table 45, we recommend using factors from a previous edition of this guidance.

Table 45: Accommodation emission factors by unit (room per night)

7.7.1 GHG inventory development

To calculate emissions from accommodation during business trips, collect data on the number of nights and the country stayed in. Applying the equation E = Q x F ([section 2])(https://environment.govt.nz/assets/publications/Measuring-Emissions-2024/Measuring-emissions_Detailed-guide_2024_ME1829.pdf#page=20&zoom=100,109,76), this means:

E = emissions from the emissions source in kg CO2-e per year

Q = rooms per night

F = emission factors for the country stayed in from Table 45.

EXAMPLE CALCULATION

7.7.2 Assumptions, limitations and uncertainties

The Hotel Sustainability Benchmarking Index 2023 guidance document38 outlines the limitations of the study. These include:

• it is skewed towards upmarket and chain hotels, meaning the data may not be representative of the entire hotel industry, particularly the economy and midscale segments

• the results do not distinguish a property’s facilities, except for outsourced laundry services, which are taken into consideration. This means it is difficult to compare two hotels because some may contain distinct attributes (such as restaurants, fitness centres and swimming pools) while others do not

• the data have not been independently verified by a third-party provider.

Footnotes

  1. Lee, DS, Fahey, DW, Skowron, A, Allen MR, Burkhardt U, Chen Q, Doherty SJ, Freeman S, Forster PM, Fuglestvedt J, Gettelman A, De León RR, Lim LL, Lund MT, Millar RJ, Owen B, Penner JE, Pitari G, Prather MJ, Sausen R, Wilcox LJ. 2021. The contribution of global aviation to anthropogenic climate forcing for 2000 to 2018. Atmospheric Environment 244.↩︎

  2. Motor Vehicle Register: www.nzta.govt.nz/vehicles/how-the-motor-vehicle-register-affects-you/motorvehicle-registrations-dashboard-and-open↩︎

  3. Motor Vehicle Register: http://www.nzta.govt.nz/vehicles/how-the-motor-vehicle-register-affects-you/motor-vehicle-registrations-dashboard-and-open-data/↩︎

  4. New Zealand Transport Agency: www.transport.govt.nz/assets/Uploads/Data/NZVehicleFleet.xlsx.↩︎

  5. Te Manatū Waka Ministry of Transport: www.transport.govt.nz/statistics-and-insights/fleetstatistics/sheet/annual-fleet-statistic↩︎

  6. GHG Protocol Technical Guidance for Calculating Scope 3 Emissions: https://ghgprotocol.org/sites/default/files/standards_supporting/Chapter6.pdf.↩︎

  7. GHG Protocol Technical Guidance for Calculating Scope 3 Emissions: https://ghgprotocol.org/sites/default/files/standards_supporting/Chapter6.pdf.↩︎

  8. New Zealand Transport Agency, Passenger data, accessed September 2020: www.nzta.govt.nz/assets/userfiles/transport-data/PTPerformance.xlsx.↩︎

  9. The average fuel efficiency was based on Auckland Transport’s GHG inventory of 2022/23.↩︎

  10. The average fuel efficiency was based on Auckland Transport’s GHG inventory of 2022/23.↩︎

  11. Kerosene (ils.co.nz).↩︎

  12. 33 International Civil Aviation Organisation Calculator: www.icao.int/environmentalprotection/CarbonOffset/Pages↩︎

  13. https://archive.ipcc.ch/ipccreports/sres/aviation/121.htm#8223↩︎

  14. www.aviation.govt.nz/aircraft/aircraft-registration/aircraft-register-search/.↩︎

  15. https://ecommons.cornell.edu/bitstreams/3b5be73e-3c37-40a2-b124-430b8b697086/download.↩︎

  16. https://ecommons.cornell.edu/bitstreams/220e2386-fac7-4985-8825-a901176b161f/download.↩︎