5  Purchased electricity, heat and steam emission factors

Purchased energy, in the form of electricity, heat or steam, is an indirect (Scope 2) emission. This section also includes transmission and distribution losses for purchased electricity, which is an indirect (Scope 3) emissions source.

Note that both the emission factor for purchased electricity and the emission factor for transmission and distribution line losses align with the definitions in the GHG Protocol Corporate Standard.

In this guide, we have included a time series of historic electricity emission factors based on annual and quarterly periods. The quarterly time series extends back to the past three years, and the annual time series extends back to 2010. There is also an equivalent annual time series for transmission and distribution losses.

The guide provides information on reporting imported heat and steam and geothermal energy. It does not provide emission factors for these categories as they are unique to a specific site. Users could liaise directly with their supplier of the imported heat, steam, or geothermal energy, for supplier specific emissions intensities suitable for use in the entity inventory.

5.1 Overview of emission factor changes from 2025 to 2026

Table 5.1: Summary of changes to purchased energy emission factors
Section Total EFs EFs added EFs removed EFs changed Explanation for change
Purchased Electricity 32 7 4 21 Changes are due to updated purchased electricity source data, including added 2010 and 2011 annual rows for time-series coverage and updated quarterly data.
Transmission and distribution losses 14 1 0 13 Changes are due to updated electricity and gas transmission and distribution loss source data, with purchased electricity changes flowing through to electricity T&D factors.

For detailed information on the emission factor changes, download the Emission factor changes CSV file from Appendix G.

5.2 Indirect Scope 2 emissions from purchased electricity from the New Zealand grid – using the location-based method

This guide applies to electricity purchased from a supplier that sources electricity from the national grid (i.e, purchased electricity consumed by end users). It does not cover on-site, self-generated-electricity.

The grid-average emission factor best reflects the carbon dioxide equivalent emissions associated with the generation of a unit of electricity purchased from the national grid in New Zealand. We recommend the use of the emission factors in Table 5.2 and Table 5.3 for all electricity purchased from the national grid, apart from when a market-based method is being used.

The emission factor accounts for the emissions from fuel combustion at thermal power stations (ie, power stations which generate electricity by burning fossil fuels) and fugitive emissions from the generation of geothermal electricity.

The emission factor for purchased grid-average electricity does not include transmission and distribution losses. A separate average emission factor for this as an indirect (Scope 3) emission source is in Section 5.3

The provided emission factors are an average for the whole of New Zealand for a given quarter or year. The actual emissions produced for a given unit of electricity may differ depending on factors such as the time of year, time of day and geographical area.

Using quarterly emission factors accounts for the high seasonal variation seen in electricity emission factors. This variation is generally a result of the higher proportion of fossil-based electricity generation typically used in the winter months. Therefore, using an annual emission factor may over or underestimate your entity’s GHG emissions.

Detailed additional guidance on reporting electricity emissions is available in the GHG Protocol Scope 2 Guidance.

As with the fuels for stationary combustion emission factors, the electricity emission factors do not incorporate emissions associated with the extraction, production and transport of the fuels burnt to produce electricity.

The emission factors for the annual average purchased electricity based on annual generation from the New Zealand grid is in Table 5.2.

Table 5.2: Emission factors for purchased grid-average electricity – annual average
Emissions Source Unit kg CO₂–e/unit CO₂/unit (kg CO₂–e) CH₄/unit (kg CO₂–e) N₂O/unit (kg CO₂–e)
Annual Averages
Electricity Used – 2010 kWh 0.150551 0.146708 0.00367289 0.00017044
Electricity Used – 2011 kWh 0.13872 0.13476 0.00377322 0.000187115
Electricity Used – 2012 kWh 0.172972 0.168685 0.00398084 0.000306438
Electricity Used – 2013 kWh 0.146071 0.141639 0.00422992 0.000202257
Electricity Used – 2014 kWh 0.121976 0.117495 0.00432532 0.000155005
Electricity Used – 2015 kWh 0.116715 0.112041 0.00453395 0.000140686
Electricity Used – 2016 kWh 0.0914997 0.0873165 0.00411009 0.0000730725
Electricity Used – 2017 kWh 0.103105 0.0992181 0.00380078 0.0000856557
Electricity Used – 2018 kWh 0.0977256 0.0942051 0.00340028 0.000120258
Electricity Used – 2019 kWh 0.110329 0.107121 0.00303602 0.000171851
Electricity Used – 2020 kWh 0.121468 0.118376 0.00290034 0.000191555
Electricity Used – 2021 kWh 0.123399 0.120322 0.00282183 0.000255036
Electricity Used – 2022 kWh 0.0817278 0.0788813 0.00275254 0.0000939435
Electricity Used – 2023 kWh 0.0765687 0.074061 0.00243148 0.0000762189
Electricity Used – 2024 kWh 0.0993596 0.096777 0.00239406 0.000188616
Electricity Used – 2025 kWh 0.0786625 0.0761325 0.00240719 0.000122795

The emission factors for the calendar quarters (quarter end) for 2023–2025 purchased electricity from the New Zealand grid are in Table 5.3.

Table 5.3: Emission factor for purchased grid-average electricity – calendar quarters
Emissions Source Unit kg CO₂–e/unit CO₂/unit (kg CO₂–e) CH₄/unit (kg CO₂–e) N₂O/unit (kg CO₂–e)
Quarterly Averages
Electricity Used – Mar–2023 kWh 0.0767607 0.0740866 0.00261876 0.000055305
Electricity Used – Jun–2023 kWh 0.0529497 0.0508473 0.00207736 0.0000250221
Electricity Used – Sep–2023 kWh 0.100358 0.0977978 0.00245478 0.00010526
Electricity Used – Dec–2023 kWh 0.0742611 0.0715502 0.00259396 0.000116933
Electricity Used – Mar–2024 kWh 0.0880302 0.0855611 0.00235738 0.000111765
Electricity Used – Jun–2024 kWh 0.134587 0.131975 0.00229824 0.000314382
Electricity Used – Sep–2024 kWh 0.130384 0.127607 0.00248778 0.000289319
Electricity Used – Dec–2024 kWh 0.0383377 0.0358888 0.00243034 0.000018561
Electricity Used – Mar–2025 kWh 0.115912 0.112967 0.00273997 0.000205025
Electricity Used – Jun–2025 kWh 0.108492 0.105982 0.00230793 0.000202353
Electricity Used – Sep–2025 kWh 0.066386 0.0639363 0.00237022 0.0000794735
Electricity Used – Dec–2025 kWh 0.0272654 0.025013 0.00223889 0.0000135055

5.2.1 GHG inventory development

To calculate the emissions from purchased electricity, first collect data on the quantity of electricity used during the period in kilowatt hours (kWh), then multiply this by the emission factor. Applying the equation E = Q x F this means:

  • E = emissions from the emissions source in kg CO2-e within the reporting period
  • Q = electricity used during the reporting period (kWh)
  • F = emission factors from Table 5.2 or Table 5.3.

All entities across sectors typically report emissions using data on the amount of electricity used during the reporting period. Quantified units of electricity consumed are preferable.

5.2.1.1 PURCHASED ELECTRICITY: EXAMPLE CALCULATION

An entity uses 800,000 kWh of electricity in the 2024 reporting period. Its indirect (Scope 2) emissions from electricity are:

Example calculation of purchased electricity emissions
Gas Calculation Emissions (kg CO₂-e)
CO₂ emissions 800,000 x 0.0761325 kg CO₂-e per kWh 60,900 kg CO₂-e
CH₄ emissions 800,000 x 0.00240719 kg CO₂-e per kWh 1,930 kg CO₂-e
N₂O emissions 800,000 x 0.000122795 kg CO₂-e per kWh 98.2 kg CO₂-e
Total CO₂-e emissions 800,000 x 0.0786625 kg CO₂-e per kWh 62,900 kg CO₂-e

Note: Numbers may not add due to rounding.

5.2.2 Emission factor derivation methodology

MBIE calculated the generation emission factors based on emissions from the generation of public electricity and the amount of electricity generated. The generation emission factors are calculated as a national average for each quarter or year.

5.2.3 Assumptions, limitations and uncertainties

Using an annual average grid emission factor for electricity will inevitably introduce a certain level of inaccuracy, as the generation mix varies depending on your geographical location, by time of day and time of year.

We derived the emission factors in Table 5.2 and Table 5.3 for purchased electricity from generation data rather than consumption data. This emission factor does not account for the emissions associated with the electricity lost in transmission and distribution on the way to the end user. Table 5.4 contains the emission factors for transmission and distribution line losses.

5.3 Transmission and distribution losses for electricity

The emission factor for transmission and distribution line losses accounts for the additional electricity generated to make up for electricity lost in the transmission and distribution network. Under the GHG Protocol, end users should report emissions from electricity consumed from a transmission and distribution system as an indirect (Scope 3) emission source. Electricity and distribution companies should however report these losses as indirect (Scope 2) emissions.1.

Table 5.4 shows the emission factors for transmission and distribution losses from the national grid.

Table 5.4: Transmission and distribution losses for electricity consumption
Emissions Source Unit kg CO₂–e/unit CO₂/unit (kg CO₂–e) CH₄/unit (kg CO₂–e) N₂O/unit (kg CO₂–e)
Electricity Consumption
2012 kWh 0.0130686 0.0127447 0.000300766 0.0000231524
2013 kWh 0.0107768 0.0104498 0.000312074 0.000014922
2014 kWh 0.00871749 0.00839728 0.000309127 0.0000110781
2015 kWh 0.00831389 0.0079809 0.000322963 0.0000100214
2016 kWh 0.0066904 0.00638452 0.000300527 0.00000534301
2017 kWh 0.00750829 0.00722527 0.000276781 0.00000623763
2018 kWh 0.00708579 0.00683052 0.000246544 0.00000871956
2019 kWh 0.00816851 0.00793101 0.00022478 0.0000127234
2020 kWh 0.00906589 0.00883512 0.00021647 0.0000142969
2021 kWh 0.00932754 0.00909496 0.000213298 0.0000192779
2022 kWh 0.00614709 0.005933 0.00020703 0.00000706588
2023 kWh 0.00573639 0.00554851 0.000182162 0.00000571018
2024 kWh 0.00752331 0.00732776 0.000181273 0.0000142816
2025 kWh 0.00595616 0.0057646 0.000182268 0.00000929777

5.3.1 GHG inventory development

To calculate the emissions from transmission and distribution losses for purchased electricity, collect data on the quantity of electricity used during the period in kilowatt hours (kWh) and multiply this by the emission factor. Applying the equation E = Q x F this means:

  • E = emissions from the emissions source in kg CO2-e within the reporting period
  • Q = electricity used during the reporting period (kWh)
  • F = emission factors from Table 5.4.

5.3.1.1 TRANSMISSION AND DISTRIBUTION LOSSES: EXAMPLE CALCULATION

An entity uses 800,000 kWh of electricity in the 2024 reporting period. Its indirect (Scope 3) emissions from transmission and distribution losses for purchased electricity are:

Example calculation of emissions from Transimission and Distribution Losses for purchased electricity
Gas Calculation Emissions (kg CO₂-e)
CO₂ emissions 800,000 x 0.0057646 kg CO₂-e per kWh 4,610 kg CO₂-e
CH₄ emissions 800,000 x 0.000182268 kg CO₂-e per kWh 146 kg CO₂-e
N₂O emissions 800,000 x 0.00000929777 kg CO₂-e per kWh 7.44 kg CO₂-e
Total CO₂-e emissions 800,000 x 0.00595616 kg CO₂-e per kWh 4,760 kg CO₂-e

Note: Numbers may not add due to rounding.

Alternatively, if your electricity provider gives a breakdown of the transmission and distribution losses this consumption data can be multiplied by a grid-average electricity emission factor from Table 5.2.

5.3.2 Emission factor derivation methodology

Emission factors provided directly by MBIE, which uses actual transmission and distribution losses data, resulting in the emission factors more accurately reflect the actual losses on the electricity grid.

5.3.3 Assumptions, limitations and uncertainties

This emission factor covers grid-average electricity purchased by an end user. As with all emission factors for purchased electricity, we calculated those for transmission and distribution line losses as a national average.

As it is an average figure, the emission factor makes no allowance for distance from off-take point, or other factors that may vary between individual consumers.

This emission factor does not incorporate the emissions associated with the extraction, production and transport of the fuels burnt to produce the electricity.

5.4 Imported heat and steam

Entities that have a specific heat or steam external energy source (such as a district heating scheme) can calculate emissions using an emission factor specific to that scheme. This should be available from the owner of the external energy source.

5.5 Geothermal energy

Entities that have their own geothermal energy source can calculate emissions separately using a unique emission factor. Noting carbon emissions from geothermal power stations can be variable over time, this would consider factors such as the measured CO2 output from the production wells and the CO2 output at the surface, along with how the water by-product is used, for example, as industrial process heat.

Depending on the steam coming from the borehole, there may or may not be emissions associated with this energy type.

  1. GHG Protocol Scope 2 Guidance: https://ghgprotocol.org/sites/default/files/standards/Scope%202%20Guidance_Final_Sept26.pdf↩︎