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The Vehicle Emissions Prediction Model (VEPM) has been developed by Waka Kotahi NZ Transport Agency and Auckland Council to predict emissions from vehicles in the New Zealand fleet under typical road, traffic and operating conditions. The model provides estimates that are suitable for air quality assessments and regional emissions inventories.

Since its release in 2008, VEPM has been successfully used in Auckland and around New Zealand to estimate vehicle emissions in air quality assessments for road projects. An important feature of the model is the ability to estimate changes to vehicle emissions in future years (out to 2050).

VEPM is a password protected Excel spreadsheet which is publicly available upon request from Waka Kotahi. A summary of the previous and current versions of VEPM are provided below.

  1. To request the password, please email environment@nzta.govt.nz with Vehicle Emissions Prediction Model in the subject line.
  2. To download the spreadsheet, click on the link below.

Privacy statement

When you email us to request the password for the VEPM, we collect your name and email address. These details will be added to a mailing list that is only used to let you know about VEPM updates, for example when we make a change to the tool, or when we conduct surveys regarding improving the tool. You can request access to and correction of that information at any time by emailing environment@nzta.govt.nz.

If you do not wish to receive emails about the VEPM, please tell us; and remember to check this webpage regularly for updates and changes to the VEPM tool. 

View our website Privacy information(external link)

Disclaimer

Waka Kotahi does not represent or endorse the information, content, presentation or accuracy of this vehicle emissions prediction model and its contents.

Read the full Disclaimer(external link)

Version Notes
VEPM 5.1 Previous version of the model released in 2012.
VEPM 5.2 Beta version of model, which was not formally released but has been made available on specific request. This version includes updates based on vehicle kilometres travelled (VKT) data from the Vehicle Fleet Emission Model (VFEM) provided by Ministry of Transport. 
VEPM 5.3 Changes from the previous VEPM 5.1 released in 2012. This version incorporates nitrogen dioxide, speeds for light vehicles up to 110km/h, updates to the emission standard introduction date and country of origin assumptions, updated emissions factors for Euro 5, Euro 6 and Euro V based on COPERT, and addition of Euro VI category.
VEPM 6.0 Changes to the previous version VEPM 5.3 released in 2017 include: Updating the fleet and extending VEPM to 2050, creating separate categories in VEPM for light duty hybrid, plug-in hybrid and electric vehicles, adding a new category for electric heavy-duty trucks and buses, updating all Euro emission factors with emission factors from the latest version of COPERT, incorporating new Euro 6 emission factors for passenger and light commercial vehicles, updating the method for calculation of tailpipe CO2 and updating brake and tyre wear emission factors.
VEPM 6.1

Changes to the previous version VEPM 6.0 released in 2019 include: changes to significantly reduce bulk run processing times and rationalise the spreadsheet model, replacing all existing Euro emission factors with emission factors from the latest version of COPERT, incorporating articulated truck emission factors and estimated VKT into VEPM, incorporating bus emission factors into VEPM and incorporating New Zealand real world fuel consumption correction factors for diesel passenger cars and diesel light commercial vehicles.

VEPM 6.2

Current version of the model [ZIP, 22 MB]

Changes to the previous version VEPM 6.1 released in 2020 include:

  • Updating the fleet profile based on updated vehicle kilometres travelled (VKT) data from the Vehicle Fleet Emission Model (VFEM3) provided by Ministry of Transport
  • Revising the assumed date of introduction of Euro 6/VI standards in VEPM
  • Improving the assumptions in VEPM to split heavy commercial vehicle VKT between rigid and articulated truck categories
  • Providing methane (CH4) and nitrous oxide (N2O) emission factors and calculation of carbon dioxide equivalent (CO2-e) emission factors
  • Incorporating updated emission factors from the latest version of COPERT (the EU standard vehicle emissions calculator)
  • Updating degradation factors for light duty vehicle carbon monoxide (CO) and nitrogen oxides (NOX) emissions
  • Updating light duty gradient correction factors.

Waka Kotahi has prepared a VEPM user guide which describes the modelling process and the background for the VEPM method. The VEPM user guide and a summary of the development of VEPM are provided below. Additional supporting technical information can be found in the research reports which are referenced from the user guide.

For further information contact environment@nzta.govt.nz.