Availability of CARB’s EMFAC2021 (v1.0.2) Model

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May 2, 2022

Availability of CARB’s EMFAC2021 (v1.0.2) Model

The California Air Resources Board (CARB) is officially releasing an updated version of the EMFAC2021 software to the public on Monday, May 2, 2022. This version will replace the current version (v1.0.1) that was previously released on April 30, 2021. This new version addresses a bug related to NOx idling exhaust emissions from newer heavy-duty trucks that are affected by the Heavy-Duty Omnibus regulation, and reflects the revocation of the Safer Affordable Fuel-Efficient or SAFE Vehicles Rule. In addition, an air conditioning correction factor for plug-in-electric vehicle CO running exhaust emissions has also been updated. These updates are also reflected on the EMFAC2021 web platform. The impacts of these updates are shown in details on CARB's MSEI website. The new version, along with the EMFAC2021 web platform, will be submitted to USEPA for approval.

Download EMFAC2021

The EMFAC2021 web platform allows users to download emissions data with default activity, produce emissions using custom activity inputs, the same as EMFAC’s Custom Activity (SG) model, and generate emission factors using user-defined ambient temperature and relative humidity for project level assessment (PL). In addition to the latest EMFAC2021 (v1.0.2) model, the EMFAC2017 (v1.0.3) web platform features still remain accessible to users.

EMFAC Web Platform

EMFAC2021 is the latest emission inventory model that CARB uses to assess emissions from on-road motor vehicles including cars, trucks, and buses in California, and to support CARB’s planning and policy development. This newest model reflects CARB’s current understanding of statewide and regional vehicle activities, emissions, and recently adopted regulations such as Advanced Clean Trucks (ACT) and Heavy Duty Omnibus regulations. It represents the next step forward in the ongoing improvement for EMFAC. More details about emissions calculation methodologies and data are summarized in the EMFAC2021 Technical Documentation, which was released in April 2021. Please join the MSEI email list to stay informed of future EMFAC developments or public webinars.


For more information or questions on EMFAC, please contact us at emfac@arb.ca.gov.