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National Clean Diesel Campaign (NCDC)

Working Together for Cleaner Air

State & Local Toolkit - Evaluation


Regardless of the metrics used, reporting results is important to tracking your effectiveness. There are many ways to evaluate Clean Diesel Programs including the number of engines retrofitted, hours of idling reduced, number of partners engaged, and total funds granted. However, the quantity of emissions reduced is the most common means of evaluation. The information here discusses how to calculate emissions reductions, records that should be kept, credits that might be claimed, and reports that should be written to document the performance of the program.

You will need Adobe Reader to view some of the files on this page. See EPA's PDF page to learn more.

Record Keeping

Measuring results and verifying clean diesel investments require good tracking and reporting mechanisms. Contracts and grants commonly require reporting diesel emissions reductions.

California’s Carl Moyer program does a pre- and post-inspection for its grant-funded activities and requires annual reports from grantees. The Texas Emissions Reduction Plan (TERP) and most EPA diesel emission reduction grants require quarterly and final reports.

Typical data required for calculating emissions reductions and cost effectiveness of clean diesel projects include:

  • Vehicle type and model
  • Engine model year
  • Year of retrofit
  • Gross vehicle weight rating (GVWR) (onroad engines) or horsepower (nonroad engines)
  • Type of retrofit technology
  • Type and quantity of emissions reduced (EPA Verified Technologies List)
  • Fuel type
  • Usage information (fuel consumption, mileage, hours of operation)
  • Cost of technology and installation


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Emissions Inventory & Reductions Quantification

For a broad look at air emissions sources and inventories, organizations can use the National Emissions Inventory. EPA has developed emission inventory models specifically for air pollutants from mobile sources. For specific questions about the models listed below contact: mobile@epa.gov or nonroad@epa.gov.

Note that California uses a different set of models for its regulatory programs. You will find these at the California Air Resource Board's Mobile Source Emissions Inventory Program. Exit EPA Disclaimer

These models can be used to evaluate the effectiveness of retrofits and other strategies to reduce harmful emissions.

Diesel Emissions Quantifier

The Diesel Emissions Quantifier (DEQ) is a user-friendly, interactive tool that can estimate the emission reductions and cost effectiveness of clean diesel projects. This quantifier is useful for project-level calculations, but should not be used for formal State Implementation Plan (SIP) or conformity processes.

SmartWay Transport Partnership

SmartWay tracking systems allows a company to quantify the environmental performance of its fleet operations. They are used to become a SmartWay Partner. Partnership types:

Technical EPA Models

Users with air quality modeling experience may wish to use EPA’s more technical models for quantifying the benefits of retrofit projects.

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Claiming Emissions Credits in Air Quality Plans

Some entities are also interested in claiming emissions credits in air quality efforts such as State Implementation Plans (SIPs) and conformity. EPA has provided guidance for claiming emissions credit for diesel emissions reductions.

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Reporting Program Results

Reporting on program successes and challenges is an important component of demonstrating accountability, good governance, and program sustainability. The examples below provide models to publicize program activities.

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