Community Modeling and Analysis System


Brief Description

CoST (Control Strategy Tool) allows users to estimate the emission reductions and costs associated with future-year control scenarios, and then to generate emission inventories with the control scenarios applied. CoST is a component of the Emissions Modeling Framework (EMF), which is currently used by EPA to solve many of the long-standing complexities of emissions modeling. Emissions modeling is the process by which emissions inventories and other related information are converted to hourly, gridded, chemically speciated emissions suitable for input to an air quality model. The EMF supports the management and quality assurance of emissions inventories and emissions modeling-related data, and also the running of SMOKE to develop air quality model inputs.


CoST was developed primarily for performing Regulatory Impact Analyses (RIAs) for National Ambient Air Quality Standards (NAAQS). As part of the RIA development process, CoST allows EPA to identify additional emissions controls that could be applied by states and EPA to bring areas into attainment, and to estimate the emissions reductions and costs of these additional controls.


CoST tracks information about control measures, their costs, and the types of emissions sources to which they apply.

Supports preparation and analysis of future year emissions control strategies for point (primarily non-EGU), area, and mobile sources.

CoST is built on top of Control Measures Database (CMDB), a database of current information about control technologies and practices that are available to reduce emissions, the source categories to which they apply, the expected control efficiencies, and their estimated costs.

CoST is an extensible software system that provides several types of algorithms for developing control strategies:

  • Maximum Emissions Reduction
  • Multi-Pollutant Maximum Emissions Reduction
  • Least Cost
  • Least Cost Curve

Control strategy results can be exported to comma-separated-values (CSV) files, SMOKE-formatted inventory files, Google Earth-compatible (.kmz) files, or Shapefiles. The results can also be viewed in a graphical table that supports sorting, filtering, and plotting.

CoST is a component of the U.S. EPA's Emissions Modeling Framework (EMF), a client-server Java application and a PostgreSQL ( database that stores information related to emissions modeling, including emissions inventory datasets and the CMDB.

CoST reports the emissions reductions and costs associated with the co-impacts of a selected group of control measures on other pollutants.

Recent Updates

Full Release Notes

Updates in v4.1

  • Strengthen password requirements including increasing the minimum length to 12 characters and requiring the password to include numbers or symbols
  • Automatically disable accounts after 5 failed login attempts
  • Add options for administrators to disable accounts, see failed login attempts, and see when passwords were last updated

Updates in v4.0

  • Added equation type 21 for use by non-EGU SO2 control measures
  • Added matching by region code and facility ID to temporal allocation functionality
  • Updates to core EMF for better accessibility

Updates in v3.10

  • Enhancements to keyboard navigation and screen reader compatibility

Updates in v3.9

  • Update design capacity checks in cost equations to check that values are greater than 0.1 MW/hr rather than just greater than 0
  • Add design capacity check to equation type 2a to be consistent with other equation type 2 variants
  • Check for spaces in filenames when trying to upload or import files

Updates in v3.8

  • Log inventory sources with >= 100% control and non-zero emissions in the Strategy Messages dataset
  • Update calculation of projected inventory percent reduction for add-on controls
  • Update check for existing control at >= 100% when considering replacements in PFYI strategy
  • Add new cost equation type 2c based on existing type 2 with design capacity in HP

Updates in v3.7

  • Fix end condition for least cost narrowing algorithm
  • Add option to include dataset_id column when exporting flexible format datasets from control strategies
  • Update naming for combined strategy detailed results file to use control strategy name

History of CoST/EMF

The Control Strategy Tool was developed as a replacement for the AirControlNET (ACN) software tool which is no longer supported by EPA. It was determined in 2006 that it was an appropriate time to replace the ACN software with newer software that could provide improved effectiveness, functionality, and transparency to support current and upcoming needs. A prototype version of the Control Strategy Tool was developed in 2006 and a fully functional version was developed in 2008. The tool has the functionality of AirControlNET but with added capabilities, including:

  • The ability to insert emissions inventories almost seamlessly from the Emissions Modeling Framework (EMF)
  • The ability to insert new control measure data
  • Easier for users to track their analyses and output
  • Quality assurance (QA) steps provided for identifying errors in emissions and control measure data
CoST Flow Chart

Latest Version: CoST/EMF version 4.1



Previous Documentation

Online Resources

System Requirements

O/S Windows, Linux, Mac
Memory 1024 Mb RAM
Software All needed CoST components are contained in the distribution package.