Solid Waste Management and Greenhouse Gases

NEW MODEL DOCUMENTATION VERSION: Updated March 2015

Documentation for Greenhouse Gas Emission and Energy Factors Used in the Waste Reduction Model (WARM)

EPA created the Waste Reduction Model (WARM) to help solid waste planners and organizations track and voluntarily report greenhouse gas (GHG) emissions reductions from several different materials management practices. WARM calculates and totals the relative GHG emission and energy impacts of baseline and alternative materials management practices–source reduction, recycling, combustion, composting, and landfilling–using emission factors that EPA has developed based on a materials life-cycle approach. WARM emission factors are also used in other EPA tools, including the Recycled Content (ReCon) Tool, Individual Waste Reduction Model (iWARM), SMART BET, and the Greenhouse Gas Equivalency Calculator.

The documentation provided here explains the data, methods, and calculations behind the WARM emission factors.

This documentation is the next stage in evolution of the report most recently titled Solid Waste Management and Greenhouse Gases: A Life-Cycle Assessment of Emissions and Sinks, 3rd Edition, published in 2006. The second edition was published in 2002, while the first edition, titled Greenhouse Gas Emissions from Management of Selected Materials in Municipal Solid Waste, was published in 1998.

The current documentation explains the calculation of emission factors by material type, or group of materials, arranged into individual chapters. EPA also provides chapters addressing each specific materials management practice available in WARM, along with an introductory chapter, a glossary, and additional chapters on special topics like forest carbon sequestration and energy factors. This chapter-based format - first introduced in 2010 - provides more detailed and up-to-date information about the WARM emission factors than was available in the previous report format. In addition, several Background Documents are available that provide additional useful information pertaining to the WARM emission factors.

EPA has added several new materials to WARM and continues to improve upon the modeling of materials management pathways. For more information about changes since the last edition of the documentation, please see the chapter on Recent Updates in WARM.

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

Documentation

Documentation for Greenhouse Gas Emission and Energy Factors Used in the Waste Reduction Model (WARM) (PDF, 416 pp, 10.60 MB)

The WARM documentation was created for EPA by ICF International..

Background Documents

Additional Material-Specific Information

Background Document for Life-Cycle Greenhouse Gas Emission Factors for Clay Brick Reuse and Concrete Recycling (PDF, 21 pp, 775 KB)

Background Document for Life-Cycle Greenhouse Gas Emission Factors for Fly Ash Used as a Cement Replacement in Concrete (PDF, 17 pp, 585 KB)

Background Document for Life-Cycle Greenhouse Gas Emission Factors for Carpet and Personal Computers (PDF, 57 pp, 346 KB)

Background Document for Life-Cycle Greenhouse Gas Emission Factors for Copper Wire (PDF, 16 pp, 81 KB)

Background Document for Life-Cycle Greenhouse Gas Emission Factors for Scrap Tires (PDF, 8 pp, 47 KB)

Landfilling and Landfill Carbon Storage

Levis, J. and Barlaz, M.A. 2014. Landfill Gas Monte Carlo Model Documentation and Results. June 18, 2014. (PDF, 37 pp, 625 KB)

ICF. 2010. "Landfill Carbon Storage in EPA's Waste Reduction Model." October 27, 2010. (PDF, 2 pp, 185 KB)

ICF. 2009. "WARM component-specific decay rate methods."Memorandum from ICF International to United States Environmental Protection Agency. October 30, 2009. (PDF, 16 pp, 192 KB)

Barlaz M.A., 2008. "Corrections to Published Carbon Storage Factors for Mixed Municipal Waste". Memorandum to Parties Interested in Carbon Sequestration from Municipal Solid Waste. October 27, 2008.

ICF. 2008. "Revised Data for Landfill Carbon Storage in Yard Trimmings and Coated Paper, and Implications for Waste Management GHG Emission Factors and US GHG Inventory." Memorandum from ICF Consulting to United States Environmental Protection Agency. April 21, 2008. (PDF, 6 pp, 59 KB)

ICF. 2005. "Revised Landfilling Emission Factors based on New WOODCARB Inputs - Errata to May 6, 2005 Memo ," Memorandum from ICF Consulting to United States Environmental Protection Agency. August 1, 2005. (PDF, 2 pp, 52 KB)

ICF. 2005. "Revised Landfill Carbon Storage Factor and Net Emission Factor for Leaves based on New Experimental Results," Memorandum from ICF Consulting to United States Environmental Protection Agency. July 27, 2005. (PDF, 4 pp, 53 KB)

ICF. 2005. "Revised Landfilling Emission Factors Based on New WOODCARB Inputs." Memorandum from ICF Consulting to United States Environmental Protection Agency. May 6, 2005. (PDF, 6 pp, 93 KB)

Barlaz, M.A. 1997. "Biodegradative Analysis of Municipal Solid Waste in Laboratory-Scale Landfills ," EPA 600/R-97-071. (PDF, 6 pp, 31 KB)

ICF. 1995. "Work Assignment 239, Task 2: Carbon Sequestration in Landfills ," Memorandum from ICF Consulting to United States Environmental Protection Agency, Exhibit 2-A, column "O." (PDF, 8 pp, 51 KB)

Forest Carbon, Paper, and Wood

ICF. 2010. "Forest Carbon Storage in EPA's Waste Reduction Model." October 27, 2010. (PDF, 2 pp, 160 KB)

ICF. 2006. "Background Document on the Effect of Paper Recycling on Forest Carbon." Febuary 27, 2006. (PDF, 10 pp, 79 KB)

EDF. 1995. "Paper Task Force Recommendations for Purchasing and Using Environmentally Preferable Paper: Final Report of the Paper Task Force." Environmental Defense Fund (New York, NY), 245pp. (PDF, 249 pp, 3.2 MB)

Background Data

U.S. EPA. 1998a. Greenhouse Gas Emissions From Management of Selected Materials in Municipal Solid Waste . Background Document A: A Life Cycle of Process and Transportation Energy for Eight Different Materials . United States Environmental Protection Agency, prepared by Franklin Associates, Ltd. (PDF, 94 pp, 4.4 MB)

U.S. EPA. 1998b. Greenhouse Gas Emissions From Management of Selected Materials in Municipal Solid Waste . Background Document A, Attachment 1: A Partial Life Cycle Inventory of Process and Transportation Energy for Boxboard and Paper Towels . United States Environmental Protection Agency, prepared by Franklin Associates, Ltd. (PDF, 46 pp, 2.4 MB)

U.S. EPA. 1998c. Greenhouse Gas Emissions From Management of Selected Materials in Municipal Solid Waste. Background Document B: Methodology for Estimating the Amounts and Types of Energy Consumed in Raw Materials Acquisition and Manufacturing of Eight Different Materials. United States Environmental Protection Agency, prepared by the Tellus Institute. (PDF, 74 pp, 3.6 MB)

U.S. EPA. 1998d. Greenhouse Gas Emissions From Management of Selected Materials in Municipal Solid Waste . Background Document C: Review Process for the Report . United States Environmental Protection Agency. (PDF, 3 pp, 23 KB)

U.S. EPA. 1998e. Greenhouse Gas Emissions From Management of Selected Materials in Municipal Solid Waste. Background Document D: Comment-Response Document. United States Environmental Protection Agency, prepared by ICF Consulting. (PDF, 63 pp, 221 KB)

If you need additional information about the Documentation and Background Documents, please email orcrWARMquestions@epa.gov.