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Waste Reduction Model (WARM)

WARM Quick Finder

Model History ReCon User Guide WARM FAQs
ReCon Tool Solid Waste Management and Greenhouse Gases WARM Worksheet
ReCon Online Source Reduction vs. Recycling WARM User Guide
WARM Materials Definitions
What's New?
More Information about WARM

ReCon and WARM were developed for purchasers and waste managers, respectively. ReCon calculates the benefits of alternative recycled content purchasing decisions. WARM, on the other hand, calculates the benefits of alternative end-of-life waste management decisions. Both tools calculate the benefits of an alternative scenario versus a business-as-usual scenario.

The WARM and ReCon tools are based on a life-cycle approach, which reflects emissions and avoided emissions upstream and downstream from the point of use. As such, the emission factors provided in these tools provide an account of the net benefit of these actions to the environment. This life-cycle approach is not appropriate for use in inventories because of the diffuse nature of the emissions and emission reductions within a single emission factor.

NEW MODEL VERSION: Updated June 2014

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 waste management practices. WARM is available both as a Web-based calculator and as a Microsoft Excel spreadsheet (.zip) (586 Kb). The Excel-based version of WARM offers more functionality than the Web-based calculator.

WARM calculates and totals GHG emissions of baseline and alternative waste management practices—source reduction, recycling, combustion, composting, and landfilling. The model calculates emissions in metric tons of carbon equivalent (MTCE), metric tons of carbon dioxide equivalent (MTCO2E), and energy units (million BTU) across a wide range of material types commonly found in municipal solid waste (MSW). For information on the data and methodologies behind the calculations, please see the model documentation.

WARM is periodically updated as new information becomes available and new material types are added. Users may refer to the model history to better understand the differences among various versions of WARM. WARM was last updated June, 2014.

WARM now recognizes 50 material types, which are presented in the table below; their emission factors are available for viewing in units of metric tons of carbon dioxide equivalent (MTCO2E) or metric tons of carbon equivalent (MTCE). Note that the emission factors represent the GHG emissions associated with managing 1 short ton of MSW in the manner indicated. GHG savings should be calculated by comparing the emissions associated with the alternative scenario with the emissions associated with the baseline scenario, as opposed to simply multiplying the quantity by an emission factor. For instance, the GHG savings of recycling 1 short ton of aluminum cans instead of landfilling them would be calculated as follows:

(1 short ton × -9.11 MTCO2E/short ton) - (1 short ton × 0.04 MTCO2E/short ton) = -9.15 MTCO2E

For information on the definition of each of the WARM material types as well as data source and year of underlying life-cycle data, please see the WARM materials definitions list. For information on using WARM emission factors for materials and pathways not in WARM, please see the guide to using proxies in WARM (PDF) (11 pp, 654 KB).

Material Types Recognized by WARM
Aluminum Cans Fruits and Vegetables* Mixed Recyclables
Aluminum Ingot Glass Newspaper
Asphalt Concrete Grains* Office Paper
Asphalt Shingles Grass Personal Computers
Branches HDPE PET
Bread* LDPE Phonebooks
Carpet Leaves PLA
Clay Bricks LLDPE PP
Concrete Magazines / Third-Class Mail PS
Copper Wire Medium Density Fiberboard PVC
Corrugated Cardboard Mixed Metals Steel Cans
Dairy Products* Mixed MSW Textbooks
Dimensional Lumber Mixed Organics Tires
Drywall Mixed Paper (general) Vinyl Flooring
Fiberglass Insulation Mixed Paper (primarily from offices) Wood Flooring
Fly Ash Mixed Paper (primarily residential) Yard Trimmings
Food Waste (non-meat) Mixed Plastics  
* For simplicity, these factors are included only in the Excel version of WARM.
Using WARM

NEW VERSION: Updated June 2014

WARM is available in a Web-based calculator format and as a Microsoft Excel spreadsheet (.zip) (586 Kb). The WARM User's Guide will help you get up and running with the WARM software.

To download and open the Excel version of WARM, follow the directions below:

To download the zip file:

> Save this file (WARM.zip 586 kb WinZip file) to your hard drive.
> Open it and extract the warm.xls file to your hard drive.

The installed program is a Microsoft Excel spreadsheet application. After you have installed the program, you may run the application: Version 13 of WARM is compatible with Excel versions 2003, 2007 and 2010.

Using Microsoft Excel 5.0
> To run the WARM program, open the warm.xls file.
> Select the "Read Only" option.
> You may then begin using the WARM application.
Using Microsoft Excel 97 or higher
> To run the WARM program, open the warm.xls file.
> Select the "Enable Macros" option.
> You may then begin using the WARM application.

IMPORTANT: In the latest versions of WARM (Versions 12 and 13), there are no macros within the tool. For previous versions of WARM (Version 11 and earlier), in order for WARM to function, your Excel settings must be set to permit the use of macros. For instructions on adjusting your security settings and enabling macros, please refer to the WARM User's Guide.

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