The availability of updated information has necessitated updates to the emission factors used in WARM and the ReCon tool. Thus, the report that provides the basis for the factors used in the tools, Solid Waste Management and Greenhouse Gases: A Life-Cycle Assessment of Emissions and Sinks (2nd Edition) has become somewhat outdated. While the methodology is basically unchanged, the underlying data and assumptions have been revised and updated several times. Since some companies and waste managers have used older versions of the tool, the purpose of this page is to explain the changes incorporated with each version.
Below is a brief chronology of changes made to WARM and the ReCon tool. Starting with the most recent edition, brief summaries of changes and updates since the previous version are provided below. The objective is to provide users with a transparent picture of the evolution of the tools and to provide context for comparisons of results obtained from different versions of ReCon. Users can browse the supporting documentation for these changes in the Background Documents for Solid Waste Management and GHG Report.
WARM
WAste Reduction Model (WARM) Version 7
This is the latest edition of the model available to the public. It was released in August 2005 and contains several updates and improvements. Copper wire was added as a new material type providing additional resolution to the metals category. The latest statistics on national average electricity generation fuel consumption were added along with recent research on landfill methane generation and carbon sequestration associated with organic matter; the retail transportation component of the life-cycle was also added to the methodology. The computational methodology for landfill carbon storage and methane generation was adjusted slightly to reflect the carbon content of methane. Generation and recovery percentages were also updated based on the MSW in the United States: 2003 Facts and Figures report. These updates resulted in relatively minor changes to the majority of emission factors utilized in WARM.
WAste Reduction Model (Warm) Version 6.1 (1,987 KB xls)
This version was released in December 2004 and included a couple of minor revisions to the prior WARM version 6. The emission factor for transportation of waste to landfill by combination truck was revised. In addition, revisions were made to the landfill-gas-to-energy offsets for users interested in reporting to the U.S. Department of Energy’s 1605(b) program. The landfill-gas-to-energy offsets for 1605(b) users were revised to be phased in over 30 years, rather than the total offset being applied in year one.
WAste Reduction Model (WARM) Version 6 (1,891.5 KB xls)
This version was released in March 2004 and incorporated several updates/improvements. Five new material types were added: personal computers, carpet, clay bricks, aggregate, and fly ash. Emission factors for all other materials were updated based on new information related to the current mix of recycled and virgin inputs; new data on municipal solid waste generation and recovery from the 2001 Facts and Figures; and the energy and greenhouse gas equivalencies were updated based on more recent statistics from the U.S. Department of Energy (DOE) Energy Information Administration (EIA). These equivalencies are intended to put results in units that may be more “tangible” than British thermal units or metric tons of carbon (e.g., number of barrels of oil, number of households’ annual energy consumption, and number of gallons of gasoline).
WAste Reduction Model (WARM) Version 5 (1,660 KB xls)
This version was released in December 2003 and included revised estimates for PFC emissions and carbon anode carbon dioxide emissions associated with aluminum production based on data reported in the Inventory of U.S. Greenhouse Gases and Sinks: 1990-2000.
WAste Reduction Model (WARM) Version 4 (1,767 KB xls)
This version was released in May 2002 and included the latest data on municipal solid waste characterization based on the 2000 Facts and Figures Report, and electricity generation data for the year 2000 from the DOE’s EIA. Additionally, this version uses life-cycle energy data sources from ORD (RTI), rather than OSW (Franklin) as used in previous versions. In general, ORD's data set of energy, fuel mix, and loss rates is likely to be more up-to-date than some of the information from OSW. The ORD data was used for those materials with a complete set of ORD energy intensity and fuel mix data. This information was not available for wood products or steel because ORD did not develop emission factors for wood products and the ORD steel data was not sufficiently disaggregated to replace the existing OSW data.
WAste Reduction Model (WARM) Version 3 (3,182 KB xls)
This version was released in November 2001 and reflected several improvements made to the previous version of WARM (version 2). For participants in the U.S. Department of Energy’s 1605(b) program, results and summaries could now be viewed by gas, phased over time, and phased over time by gas. The ability to view results by gas shows emissions for carbon dioxide, methane, nitrous oxide, tetrafluoromethane, hexafluoroethane specifically, rather than only total emission reductions in terms of metric tons of carbon or carbon dioxide equivalent. The phased results and summaries show the emissions of the waste management practices for year one, for years 2-15, for years 16-30, and for all years. Results and summaries phased by gas shows results for the five gases for year one, years 2-15, years 16-30, and for all years. New materials were also added to this version and the transportation to landfill calculations were updated using data on carbon dioxide emissions per mile of freight transport.
WARM Version 1 & Version 2 (1,026 KB xls)
The first version of WARM was released in 1998, followed by the release of version 2 in December of 1999. At this stage, WARM was undergoing rapid change and growth in terms of its capabilities. These first versions included 17 material types (metals, plastics, organics, and mixed paper and recyclables) as well as the basic options still available in WARM such as the ability to specify current mix or virgin materials, the type of landfill gas control system, and the transportation distance to the waste management options.
ReCon
ReCon
ReCon version 2
This is the latest edition of the tool available to the public. It was released in July 2005 and contains several updates and improvements. Copper wire was added as a new material type providing additional resolution to the metals category. The latest statistics on national average electricity generation fuel consumption were added along with recent research on landfill methane generation and carbon sequestration associated with organic matter; the retail transportation component of the life-cycle was added to the methodology. Disposal percentages were also updated based on the MSW in the United States: 2003 Facts and Figures report. These updates resulted in relatively minor changes to the majority of emission factors utilized in ReCon.
ReCon version 1
The first version of ReCon was released in March 2004. This first version included 16 material types (metals, glass, plastics, paper types, and wood) as well as the ability to specify the percent of recycled content in the alternative and baseline scenarios or use default recycled content values. As part of the avoided disposal calculation the national average disposal rates for combustion and landfilling were based on the MSW in the United States: 2000 Facts and Figures report.