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Model History
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Waste Management and Greenhouse Gases: A Life-Cycle Assessment of Emissions and Sinks (2nd Edition) has become somewhat outdated.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 8
This is the latest edition of the model available to the public. It was released
in August 2006 and contains several updates and improvements. The latest statistics
on national average electricity generation fuel mix were added along with recent
research on landfill methane generation and forest carbon sequestration, and tires
were added as a new material type. These updates resulted in relatively minor changes
to the majority of emission factors utilized in WARM.
WARM Version 7 (486 kb WinZip archive)
This version 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 (480 kb WinZip archive)
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 (463 kb WinZip archive)
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 (395 kb WinZip archive)
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 (422 kb WinZip archive)
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 (1,986 kb WinZip archive)
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 (690 kb WinZip archive)
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 Version 3
This is the latest edition of the tool available to the public. It was released
in August 2006 and contains several updates and improvements. The latest statistics
on national average electricity generation fuel mix were added along with recent
research on landfill methane generation and forest carbon sequestration. These
updates resulted in relatively minor changes to the majority of emission factors
utilized in ReCon.
ReCon version 2
This version 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.