Calculating Greenhouse Gas Emissions
 With the WAste Reduction Model

"TTie WAste Reduction Model (WARM)
  I  was created by the U.S. Environmen-
tal Protection Agency (EPA) to help solid
waste planners and organizations estimate
greenhouse  gas (GHG)  emission  reduc-
tions from several different waste manage-
ment practices. WARM  is available  in a
Web-based  calculator format and as a
Microsoft Excel®  spreadsheet. Both  ver-
sions  of WARM  are available on EPAs
Web site at www.epa.gov/mswclimate.

WARM calculates and totals GHG emis-
sions  of  baseline  and  alternative waste
management practices—source reduc-
tion,  recycling,  combus-
tion,  composting, and
landfilling. The model cal-
culates emissions in metric
tons of carbon  equivalent
(MTCE)1  across  a  wide
range of  material  types  that
compose municipal solid waste
(MSW).  In addition,  the
Microsoft Excel®  version can
break down  emission results by
type of GHG (carbon  dioxide,
methane,  etc.). The user can con-
struct various scenarios by simply entering
data on the amount of waste handled by
material type and by management practice.
WARM then automatically  applies emis-
sions factors specific to material type and
management practice to calculate the GHG
emissions  of each scenario.  Several key
inputs, such as landfill gas collection and
transportation distances to MSW facilities,
can be modified by the user.
The GHG emissions factors were devel-
oped  following  a life-cycle  assessment
methodology using estimation techniques
developed for  national inventories of
GHG emissions. EPAs report Greenhouse
Gas  Emissions  From  Management of
Selected Materials in Municipal Solid Waste
(EPA  530-R-98-013)   describes  this
methodology in detail. For a free copy of
this report, visit www.epa.gov/mswclimate
or call EPAs RCRA hotline at 800 424-


            WARM was  developed  for
            solid waste managers (from
       state and local governments and
        other organizations) who want
         to calculate the GHG emissions
         associated with different waste
          management options. Emis-
           sions estimates provided by
           WARM are intended to sup-
            port voluntary GHG mea-
            surement and  reporting
             initiatives. These initia-
           tives include waste manage-
 ment components of  climate change
action plans, the Department of Energy's
I605(b) voluntary program for reporting
GHG emissions, and other waste manage-
ment projects for which an understanding
of GHG emissions is desired.

Before using WARM,  you first  need to
gather data on your baseline waste manage-
ment practices and an alternative scenario.
^MTCE is a unit of measurement that expresses the heat-trapping effects of various green-
house gas emissions in carbon equivalents. An international protocol has established carbon
dioxide (CO2) as the reference gas.

You should know how many tons of waste you manage
(or would manage)  for a given time period under each
scenario by material type and by management practice.
Both models allow you to customize your results based on
project specific landfill gas recovery practices and trans-
portation distances. Note that you may use default values
if you are unsure of landfill gas recovery practices and/or
transportation distances.
Web-based Version:
        To use the web-based version of WARM,  you
will need  Internet Explorer or Netscape  versions 4 or

•   For the web-based WARM model to be able  to cal-
culate your GHG emissions you  must enter the tons of
each material  type managed into the baseline and alterna-
tive management tables. The boxes in the baseline  and
alternative tables correspond to specific material types and
management  practices. Be sure to enter your data in the
correct boxes.
     MSW Material Types
     Recognized  by WARM
     Newspaper     Glass
     Office Paper    HOPE
     Corrugated     LDPE
     Boxes          PET
     Mixed Paper*   Dimensional
     Aluminum      Lumber
Steel Cans
      * Broad. Residential, and Office
Answer the questions pertaining to landfill gas recovery
and trsnsportation distance by selecting the appropriate
toggle  buttons.  If the requested  data is not available,
WARM will use the national average defaults.

•   Once you've completed the tables and answered all
of the  questions on the inputs page, WARM has all the
information it needs to calculate the GHG  emissions
associated with the baseline  and alternative waste man-
agement scenarios you specified. Click "create summary"
to see your results.

•   The summary sheet provides a concise  report of
GHG  emissions from the baseline and alternative waste
management scenarios, as well as a net emissions figure.
                                                   Once you have seen your results, you can return to the
                                                   inputs page to run  additional scenarios by selecting the
                                                   button labeled "exit summary."
                                                   Alternatively, you can view the emission factors used to
                                                   estimate emissions for various materials and management
                                                   practices;  note  that these emission factors will reflect
                                                   national average default values for landfill gas recovery
                                                   and transportation distances. To access these emission fac-
                                                   tors, select the button labeled  "view emission factors"
                                                   from either the inputs page or the summary page.
                                                   Microsoft Excel® Version:
                                                           To use Microsoft Excel® WARM, you will need
                                                   Microsoft Excel® version 5.0 or higher.

                                                   •    Once you've gathered these data, you're ready to get
                                                   started with WARM. Follow directions on the Web site
                                                   for downloading and installing the Microsoft Excel® ver-
                                                   sion of WARM. After successfully downloading the file,
                                                   open the  spreadsheet. WARM will  prompt  you with
                                                   "Open as  read-only?" If you plan to  save your work in
                                                   WARM,  click "No." Otherwise, click  "Yes." Next,
                                                   WARM will prompt you with "This document contains
                                                   links. Re-establish links?" Simply click "No."
                                                     WARM Summary Report

•   Now, click on the "Analysis Inputs" tab at the bottom
center of the screen  to open  the  input  sheet. Follow  the
instructions for Steps  1 and 2 to fill in the tables describing
your baseline and proposed alternative waste management sce-

    Fill in the data requested  in Steps 3—6. In these steps,
WARM is asking for additional waste handling information to
allow it to customize  its calculations to your waste manage-
ment situation. For example, you are asked for data on trans-
portation distances and on your landfill gas and ferrous metal
recovery systems, if applicable. If the  requested data is not
available, WARM will use the national average defaults.

    Once  you've  completed  Steps 1—6  on  the "Analysis
Inputs" sheet, WARM has the information it needs to calcu-
late the GHG emissions attributable to  the baseline and alter-
native waste management scenarios you've specified. Emissions
calculations are presented on three separate output sheets, as
described below. From the "Analysis Inputs" sheet, click on a
tab at the bottom of the screen for the results sheet you want
to view first.
 — The "Analysis Results" sheet shows GHG emissions for each
scenario in units of MTCE. You can compare the total impact
of the baseline and alternative scenarios, or, if you want more
detail, you can scroll down to view GHG emissions per mate-
rial type and management practice.

 — The "Analysis Results by Gas" sheet provides a breakout of
emissions of specific GHGs per material type under each sce-
nario. The specific GHGs  are carbon dioxide (CO 2), methane
(CH^), nitrous oxide (N2O), and perfluorocarbons (CF^ and
 — The "Summary Report" sheet provides a concise report of
GHG emissions from the baseline and alternative  waste
management scenarios, as well as a net total MTCE figure.

If you need additional asistance with using WARM,  please
email Henry Ferland at ferland.henry@epa.gov or Eugene Lee
at lee.eugene@epa.gov.