EPA Optimization Model for Reducing
Emissions of Greenhouse Gases from
Automobiles (OMEGA)
Core Model Version L4.56
&EPA
United States
Environmental Protection
Agency
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EPA Optimization Model for Reducing
Emissions of Greenhouse Gases from
Automobiles (OMEGA)
Core Model Version L4.56
Assessment and Standards Division
Office of Transportation and Air Quality
U.S. Environmental Protection Agency
&EPA
United States
Environmental Protection
Agency
EPA-420-B-16-064
July 2016
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Table of Contents
I Background 3
II Model Overview 3
III Input Files 7
A The Market File: Vehicle Fleet Characterization 7
B The Technology File: Technology Package Characterization 12
C The Fuels File: Physical Properties and Prices of Fuel and Energy Sources 14
D The Scenario File: Definition of Regulatory Scenarios and Other Economic Parameters 16
Universal Target 17
Piece-wise Linear 17
Logistic Curve Target 19
E The Reference File: Vehicle Survival Rates and Miles Driven 22
F Non-editable Input Data 23
G Input Files Currently Distributed with Model 23
IV Model Operation 24
A Calculating Technology Effective Basis (TEBs) and Cost Effective Basis (CEBs) 24
B Calculating Other Effectiveness Basis (OEBs) 25
C Platform Aggregation 25
D Technology Application 26
D.i Determination of Manufacturer-Specific CO2 Emission Standards 27
D.ii Converting Lifetime Refrigerant Emissions to CO2-Equivalent emissions per Mile 27
D.iii Application of Technology - Methodology 29
D.iv Technology Application Ranking Factors 34
D.v Applying Technology - Calculations 40
V Output Files 42
A Summary of Outputs 42
A.i Log of Technology Application Steps - Text Format 43
A.ii Summary of Cost and Emissions -Excel Format 46
A.iii Summary of Technology Pack Distribution - Text format 46
A.iv VH1 /Final summary of Vehicle Attributes-Excel Format 47
A.v VH2 / Stepwise listing of Vehicle AttributesExcel Format 47
VI Running the Model 47
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I Background
On-road vehicles are the predominant source of greenhouse gas (GHG) emissions from
the transportation sector. Of all on-road vehicles, light-duty vehicles and light-duty trucks
(hereafter referred to as cars and trucks) produce the majority of the GHG emissions. There are
many methods for reducing GHG emissions from cars and trucks due to the myriad technology
options available to improve the efficiency of vehicles. A detailed analysis of the costs and
benefits of various GHG emissions reduction requires an application that accounts for all the
potential technologies. Therefore, EPA's Office of Transportation and Air Quality (OTAQ) has
developed the Optimization Model for reducing Emissions of Greenhouse gases from
Automobiles (hereafter referred to as the "OMEGA" model) to help facilitate the analysis of the
costs and benefits of reducing GHG emissions from cars and trucks.
This documentation accompanies the sixth public release of the OMEGA model.
Versions 1.0.0 and 1.0.2 were respectively released with the noticed of proposed rulemaking and
final rule regarding "Model Year 2012-2016 Light-Duty Vehicle Greenhouse Gas Emissions
Standards and Corporate Average Fuel Economy Standards." Versions 1.3.0, 1.4.0, and this
version were respectively released with the first notice of intent, the proposed rulemaking, and
the final rule regarding the "2017 and Later Model Year Light-Duty Vehicle Greenhouse Gas
Emissions and CAFE Standards." These model releases, as well as their related inputs and
documentation are available at the OMEGA page on the EPA website.l
The model is written in the C# programming language. Inputs to and outputs from the
model are provided using spreadsheet and text files. The spreadsheet output files also facilitate
additional manipulation of the results. The model source code is available in the relevant
rulemaking dockets.2
EPA has established a webpage for the OMEGA model on the EPA agency website
(http://www.epa.gov/otaq/climate/models.htm). The OMEGA version 1.4.56 release includes a
set of sample input files; those used to support EPA's 2016 Draft Technical Assessment Report
(Draft TAR) on cars and light trucks for model years 2021+ are also available on the website.
Input files from earlier versions of OMEGA are not compatible with this release. Periodic
updates of both the model and this documentation will be available to be downloaded. Those
interested in using the model are encouraged to periodically check this website for these updates.
II Model Overview
Broadly speaking, the OMEGA model evaluates the relative cost and effectiveness of
available technologies and applies them to a defined vehicle fleet in order to meet a specified
GHG emission target. Once the target has been met, OMEGA reports out the cost and societal
benefits of doing so. This document focuses on the core model, which is the component which
calculates cost of compliance. OMEGA models two GHGs; carbon dioxide (CO2) from fuel use
and refrigerant emissions from the air conditioning (A/C) system.
OMEGA is primarily an accounting model. It is not a vehicle simulation model, where basic
information about a vehicle, such as its mass, aerodynamic drag, an engine map, etc. are used to
1 https://www3 .epa.gov/otaq/climate/models.htm
2 EPA-HQ-OAR-2004-0075 and EPA-HQ-OAR-2010-0799
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predict fuel consumption or CO2 emissions over a defined driving cycle.3 Such simulations may
be used to inform the OMEGA inputs, but are not performed by OMEGA itself.
While OMEGA incorporates functions which generally minimize the cost of meeting a
specified CO2 target, it is not an economic simulation model which adjusts vehicle sales in
response to the cost of the technology added to each vehicle. While OMEGA allows vehicle
sales to change over time, the vehicle sales in OMEGA 1.4.56 do not dynamically respond to the
addition of technology.4
OMEGA can be used to model either a single vehicle model or any number of vehicle
models. Vehicles can be those of specific manufacturers or generic fleet-average vehicles.
Because OMEGA is an accounting model, the vehicles can be described using only a relatively
few number of terms. The most important of these terms are the vehicle's baseline emission
level, the level of CO2 reducing technology already present, and the vehicle's "type," which
indicates the technology available for addition to that vehicle. Information determining the
applicable CO2 emission target for the vehicle must also be provided. This may simply be
vehicle class (car or truck) or it may also include other vehicle attributes, such as footprint.5
Since there are a large number of technologies which reduce CO2 emissions and a wide
array of different vehicle systems to which they apply, the manufacturers' design and production
processes play a major role in determining the technology cost associated with lowering fleet-
wide CO2 emissions. Vehicle manufacturers typically develop several unique models based on a
limited number of shared vehicle platforms, allowing for efficient use of design and
manufacturing resources. The platform typically consists of common vehicle architecture and
structural components. Given the very large investment put into designing and producing each
vehicle model, manufacturers typically plan on a major redesign for the models approximately
every 5 years. At the redesign stage, the manufacturer will upgrade or add all of the technology
and make all of the other changes needed in order that the vehicle model will meet the
manufacturer's plans for the next several years. This includes meeting all of the emissions and
other requirements that would apply during the years before the next major redesign of the
vehicle.
This redesign often involves a package of changes, designed to work together to meet the
various requirements and plans for the model for several model years after the redesign. This
often involves significant engineering, development, manufacturing, and marketing resources to
create a new product with multiple new features. In order to leverage this significant upfront
investment, manufacturers plan vehicle redesigns with several model years' of production in
mind. Vehicle models are not completely static between redesigns as limited changes are often
incorporated for each model year. This interim process is called a refresh of the vehicle and
generally does not allow for major technology changes although more minor ones can be done
(e.g., aerodynamic improvements, valve timing improvements). More major technology
upgrades that affect multiple systems of the vehicle thus occur at the vehicle redesign stage and
not in the time period between redesigns.
3 EPA has released other models that perform full vehicle simulations. See the ALPHA
(http://www.epa.gov/otaq/climate/alpha.htm') and GEM models (http://www.epa.gov/oms/climate/gem.htmX
4 OMEGA may be expanded in the future to incorporate such market responses, however, such responses may
currently be addressed "outside of the model" through sequential model runs with market adjustments made between
runs.
5 A vehicle's footprint is the product of its track width and wheelbase, usually specified in terms of square feet.
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There are a wide variety of emissions control technologies which involve several
different vehicle systems. Many can involve major changes to the vehicle, such as changes to
the engine block and heads, or redesign of the transmission and its packaging in the vehicle.
This calls for tying the incorporation of the emissions control technology into the periodic
redesign process. This approach reflects manufacturer capability to develop appropriate
packages of technology upgrades that combine technologies in ways that work together and fit
with the overall goals of the redesign. It also reflects the reality that manufacturers fit the
process of upgrading emissions control technology into its multi-year planning process, and it
avoids the large increase in resources and costs that would occur if technology had to be added
outside of the redesign process.
Within OMEGA, GHG emission control technology can be applied individually or in
groups, often called technology "packages." The user specifies the cost and effectiveness of
each technology or package for a specific "vehicle type," such as midsize cars with V6 engines
or minivans. The user can limit the application of a specific technology to a specified percentage
of each vehicle's sales (i.e., a "cap"). The effectiveness, cost, application limits of each
technology package can also vary over time.6 A list of technologies or packages is provided for
each vehicle type, providing the connection to the specific vehicles being modeled.
OMEGA is designed to apply technology in a manner similar to the way that a vehicle
manufacturer might make such decisions. In general, the model considers three factors which
EPA believes are important to the manufacturer: 1) the cost of the technology at the consumer
level, 2) the value which the consumer is likely to place on improved fuel economy and 3) the
degree to which the technology moves the manufacturer towards its CO2 emission target.
Technology can be added to individual vehicles using one of three distinct ranking
approaches. Within a vehicle type, the order of technology packages is set by the user. The
model then applies technology to the vehicle with the lowest Technology Application Ranking
Factor (hereafter referred to as the TARF). OMEGA offers several different options for
calculating TARF values. One TARF equation considers only the cost of the technology and the
value of any reduced fuel consumption considered by the vehicle purchaser. The other two
TARF equations consider these two factors in addition to the total GHG emissions reduced over
the life of the vehicle. Fuel prices by calendar year, vehicle survival rates and annual vehicle
miles travelled (VMT) with age are provided by the user to facilitate these calculations.
For each manufacturer, OMEGA applies technology to vehicles until the sales-weighted
GHG emission average complies with the specified GHG emission standard or until all the
available technologies have been applied. The GHG emission standard can be a flat standard
applicable to all vehicles within a vehicle class (e.g., cars, trucks or both cars and trucks).
Alternatively the GHG standard can also be in the form of a linear or constrained logistic
function, which sets each vehicle's target as a function of vehicle footprint (vehicle track width
times wheelbase). When the linear form of footprint-based standard is used, the "line" can be
converted to a flat standard for footprints either above or below specified levels. This is referred
to as a piece-wise linear standard.
6 "Learning" is the process whereby the cost of manufacturing a certain item tends to decrease with increased
production volumes or over time due to experience. While OMEGA does not explicitly incorporate "learning" into
the technology cost estimation procedure, the user can currently simulate learning by inputting lower technology
costs in each subsequent redesign cycle based on anticipated production volumes or simply with time.
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The GHG emission target can vary over time, but not on an individual model year basis.
One of the fundamental features of the OMEGA model is that it applies technology to a
manufacturer's fleet over a specified vehicle redesign cycle. OMEGA assumes that a
manufacturer has the capability to redesign any or all of its vehicles within this redesign cycle.
OMEGA does not attempt to determine exactly which vehicles will be redesigned by each
manufacturer in any given model year. Instead, it focuses on a GHG emission goal several
model years in the future, reflecting the manufacturers' capability to plan several model years in
advance when determining the technical designs of their vehicles. Any need to further restrict
the application of technology can be effected through the caps on the application of technology
to each vehicle type mentioned above.
GHG emission standards are specified in terms of CO2 equivalent emissions. These CO2
equivalent emissions can be based on any test procedure. The only requirement is that the base
CO2 emissions specified for each vehicle and the effectiveness of the specified technologies be
based on the same test cycle(s). For example, these emissions can simply be those from the
tailpipe as measured over the current two-cycle GHG standard test procedure or they can also
include tailpipe CO2 emissions from air conditioner use, as well as refrigerant emissions from the
air conditioning system. In the case of the latter, the descriptions of vehicle emissions and
technologies must include baseline refrigerant emissions and the effectiveness of each
technology in reducing these emissions. GHG emissions could also be based on the 5-cycle
formulae now used to calculate most vehicles' fuel economy labels. The user simply needs to
take care to specify CO2 and refrigerant emission and technology effectiveness estimates which
are based on emissions over all five emission tests and as combined according to the five-cycle
formulae. OMEGA bases all of its calculations on a single estimate of test cycle emissions.
Compliance cannot be specified for two distinct test cycles, for example, city and highway test
emissions. Only combined city alone, highway alone or city-highway emissions can be modeled.
Once technology has been added so that every manufacturer meets the specified targets
(or exhausts all of the available technologies), the model produces a variety of output files.
Outputs include specific information about the technology added to each vehicle and the
resulting costs and emissions. Average costs and emissions per vehicle by manufacturer and
industry-wide are also determined for each vehicle class.
The remainder of this document is divided into four sections. The first section describes
the information which can be input to the model. The second section describes the application of
technology in order to comply with the specified standards, what we define as the "core model."
The third section describes the various output files produced by the model. The fourth section
describes the steps necessary to operate the OMEGA model.
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Ill Input Files
OMEGA is designed to be flexible in a number of ways. Very few numeric values are
hard-coded in the model, and consequently, the model relies heavily on its input files. The
model utilizes five input files: Market, Technology, Fuels, Scenario, and Reference. All of the
input files are Microsoft Excel 2003 spreadsheets and should not be converted into other formats.
The headings of the various types of input data are contained in Row 1 of each worksheet. It
should be noted that these headings cannot be modified by the user. Each input file also contains
two common types of worksheets. One is named "Validation List" and lists the types of value
allowed in each column along with an allowed range of valid values. This worksheet is typically
hidden and can be viewed using the Format/Sheet/Unhide command. The user can change the
range of valid values as desired. The user should not change the type of data shown as OMEGA
is designed to look for certain types of information in each column and changing the values
entered in an input file does not affect this expectation.
The second common worksheet is named "Errors." This worksheet contains a button
labeled "Validate Data" which can be selected. When "clicked" this button triggers a macro
which determines if all values in the current workbook fit the expected type of data and fall
within the allowed range of values. Cells that do not fit the criteria are listed and the problem
described. This function can be very useful when developing new input files by reducing the
number of aborted model runs. While useful, please note that the error validation routines are
intended to be used only as a troubleshooting guide and may falsely indicate errors or may not
indicate all errors.7
It is important to note that OMEGA expects all the cells below the last row of required
data to be blank and, more specifically, to have never been written into. If these cells are used
for temporary calculations, the user should go further below to a row which has never been
written into and copy the entire row of blank cells into the row which have been used
temporarily. The error identification process will then recognize these cells as actually being
blank.
A The Market File: Vehicle Fleet Characterization
The market input file contains much of the required information which describes the vehicles
being modeled. This file consists of three worksheets in addition to the Validation List and
Errors worksheets: Vehicle, Manufacturer, and Vehicle Type. The "Manufacturer" and "Vehicle
Type" worksheets are lists of valid values for columns C and E in the Vehicle worksheet. The
"Vehicle" worksheet, which is the substance of the market file, is discussed below. New to this
public release of OMEGA is the "Fleet Protection" sheet used to estimate fatality impacts
associated with the given model run. This new sheet is discussed below.
7 Generally, OMEGA is moving towards a dynamic where more error reporting is provided by the model itself,
rather than these validation routines. The trace log, located in the same file directory as the model executable,
provides useful diagnostics on the model run.
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Table 1 shows the various types of data included in the "Vehicle" worksheet.
Table 1 Input Data in Vehicle Worksheet of the Market File*
Column
A
B
C
D
E
F
G
H
1
J
K
L
M-T
U
V
W
X
Y
Name
Platform Index #
Vehicle Index #
Manufacturer
Model
Vehicle Type #
Fleet Type
Classic Fleet Type
Vehicle Safety Class
CVCM Class
EPA Vehicle Class
Baseline Price
Baseline Sales
Annual Sales by Cycle
Combined FE (mpg)
Tailpipe CCh (g/mi)
Footprint (ft2)
Curb Weight (Ib)
No. of Cylinders
Column
Z
AA
AB
AC
AD
AE
AF
AG
AH
Al
AJ
AK-CH
CI-EF
EG-GD
GE-IC
Name
Displacement (L)
Horsepower
Max Seating
Transmission Type
Drive
Structure
Towing Capacity
Primary Fuel Type
Combined EC (kWh/mi)
Refrigerant Type
Refrigerant Lifetime Leakage (g)
TEBTech Package 1-50
CEBTech Package 1-50
OEBTech Package 1-50
Tech Tracking Codes Package 1-
50
* Columns highlighted in gray are not currently used by OMEGA
Column A contains a positive numerical identifier matching each vehicle with a specific
platform type. Each platform represents a unique combination of vehicle characteristics as
desired by the user. During input data pre-processing OMEGA automatically creates a version
of the market.xls data set aggregated by manufacturer and unique platform. This process is
described further in later sections.
Column B contains a unique, positive numerical identifier for each vehicle being
modeled. The indices do not need to be in numerical order, just unique and positive. Column C
contains the name of each manufacturer. There are no requirements with respect to the names,
except that the user needs to take care that vehicles intended to be produced by the same
manufacturer are given exactly the same name. Slight differences in spelling or spacing will
cause the model to treat them as separate manufacturers. A list of manufacturers has been
provided in the validation routine to help avoid this issue. Column D contains an alpha-numeric
name for each vehicle. These names do not need to be unique, simply to be as descriptive as the
user desires.
Column E contains the vehicle type number. This value provides the connection
between the vehicles listed in the market data worksheet and the available technologies listed in
the Technology file.
Column F contains the vehicle class designator. Currently OMEGA can model up to two
vehicle classes: cars indicated with "C" and trucks indicated with "T." This code provides the
connection between the vehicles listed in the market data worksheet and the standards listed in
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the Scenario file. If only one standard applicable to both cars and trucks is being modeled,
vehicles can be labeled as either cars or trucks or both. If both vehicle labels are used,
compliance will still be based on the combination of both vehicle classes, but emissions will be
tracked separately in the model's outputs. This latter situation is advantageous if cars and trucks
are to have distinct scrappage rates and annual travel estimates.
Column G contains the car/truck classification of vehicles under the pre-MY 2011 CAFE
definition. This column is not currently used by the OMEGA model.
Column H contains the vehicle safety class. These data are used in conjunction with the
data on the "Fleet Protection" sheet to estimate fatality impacts of the given model run.
Column I contains the Consumer Vehicle Choice Model (CVCM) class. This column is
not currently used by the OMEGA model.
Column J contains the EPA Class, in terms of Compact car vs. Midsize car vs. Large
SUV, etc. This column is not used by OMEGA.
Column K contains the Baseline Price. This column, meant for use in conjunction with
the Consumer Choice Model, is not currently used by OMEGA.
Column L contains baseline sales. The baseline is the model year prior to the first year
of the first redesign cycle being modeled. Baseline sales are not used in the core model to add
technology to facilitate compliance; instead they are used in order to linearly interpolate annual
vehicle sales during the interim years between the baseline year and the year of the end of the
first redesign cycle. Sales must be positive and may be fractional.
Columns M through T contain sales for the last year of each of up to eight redesign
cycles. Sales must be positive and may be fractional. The basic assumption made by the model
related to the length of the redesign cycle is quite simple: that every vehicle sold by the
manufacturer is capable of being redesigned within a redesign.
Sales must be entered for each vehicle, even if the value of sales is zero. Values need
only be entered for redesign cycles actually being modeled. Thus, if only one redesign cycle is
being modeled, then sales need only be entered in Column M. Columns N through T can be
blank in this case. Sales can change in any manner between redesign cycles.
Column U contains each vehicle's baseline fuel economy value in miles per gallon
(mpg). It is not currently used by the model.
Column V contains each vehicle's baseline CO2 emissions in grams per mile (g/mi) over
whichever test cycle or cycles comprise the basis for compliance with the standards described in
the Scenario file. This value should not include the CO2 equivalent emissions related to
refrigerant leakage emissions. Those emissions are described in later columns. The CO2
emissions of Column V could include the CO2 equivalent emissions of GHGs like methane and
nitrous oxide, as long as the effectiveness of the technologies described in the Technology file
and the standards listed in the Scenario file consider these emissions in a consistent manner.
Column W contains each vehicle's footprint value in square feet. This value is used to
determine each vehicle's CO2 emission target when the standard is either a constrained logistic
curve or linear function.
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Columns X through AE describe several vehicle attributes which are not currently used
by the model. These are included to facilitate future versions of the model which may base
compliance or evaluate model output using one or more of these attributes. Column AF contains
the vehicle towing capacity in pounds.
Column AG contains a designator for each vehicle's primary fuel type. Any fuel type is
allowed in the model, so long as its details appear in the Fuels input file. Plug in hybrid vehicles
would be designated by their liquid fuel type, depending on which liquid fuel they used. The
model will consider the electricity used by plug in vehicles based on the value of electricity
consumption per mile described in Column AH, which is described below. Electric vehicles
must be designated with the fuel "EL." Fuel names are case sensitive, and each vehicle fuel
must appear, in exactly the same format, in the fuels file.
Column AH contains the vehicle's baseline electricity consumption in units of kilowatt-
hour per mile (kw-hr/mi). This value is used in calculating the fuel savings component of the
TARF equation, in which a comparison must be made between vehicles and technologies which
may consume different types of energy sources, such as liquid gasoline or diesel, or electricity.
Since consumers tend to make decisions on which vehicle to purchase based on how much the
vehicle costs them to drive it, this column helps the model account for any energy in the baseline
vehicles which is supplied by the electrical grid. This term only applies to plug in hybrids and
battery based electric vehicles. In the Fuels input file, OMEGA allows the user to input a value
for the GHG emissions associated with generating a kw-hr of electricity when determining
compliance with the GHG standards. Should a non-zero value be entered, the level of electricity
usage per mile also affects the vehicle's baseline CO2 emission level when the model is run.
Column AI designates the type of refrigerant used by the vehicle. This designator must
match one of the types of refrigerant listed on the Refrigerant worksheet of the Reference file
described further below. The primary purpose of this designation is to specify the Global
Warming Potential (GWP) of the refrigerant so that mass emissions of refrigerant leakage can be
converted to their CO2 equivalent emissions. Editable refrigerant data is in the Reference file, so
that the user can edit or add additional refrigerant names and GWPs.
Column AJ of the market file designates the lifetime leakage of the refrigerant, which the
model uses to calculate the leakage rate in CO2 equivalents. EPA chose to input the lifetime
leakage instead of the leakage rate because the lifetime leakage is easier to quantify. The yearly
distribution of leakage is hard-coded, and OMEGA uses it to convert the refrigerant leakage to
grams of CO2 equivalents per mile.
Columns AK through CH are used to track technology that may be present in the baseline
or reference case. This data is necessary to prevent the model from double counting technology
costs and GHG improvements. Columns AK through CH represent the CO2 emissions in g/mi
for the given vehicle if equipped with the package specified (package 1 through 50). These CO2
values carefully account for the technology already in the baseline vehicle so as to avoid any
double counting of CO2 reduction made possible by the technologies in the given package.
Similarly, columns CI through EF represent the cost increase when applying the specified
package (package 1 through 50) to the baseline vehicle. Again, these cost values carefully
account for the technology already in the baseline vehicle so as to avoid any double counting of
technology costs.
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Columns EG through GD contain Other Effectiveness Basis (OEB) gram-per-mile credits
that may be associated with each technology package. Typically these are negative numbers.
While each technology package may have an associated gram-per-mile credit (specified in the
Technology.xls input data set) those are only applied when calculating the TARF CO2 value.
When calculating total vehicle CO2 for compliance purposes, the OEB values from columns EG-
GD are used instead. As documented in a later section, the use of OEBs provides vehicle level
accounting for credits.
Columns GE through 1C contain technology codes denoting the technologies contained in
each package 1 through 50. These codes are used by the OMEGA core model in generating the
Technology Tracking output file. This is a new feature in OMEGA and a new output file. This
output file makes it much easier to determine the final technology penetrations of any given
OMEGA run.
Also new is the "Fleet Protection" worksheet of the Market file which contains the data
shown in Table 2.
Table 2 Input Data in Fleet Protection Worksheet of the Market File
Column(s)
A
B
C
D
E
F
G
H
Contents
Vehicle Safety Class Number
Vehicle Safety Class
Regression Mass Breakpoint
Regression Mass Breakpoint Direction
Safety Class Description
Change per 100 Ibs
Base per billion miles
FMVSS Adjustment
Column A contains an index for the other entries in the worksheet.
Column B contains the vehicle safety class as PC, LT or CM. These correspond to
passenger car, light-truck and cross-over utility/minivan and should use identical values to those
in Column H of the Vehicle worksheet.
Column C contains the regression mass breakpoint for each vehicle safety class specified
in Column B.
Column D contains either LE (less than or equal to) and GT (greater than) and are
measures relative to the entries in Column C.
Column E contains a description of the safety class.
Column F contains the change in fatalities for every 100 pounds removed from a vehicle
within the given safety class.
Column G contains the base per billion miles entry, or the number of fatalities per billion
miles traveled by a vehicle(s) in the given safety class.
Column H contains a federal motor vehicle safety study adjustment value.
Values in columns C, F, G and H come directly from the safety analysis chosen to
support the given OMEGA analysis.
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To make the safety-related calculations, OMEGA looks to the Tech Tracking codes
contained in Columns GE-IC of the Vehicle worksheet of the Market file. Specifically, OMEGA
uses the WRnet value since that value represents the net reduction in weight relative to the curb
weight specified in Column X of the Vehicle Worksheet for the given vehicle. OMEGA tracks
pounds removed from each vehicle and calculates safety-related results based on the number of
pounds removed within each of the wieght ranges specified in Column C of the Fleet Protection
worksheet. OMEGA determines the safety impacts per billion miles per vehicle then multiplies
that result by the sales value shown in the appropriate column of the Vehicle worksheet to
determine the end result for each given vehicle. Results are then summed by scenario for cars
and trucks and provided in the "SummaryOutputResults" file discussed in Section V.
B The Technology File: Technology Package Characterization
The technology input file defines the technology packages (up to 50 per vehicle type)
which the model can add to the vehicle fleet. For each vehicle type, the user must add a separate
row for each technology package in the order of how OMEGA should add them to that specific
vehicle type. This approach puts considerable onus on the user to develop a reasonable sequence
of technologies. However, the model also produces output information which can help the user
determine if a particular technology package might be "out of order." The package approach
also simplifies OMEGA's calculations and enables synergistic effects among technology
packages to be included to the fullest degree possible.
There are four worksheets which contain technology packages, each worksheet keyed to
a particular redesign cycle. Another worksheet is the TechList worksheet, discussed more below.
Similar to the Market file, the Technology file contains an additional worksheet entitled "errors",
which is used for validation purposes. Table 3, below describes the data in the each redesign
cycle worksheet.
Table 3 - Input Data in Each Worksheet of the Technology File
Column(s)
A
B
C
D
E
F
G
H
1
J
K
L
M
Contents
Vehicle type number
Technology package number
Technology package name
Abbreviation
Market penetration caps
Incremental tailpipe CCh emission control effectiveness
Incremental Cost
Primary fuel of the new technology package
The prior technology package to which the given package applies
Electrical Conversion %
Gram/mile CCh credit
Refrigerant emission control effectiveness
Refrigerant type (NC = no change from previous step)
The data in this file can be categorized in four ways: 1) Information which describes the
individual packages, such as name and vehicle type; 2) Parameters the model uses to calculate
CO2 improvement, such as effectiveness and market penetration cap (the latter being the cap of
sales for each vehicle model of a vehicle type that can receive a technology package); 3)
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technology costs 4) Properties of the technology package, such as refrigerant type, fuel type,
electricity usage, credit value, and applicable fuel.
Each worksheet in the Technology input file contains a user-defined list of technology
packages for all of the different vehicle types. This list is organized in ascending order by the
vehicle type to which it applied (Column A), and then by ascending technology package
(Column B). The user need not use the full 50 lines for each vehicle type, but can stop after the
last technology package has been listed. There cannot be any blank lines between technology
packages or vehicle types. The user must record the technology packages within each vehicle
type from top to bottom in the order of how the model should add them to the particular vehicle.
In typical OMEGA usage, each package is replaced by the subsequent technology package, so it
is critical that packages improve in aggregate CO2 reduction. The user records a description of
the technology package in Column C, and abbreviation transmission code, if desired, in Column
D.
Column E contains the maximum market penetration caps for the technology packages.
When technology is sufficiently new, or the lead-time available prior to the end of the redesign
cycle is such that it is not reasonable to project that it could be applied to all vehicle models that
are of the same specific vehicle type (i.e,; all minivans), the user can limit its application to
minivans through the use of a market cap of less than 100%. If subsequent technology packages
can be applied to the vehicle, the user should consider whether in reality the new technology
would likely be applied to those vehicles which received the previous technology or those which
did not, and design the technology file accordingly. The effectiveness of adding the subsequent
technology will depend on which vehicles are receiving it.
Column F contains the Average Incremental Effectiveness (AIE) of the technology
package over the previous package (or over the baseline in the case of technology package 1).
For example, a value of 7.0% in the AIE column would denote a 7.0% tailpipe CO2 improvement
beyond any CO2 improvements already realized. ("Tailpipe CCh" refers to the CO2 emitted over
the test cycle assumed to be used to determine compliance- which relates it to vehicle
efficiency.) This value of 7% would include any synergistic effects that components of the
technology package may have with technologies that are remaining on the vehicle type.
Column G contains the incremental technology package cost, which represents the cost
beyond the cost of other technology packages that the model may have added in a previous step.
In the specific case of technology package 1 on each vehicle type, this will be the package cost
over the baseline, since no other technology has been added prior to technology package 1.
Column H and I respectively contain the fuel used by the vehicle after addition of the
technology package, and the technology package to which the given package should be applied.
The fuel abbreviations must also appear in the Fuels input file, and are case specific.
Column J contains the electrical conversion percentage. Each technology package
potentially has an "electricity conversion percentage," which refers to the increase in the grid-
supplied electrical energy consumed by the electric drivetrain relative to reduction in the
consumption of energy from liquid fuel. More specifically, the electricity conversion percentage
is the ratio of the increase in grid-supplied electrical energy used by the vehicle (in BTU per
mile) divided by the reduction in liquid fuel use (also in BTU per mile), multiplied by 100%.
Electricity is a highly refined form of energy which can be used quite efficiently to create kinetic
energy. Thus, electric motors are much more efficient than liquid fuel engines. Consequently,
13
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the electric consumption percentages input in the Technology File for plug-in hybrid vehicles
and battery electric vehicles are generally well below 100%. It may be possible that this
percentage could exceed 100% under certain circumstances, for example when one type of plug-
in vehicle is being converted into another plug-in vehicle and electricity consumption per mile is
increasing due to larger and heavier batteries, etc.
Column K contains a gram per mile credit that is applied to this technology step when
calculating the TARF CO2 values. As described above, the OEB, rather than this credit value, is
used in calculating the compliance CO2 for a vehicle using this technology package. However,
this value is used in computing the TARF.
Column L contains the refrigerant effectiveness and is based on the fraction reduction in
direct refrigerant leakage emissions and is separate from tailpipe CO2. Based on a change in
refrigerant included as part of a technology package, the model will convert the refrigerant
emissions to grams per mile of CO2 equivalent emissions, and add the resultant to the tailpipe
CO2 emissions for the vehicle compliance calculation. A value of "NC" in column M denotes
that there is "No Change" in refrigerant from the previous step, or in the case of technology
package 1, no change from the baseline refrigerant.
The TechList worksheet of the Technology input file which contains the data shown in
Table 4.
Table 4 Input Data in TechList Worksheet of the Technology File
Column(s)
A
B
Contents
Category
Tech
Column A contains the technology category into which the technology code shown in
Column B will be mapped when generating the new Technology Tracking output file.
Column B contains the technology codes and must be entered exactly as they are entered
in Columns GE through 1C of the Market file's Vehicle worksheet.
C The Fuels File: Physical Properties and Prices of Fuel and Energy Sources
The Fuels input file contains data relevant to liquid fuel and electricity, including energy,
mass, and carbon density, and annual price forecasts for up to 20 years. Similar to the other
input files, the fuels input file is comprised of two worksheets: A worksheet containing data used
by the model and an additional worksheet designed to ensure that the data is within allowable
ranges. There is a third hidden worksheet which contains the range of allowable values. Table 5
describes the layout and content of the "fuel" worksheet in the fuels input file.
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Table 5 - Input Data in Fuel Worksheet of the Fuels File
Column(s)
A
B
C*
D
E
F-Y
Contents
Fuel Type
Energy Density
Mass Density*
Carbon Density
CAFE Equivalency Factor
Fuel Price ($/gal)
*The columns highlighted in gray are not used
by the model's calculations.
Column A describes the fuel type. This value can be any descriptor desired, but EPA
typically specifies gasoline as "G", diesel fuel as "D," etcetera. The one exception is that
electricity must be designated as "EL", in order for the model to connect inputs like the
electricity conversion factor with this fuel. Please note that the fuel names in this file must
match the fuels in the technology and market files at a case specific level.
Column B contains the energy density of the energy source. For the liquid fuels, this
factor has the units of BTU per gallon. Electricity has the units of BTU per kilowatt-hour, which
is essentially a fixed conversion factor. This factor is used when a technology package increases
the ability of the vehicle to operate on grid-supplied electricity. It is used in conjunction with the
electrical conversion factors listed in the technology file.
Column C contains the mass density of the liquid fuels in terms of grams per gallon, and
is not used in the model.
Column D describes the carbon density of the energy source, and is used in the
calculation of the fuel savings component of the TARF8 as well as in the compliance
calculations. Carbon density is specified in units of grams of carbon per gram per the unit of fuel
which is associated with the fuel price. For liquid fuels, this is grams of carbon per gallon and
for electricity this is grams of carbon per kWh. If a user wishes to incorporate the upstream
emissions of the carbon content of CO2 emissions in the TARF and compliance calculations,
they could enter a positive value in this cell. Please note that these emission values are in terms
of grams of carbon, not grams carbon dioxide.
Column E contains the CAFE equivalency factor used in the calculation of manufacturer
fines. If there is a fine, and if the manufacturer fails to meet the target, then the TARF rankings
would change. However, because the OMEGA model does not allows the manufacturer to
choose to pay fines, this input should typically be set to I.9
Columns F through Y contain the fuel price either in US Dollars per gallon or US Dollars
per kWh for liquid fuel and electricity, respectively, for 20 calendar years. Fuel prices are to be
input in ascending order by year and are used when calculating the fuel savings over the payback
period in the TARF. The first calendar year listed should be that of the model year.
8 TARF formulas are discussed on page 26.
9 In other words, the OMEGA model's technology application algorithm only ceases to apply technology when a
manufacturer comes into compliance, or when all technology options have been exhausted. There is no option to
pay fines rather than comply through technology.
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D The Scenario File: Definition of Regulatory Scenarios and Other Economic Parameters
The Scenario input file contains data specifying the number and types of model runs.
The Scenarios worksheet acts as a directory for different model runs, where the user can create
an entry for any number of runs that the model can perform in succession. In the Scenarios
worksheet, the user must specify the base year, type of compliance target (CO2 or MPG), type of
compliance function, the number of redesign cycles, and the names of the other input files that
describe the vehicle fleet, technology packages, and fuel properties. At present, the model is
limited to a CO2 equivalent standard. The elements in the "Scenarios" worksheet described
above are summarized in Table 6.
Table 6 - Input Data in Scenarios Worksheet of the Scenario File
Column(s)
A
B
C
D
E
F
G
H
1
J
K
L
M
N
O
Contents
Scenario ID number
Scenario name
Baseline year
Target Type
TARF Option
GHG Target Function Type
Fleet type (single or combined)
Number of redesign cycles
Consumer Choice Model Iterations
Fleet trading limit
Market input file indicator
Technology input file indicator
Fuels input file indicator
Reference input file indicator
Bypass OMEGA
*The columns highlighted in gray are not used by the model's calculations.
Column A in the Scenarios worksheet indicates the ID number of the model run. From a
single scenario file, the model can run as many different scenarios as the user desires.
Column B allows the user to provide each scenario a unique name, which the model will
use in naming the output directory and files for each scenario.
Column C denotes the baseline year for each scenario. This is the year prior to the first
year of the first redesign cycle.
Column D indicates the type of standard or target (CO2 or MPG) the model will use for
compliance, and is not currently active in the model.
Column E is where the user designates which of the three TARF equations the model
should use. The model uses the TARF equations to determine the order of technology package
application on the different vehicle models. There are three TARF equations which are
summarized below and are described in detail on page 34.
1. Effective Cost = [Technology package cost minus fuel savings over the payback
period].
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2. Cost Effectiveness-Society = [Effective Cost] divided by discounted lifetime CO2
emissions.
3. Cost Effectiveness -Manufacturer = [Effective Cost] Divided by lifetime CO2
emissions.
Column F indicates the user's preference for type of function for the industry-wide GHG
level. There are four options for compliance targets: 1 = universal; 2 = piecewise linear; 3 =
constrained logistic.
Universal Target
The universal target option is a numeric designation which the manufacturers' average
fleet CO2 cannot exceed. For a universal standard (which could apply to cars, trucks or cars and
trucks combined), only the value listed in the first of each set of the four coefficients is used
(Labeled "A" in the header row of the Target worksheet).
Piece-wise Linear
The attribute-based linear target function is described by up to four coefficients and has
the following piecewise linear mathematical form:
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y =
A;FPFPmK
Where
A: Minimum level of CO2 target
B: Maximum level of CO2 target
FPmin: Footprint value where CO2 target reaches minimum value (i.e., intersection of
lower asymptote with slope)
FPmax: Footprint value where CO2 target reaches maximum value (i.e., intersection of
upper asymptote with slope)
FP: Vehicle footprint (square feet)
When inputting a piece-wise linear target into the Target worksheet, FPmin and FPmax should be
respectively entered in the C and D coefficient columns.
Example of Footprint-Based CO2 Piecewise Linear Target Function
Footprint (ft2|
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Logistic Curve Target
The footprint-based logistic curve (shown below) is described by four coefficients and
has the mathematical form described below.
T = A + (B - A]
FP-C \
, D
FP-C
Where A, B, and FP have the same definitions
as above
C: Footprint value at equation inflexion point
(i.e., midpoint)
D: The term which controls the rate at which
the CO2 target moves from the minimum to
maximum values. High values of D cause the
curve to move slowly (in terms of footprint)
from the minimum to maximum target (i.e., a
sort of "inverse slope")
FP: Vehicle footprint
Example of Footprint-Based CO2 Logistic Target Function
Footprint (ft2)
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Column G of the Scenarios worksheet in the Scenario input file is entitled "fleet type."
There are two acceptable values for cells in this column: 1 = 1 fleet and 2 = 2 fleets. If 1 is
chosen, the standard defined in the "Targets" worksheet will be taken from the "Car" standard
section and applied to all of the vehicles listed in the market file, whereas if 2 is chosen, the
standards will be defined by both the "Car" and "Truck" standard sections and applied to cars
and trucks separately.
Column H contains the number of redesign cycles the model considers in a given run.
There can be as few as one redesign cycle and as many as eight. The model allows any length to
be assumed for a redesign cycle, as long as the redesign cycle length is the same for all vehicles.
The inputs should be designed appropriately to reflect the user's assumptions.
Column I contains the number of CCM iterations to be done in an effort to stabilize, or
get convergence, on vehicle sales changes.
Column J contains the limit (in units of g/mi CCh) imposed on the trading of compliance
credits between cars and trucks.
Columns K-N indicate which files the model will access for the different runs. Column
K contains the name of the market input file; column L contains the name of the technology
input file; column M contains the name of the fuels input file; column N contains the name of the
Reference file. All files must be in the same directory as the scenario file.
Column O contains a no/yes (0/1) indicator for whether or not to bypass OMEGA in
running the Consumer Choice Model.
The Scenario input file also contains the economic parameters that the model uses to
calculate the TARF equations. Such economic data is contained in the "Economics" worksheet
and is organized as illustrated in Table 7.
Table 7 - Input Data Contained in the Economics Worksheet of the Scenario File
Column(s)
A
B
C
D
E
F
G
H
1
J
Contents
Scenario ID number
Discount rate
Payback period
CAFE fine
Gap
Threshold cost
CCh value increase rate
EPA Lifetime VMT- Car
EPA Lifetime VMT- Truck
Market size
Column A contains the ID number for the model run, and it must be identical to that in
Column A of the Scenarios worksheet.
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Column B contains the discount rate for future dollar values. The model uses the
discount rate in the TARF calculations when calculating the fuel savings over the payback
period.
Column C designates the payback period over which consumers are believed to consider
fuel savings when purchasing a vehicle.
Column D indicates the value of a fine for non-compliance. EPA typically records $0
into this column. Changes to this value will affect the TARF, but not allow fine payment.
Column E contains the gap, which is the percentage difference between on-road fuel
economy and test cycle fuel economy. This value is important because compliance is based on
test cycle CO2, whereas the true impact on climate is based on the on-road CO2 and consumer
fuel savings are based on on-road fuel economy. The model uses this difference to convert test
cycle CO2 emissions to on-road fuel economy and calculate fuel savings in the core model's
TARF equations, as described further on page 34 below.
Column F contains the value for the "threshold cost". This value determines whether the
model will accept some degree of over-compliance when it determines the degree of technology
addition needed for a manufacturer to meet a standard, or if it will reduce the addition of
technology so that a manufacturer just barely complies. Specifically, if the per vehicle cost of
the last technology added by the model in order to reach compliance exceeds the threshold value,
the model reduces the percentage of that vehicle's sales which receives that technology to just
the degree needed to enable compliance. If the per vehicle cost of the last technology added by
the model in order to enable compliance is below the threshold value, the model leaves the
percentage of vehicle sales receiving that technology at the technology penetration cap for that
technology.10
Column G represents the rate of increase in the real value of CO2 emission reductions over
time. This value is included since some studies have predicted that the real value of CO2
emission reductions will increase over time as the impact of global climate change increase. The
units of this term are percent per annum. This value is used in the Cost Effectiveness-Society
TARF described below.
Columns H and I contain the statutory lifetime miles driven by cars and trucks. These
values are used to calculate the credit trading ratio between cars and trucks. Because real VMT
tends to grow over time, but the VMT used in the credit trading equation is determined by
regulation, this value can differ from the VMT in the reference file (described below). For
example, the lifetime VMTs per vehicle for cars and trucks provided in EPA's current GHG
regulations are 195,264 and 225,865, respectively.11
10 This flexibility was included in the model to reflect the different ways in which manufacturers apply various
technologies. For example, when adding basic engine technology such as variable valve timing, the manufacturer
would generally convert the entire production volume of a specific engine to this technology. The production of two
otherwise identical engines, one with the technology and one without, would likely not be maintained. However,
with more extreme technologies, such as dieselization or hybridization, the manufacturer often maintains two
versions of the vehicle, one with and one without these technologies. By setting the threshold in between the costs
of these two examples, the model will reflect these two approaches to technology application on the part of a
manufacturer.
11 However, while the user may choose to model different statutory and accumulated VMT, differences in this
values can yield to counter-intuitive TARF values.
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The Target worksheet of the Scenario file contains the parameters describing the GHG
compliance targets required by the universal, piece-wise linear and constrained logistic functions
described above. The first 40 columns describe the car standards for up to eight redesign cycles,
if "2" fleets are selected in column G of the Scenarios worksheet. If "1" fleet is selected, then
the standards described in Columns A through AO apply to both cars and trucks. Similarly, the
next 40 columns (AP through CC) describe the truck standards for up to eight redesign cycles if
"1" fleet is selected. This second set of values is not used if "1" fleet is selected. This is
described in Table 8.
Table 8 - Input Data Contained in the Target Worksheet of the Scenario File
Column(s)
B-F
G-K
L-P
Q-U
V-Z
AA-AE
AF-AJ
AK-AO
AP-AT
AU-AY
AZ-BD
BE-BI
BJ-BN
BO-BS
BT-BX
BY-CC
Contents
Coefficients describing the CC-2 Standard for Design Cycle 1
Coefficients describing the CO2 Standard for Design Cycle 2
Coefficients describing the CO2 Standard for Design Cycle 3
Coefficients describing the CO2 Standard for Design Cycle 4
Coefficients describing the CO2 Standard for Design Cycle 5
Coefficients describing the CO2 Standard for Design Cycle 6
Coefficients describing the CO2 Standard for Design Cycle 7
Coefficients describing the CO2 Standard for Design Cycle 8
Coefficients describing the CO2 Standard for Design Cycle 1
Coefficients describing the CO2 Standard for Design Cycle 2
Coefficients describing the CO2 Standard for Design Cycle 3
Coefficients describing the CO2 Standard for Design Cycle 4
Coefficients describing the CO2 Standard for Design Cycle 5
Coefficients describing the CO2 Standard for Design Cycle 6
Coefficients describing the CO2 Standard for Design Cycle 7
Coefficients describing the CO2 Standard for Design Cycle 8
Vehicle Class
Car If "2" fleets
selected
Car and Truck if "1"
fleet selected
Truck If "2" fleets
selected
Not used if "1" fleet
selected
As indicated, each CO2 standard is described by up to five coefficients. For a universal
standard, only the value listed in the first of each set of four columns is used (Labeled "A" in the
header row of the Target worksheet). The first four columns are required to describe either the
segmented linear or constrained logistic functions described above.
E The Reference File: Vehicle Survival Rates and Miles Driven
The Reference file contains car and truck annual miles driven and survival rates by year.
These estimates are used in the cost effective TARF (1) and the cost effectiveness-society TARF
(2) calculations when determining fuel savings over the payback period and in the cost
effectiveness-manufacturer TARF (3) when determining the lifetime CO2 reduction. TARF 3
uses the statutory VMT values in the scenario file.
The vehicle survival and VMT estimates are inputted in the worksheet entitled Vehicle
Age. Column A in this worksheet contains the vehicle age in years. Columns B and C contain
the percentage of cars and trucks still projected to be on the road of the specified ages,
respectively. Columns D and E contain the average miles driven annually (per vehicle) for cars
and trucks, respectively, for vehicles of the specified ages.
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The Refrigerant worksheet contains data which is only used if refrigerant emissions are
included in the market file. A dynamic list of acceptable refrigerants can be created, and
accompanied with their respective global warming potential. Column A is the refrigerant name,
while column B is the GWP.
F Non-editable Input Data
The only values "hard-coded" into the model which are potentially used in the
application of technology to vehicles are the distribution of leakage rate by vehicle age.
The following table describes the refrigerant leakage rates which are currently hard-coded.
Table 9 - Refrigerant leakage rates
Refrigerant Leakage Fractions
Year
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
% of Total Lifetime
Leakage g/year
1.1%
1.5%
2.0%
2.4%
2.9%
3.3%
3.6%
4.4%
5.5%
6.9%
8.5%
8.1%
7.5%
7.0%
6.5%
6.0%
4.8%
3.9%
Year
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
% of Total Lifetime
Leakage g/year
3.3%
2.7%
2.3%
1.8%
1.4%
1.1%
0.9%
0.7%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
EPA intends to make this data editable in a future version.
G Input Files Currently Distributed with Model
The sample files bundled with the installation file contain example or "dummy" data and
are only indicative of realistic values. The input files from recent rulemaking analyses are
available on the EPA OMEGA webpage.
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IV Model Operation
A Calculating Technology Effective Basis (TEBs) and Cost Effective Basis (CEBs)
The market data input file utilized by OMEGA, which characterizes the vehicle fleet, is
designed to account for the fact that the vehicles which comprise the baseline fleet may already
be equipped with one or more of the technologies available in general to reduce CO2 emissions.
As described previously, OMEGA is typically used with technologies in packages, as opposed to
one at a time. However, actual vehicles are equipped with a wide range of technology
combinations, many of which cut across the packages. Thus, EPA developed a method to
account for the presence of the combinations of applied technologies in terms of their proportion
of the technology packages. This analysis can be broken down into four steps
The first step in the process is to break down the available GHG control technologies into
five groups: 1) engine-related, 2) transmission-related, 3) hybridization, 4) weight reduction and
5) other. Within each group we gave each individual technology a ranking which generally
followed the degree of complexity, cost and effectiveness of the technologies within each group.
More specifically, the ranking is based on the premise that a technology on a baseline vehicle
with a lower ranking would be replaced by one with a higher ranking which was contained in
one of the technology packages which we included in our OMEGA modeling. The corollary of
this premise is that a technology on a baseline vehicle with a higher ranking would not be
replaced by one with an equal or lower ranking which was contained in one of the technology
packages which we chose to include in our OMEGA modeling.
In the second step of the process, we use these rankings to estimate the complete list of
technologies which would be present on each baseline vehicle after the application of each
technology package. We then use the EPA lumped parameter model to estimate the total
percentage CO2 emission reduction associated with the technology present on the baseline
vehicle (termed package 0), as well as the total percentage reduction after application of each
package, including any baseline technology still expected to remain present after the application
of each package. Similarly, we use a cost estimation tool to estimate the cost of the CO2
reducing technology present on the baseline vehicle and after the addition of each package.
The third step in this process is to convert these total levels of emission control
effectiveness and cost to TEB and CEB12 values which can be used when the OMEGA model
applies technology packages on an incremental basis. This is done by comparing a given
vehicle's CO2 emissions if equipped with a given package and the incremental costs applied to
the given vehicle if equipped with the package. The value of each vehicle's TEB for each
applicable technology package is determined as follows:
12 As described earlier, the degree to which a technology package's incremental effectiveness is reduced by
technology already present on the baseline vehicle is termed the technology effectiveness basis, or TEB, in the
OMEGA model. The degree to which a technology package's incremental cost is reduced by technology already
present on the baseline vehicle is termed the cost effectiveness basis, or CEB, in the OMEGA model.
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TEBVii = (Baseline C02) x
(l - TotalEffectVii}
(1 - Totals ffecty)
Where
TotalEffectv.i = Total effectiveness of all of the technologies present on the baseline vehicle after
application of technology package i
TotalEffectv = Total effectiveness of all of the technologies present on the baseline vehicle
Baseline CCh = CCh value of the baseline vehicle (i.e., the given vehicle in the baseline fleet)
Equation A-l - TEB calculation
The value of each vehicle's CEB for each applicable technology package is determined
as follows:
CEBvi = TotalCostvi TotalCostv
Where
TotalCostv.i = Total cost of all of the technology present on the vehicle after addition of package i to
baseline vehicle v
TotalCostv = Total cost of all of the technology present on the baseline vehicle (/'. e., the given vehicle
in the baseline fleet)
Equation A-2 - CEB calculation
B Calculating Other Effectiveness Basis (OEBs)
As noted above, the market data input file utilized by OMEGA is also designed to
account for the fact vehicles may not have the exact equipment in the package after the package
is applied. This is particularly relevant in the context of a regulatory incentive for specific
technologies. As an example, if incentives are provided for start-stop systems, the model needs
to know whether that vehicle contains a start-stop system in order to provide the credit. If a
vehicle platform already contains start-stop before any packages are applied, the model needs to
account for the baseline credit impacts of the technology. As it varies at the vehicle level, rather
than vehicle type, this accounting needs to occur at the level of the market file rather than the
technology file.
However, it is important that the technology packages are ranked in the same order for all
vehicles in a vehicle type. Therefore, the TARF is calculated with the credit value in the
technology file, but the compliance CO2 value is calculated using the vehicle specific value.
C Platform Aggregation
The market file includes a vehicle Platform Index (see the description of the new
market.xls file layout in Section IIIA.) Vehicles with the same Platform Index share a common
Vehicle Type and engine configuration. While every entry in the market.xls file has a unique
Vehicle Index, several vehicles may share the same Platform Index. Vehicles in a single
platform should share vehicle class and vehicle type.
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In some analytical situations it is useful to have a market file with a single record for every
unique manufacturer / platform combination. This requires combining individual vehicles with
matching manufacturer / platforms into single representative records. Since OMEGA already
loads all of the information necessary to perform this calculation, EPA has chosen to include
creation of a manufacturer / platform version of the market file as a standard feature in the
model.
After loading the market file, OMEGA performs the necessary calculations and creates a
Platform Aggregation version of the market file, and then uses this new market file in the
subsequent OMEGA run. The new output data set is tab-delimited with a layout matching the
market.xls file (the output filename isX-Platform_Mfr.log, where Xdenotes the scenario name.)
Records in the manufacturer / platform file are created by calculating weighted average
values for the vehicle records with matching manufacturer and platform codes.
The following data elements in the market file are calculated as a sales weighted average
using the Annual Sales in Cycle 1:
CO2 (grams per mile)
Footprint (ft2 )
Curb Weight (pounds)
Displacement (Liters)
Horsepower
Max Seating
Towing Capacity (pounds)
Combined EC (kWh/mi)
Refrigerant Lifetime Leakage (grams)
CEB_Tech_l-CEB_Tech_50
Combined Miles per Gallon (harmonically averaged)
The following data elements in the market file are calculated as a sales-CO2 weighted
average using CO2 * Annual Sales in Cycle 1:
TEB_Tech_l-TEB_Tech_50;
OEB_Tech_l-OEB_Tech_50;13
Vehicle sales (baseline and annual sales) are the sum of sales in the individual vehicle
records. All other data elements are set equal to the values found in the first vehicle in the
manufacturer / platform set.
D Technology Application
The technology application portion of the model can be described in several steps. The
first step determines the effective CO2 emission standard for each manufacturer and vehicle
class. The second step converts the baseline lifetime refrigerant emissions specified for each
vehicle into its g/mi CO2 equivalent and adds this to the baseline tailpipe CO2 emissions for each
vehicle. The third step applies technology until this standard is met or all available technology
has been applied. These steps are described below.
13 This weighting will be changed to sales-weighted only in future model versions, which is consistent with the methodology
used in the MY 2017 and later light duty greenhouse gas rulemaking.
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D.i Determination of Manufacturer-Specific CO2 Emission Standards
As described above, three types of standards can be evaluated by OMEGA: universal or
flat, piecewise linear, and constrained logistic. Determining each manufacturer's effective
standard under a flat standard is simple; it equals the flat standard. The other two types of
standards require sales-weighting the CO2 target applicable to each specific vehicle model
produced by that manufacturer. Under these standards, the model calculates each vehicle's CO2
target by plugging the vehicle's footprint into the formula describing the standard. Each of the
vehicle-specific targets are then multiplied by the vehicle's sales in that redesign cycle and the
statutory lifetime VMT for that vehicle class and summed across all vehicles. The sum is then
divided by the sum of the product of vehicle sales by that manufacturer in that redesign cycle and
the lifetime VMT for each vehicle. The result is a sales and lifetime VMT weighted corporate
average CO2 target for each manufacturer's relevant set of vehicles (i.e., cars, trucks, or cars and
trucks combined).
If one fleet is specified, then the model only performs this calculation once and includes
both cars and trucks in the calculation. If separate standards are specified for cars and trucks,
then the model performs this task twice for each manufacturer for each redesign cycle being
modeled: once for cars and once for trucks. If the same standard is specified for both cars and
trucks and two compliance fleets are specified in the Scenario file, then two separate calculations
are still performed. The result is still two distinct CO2 emission targets, one for cars and one for
trucks.
If a trading limit of "0" is specified, then this stage of the model operation is complete. If
a non-zero trading limit is specified, an additional step is required to ensure that this trading limit
is not exceeded, as described in the section below on credit trading algorithms. Conceptually, we
assume that a manufacturer would prefer to evaluate the application of technology to both its
cars and trucks at the same time in order to optimize compliance (via the TARF) over the widest
set of vehicles. At the same time, the manufacturer is assumed to want to avoid generating
credits from one of its two vehicle class fleets which cannot be used by the other fleet due to the
limit on trading, since it would incur cost with no benefit.
D.ii Converting Lifetime Refrigerant Emissions to COi-Equivalent emissions per Mile
Refrigerant leakage emissions are input to the model in terms of lifetime emissions,
where refrigerant leakage increases with wear and tear of the A/C system. Leakage emissions
also occur during accidents, repairs and vehicle scrappage. Refrigerant emissions per year
increase significantly with age. Since annual mileage decreases with age in general, refrigerant
emissions per mile increase even more significantly with age than emissions per year. In
contrast, CO2 tailpipe emissions are input in terms of g/mi and are generally assumed to be
constant with age. Thus, some processing is needed to ensure that the leakage rates for the two
types of emissions are comparable.
OMEGA converts lifetime refrigerant emissions to their equivalent value in terms of CO2
emissions per mile (RCO2) considering the change in societal value of CO2 emissions over time.
The goal is to estimate a level of CO2 emissions per mile, which, if constant over the vehicle's
life, like tailpipe CO2 emissions are generally assumed to be, would produce the same societal
value of CO2 emissions as the distribution of refrigerant emissions over the life of the vehicle.
This equality is shown in the following equation:
27
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Equation 3 - Conversion of refrigerant emissions to equivalent lifetime emissions
Value of Equivalent Lifetime CO2 Tailpipe Emissions =
Value of Lifetime Refrigerant Emissions
L L
RC02* J][VMT1 *ValueofC02,] = GWP*^[Re/Leakage, *ValueofC02i]
i=l i=\
Where:
VMT; = the annual miles travelled for the relevant class of vehicle at age i, (e.g., VMTi =
Survival Fraction for a vehicle of age i times the annual vehicle miles driven for
a vehicle of age i as input in the Reference file),
L = the lifetime of the vehicle.
ValueofCOa = the societal value of CCh emissions in the calendar year when the vehicle
is at age i,
RefLeakagei = the annual rate of refrigerant emissions when the vehicle is at age i, and
GWP is the global warming potential of the refrigerant relative to CCh.
The value of CO2 in a particular year can be described as its base value divided by one
plus the applicable discount rate raised to the power of the age of the vehicle. In this case, the
applicable discount rate is the societal discount rate less the rate of increase in the real value of
CO2 emissions. Since the normal discounting equation assumes that the relevant activity (e.g.,
payment) occurs at the end of the year and emissions occur throughout the year, we multiply by
one plus half of the applicable annual discount rate. The resulting equation is described as
follows:
. DR-IR
1 + o
RCO2(glmi) *Yj[VMTi * BaseValueofCO2 x- ^-] =
i=i (1 + DR IR)
DR-IR
L 1 + -
GWP * Y [RefLeakage, * BaseValueofC02 *
* x
(I+DR-IR)'
This equation can be rearranged to solve for the level of CO2 equivalent emissions per mile as
shown in the next equation. (Note that the societal value of CO2 in the base year falls out of the
equation.)
28
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RCO2(g/mi) =
36
z
1=1
Leaki
36
z
1=1
DR-IR 1
9
P/7/Y1 V
(! + £>/?- //?)'
/>*-/*
VMT y ^
(i + DR - IR)'
xGWP
There are other approaches to converting lifetime refrigerant emissions to their g/mi
equivalent level. Future versions of OMEGA may provide the user with several approaches
from which to select. One approach would be to simply allow the user to specify a baseline
value for g/mi CO2 equivalent refrigerant emissions in the Market file. This way, the user could
use whatever approach was deemed appropriate to estimate this value. Another approach would
be the same as the above, except to base the equivalency on physical emissions and remove the
factors involving discounting. Therefore, if the user desires to perform this equivalency using
physical emissions, they should set the rate of increase in the societal value of CO2 emission
reductions to equal the overall societal discount rate being specified. This will cause all of the
discount factors in the above equation to be equal to 1.0. Then, if the user desires to use a
different rate of increase in the societal value CO2 emission reductions in the estimation of
benefits, they can change this value in the benefits calculation spreadsheet.
D.iii Application of Technology - Methodology
The portion of the model which applies technology can most easily be described as the
multiple application of three logical steps. The first step is to determine the vehicle in the "best"
position to receive the next technological improvement to enable the manufacturer to meet the
specified CO2 emission standard. The second step is to apply this technology, reduce the
vehicle's emissions accordingly and add the cost of this technology to the manufacturer's total
cost for this redesign cycle. The third step is to assess the compliance situation and act
accordingly. If the standard applies to cars only, trucks only, cars and trucks combined with a
single standard, or cars and trucks combined with two distinct standards and a zero trading limit
(i.e., no trading), the model will:
Recalculate the manufacturer's sales and VMT-weighted emissions and compare this new
corporate average emission level to the manufacturer's standard
o If the manufacturer is now below the standard, determine if the cost of the last
technology is above or below the threshold cost specified
if the cost is below the threshold, the evaluation of this manufacturer is
over and the model moves onto the next manufacturer;
If the cost is above the threshold, the percentage of sales which receive the
technology is decreased until the standard is just met; the evaluation of
this manufacturer is over and the model moves onto the next
manufacturer.
If the manufacturer is still above the standard, the model goes back to steps 1 and 2 above
and applies another technology package to further reduce emissions. If no more
technology packages are available, the model moves onto the next manufacturer.
29
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If a non-zero trading limit is specified, the model will follow largely the same procedure, but
additionally will consider the credit trading algorithms.
Once all manufacturers are in compliance or have exhausted the technology available for
their vehicles, the model moves to the next redesign cycle and repeats the above sequence of
steps. The evaluation of the second and any subsequent redesign cycles starts from scratch in
that every vehicle begins with only those technologies present in the Market file. In other words,
the model does not start with the technology added in previous redesign cycles. The assumption
behind this aspect of the model is that manufacturers have the flexibility to reevaluate technology
each time a vehicle is being redesigned. This could involve the evaluation of a technology which
was not available in the prior redesign cycle or a technology which had a maximum penetration
cap of less than 100%. Of course, starting the analysis over each redesign cycle could lead to
situations where a manufacturer is projected to utilize several very different technologies for
most of their vehicles in each of several redesign cycles. The user would have to evaluate the
reasons for such an outcome and determine if the inputs were reasonable or required
modification.
The application of technology, described conceptually above, is described in more detail
below. In the following formulae, the subscripts (t-1) and (t) indicate vehicle conditions before
and after applying technology package "t", respectively.
D.iii.a Use of Technology phase in "Caps"
OMEGA tracks CO2 emissions by fuel and at each package application step within each
vehicle. Conceptually, a vehicle platform is composed of vehicles, each with its own fuel, CO2
emission rate and energy consumption rate. When a technology is fully available (when its cap is
100%), it can be applied to all vehicles within a platform. However, when the cap is less than
100%, OMEGA applies the technology to only a portion of the vehicle platform. An example
follows (Figure IV-1).
30
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Figure IV-1 - Application of packages
Example A:
A package with cap of 100% & effectiveness of 50%
Platform A
Emission Rate
Sales
300g/mile
100
Platform A
Emission Rate
Sales
150g/mile
100
Example B:
A package with cap of 50% & effectiveness of 50%
A-l
Emission Rate
Sales
300g/mile
50
Platform A
Emission Rate
Sales
300g/mile
100
A-2
Emission Rate
Sales
150g/mile
50
This model feature simplifies the ability to apply technology packages which have caps
of less than 100%. By effectively treating the cap limited packages as separate segments within
a platform, we simplify the addition of subsequent technologies to the subset of vehicle sales
with this technology and those without it.
Applying the caps at the vehicle platform level is consistent with our platform based
approach, in that many cap limited technologies would not necessarily replace all instances of
other technologies on a platform. As an example, consider a hybrid package, which is often
offered in parallel to a conventional engine package.
D.iii.b Credit Trading
As the Clean Air Act allows credit trading between a manufacturer's car and truck fleets,
OMEGA allows the user to utilize a full range of credit trading scenarios. This trading is
controlled in OMEGA in column I of the scenarios worksheet of the Scenario input sheet.
Entering a zero into this column prevents credit trading and requires manufacturers to comply
with the relevant emission standards for their cars and its trucks separately. If the user wants to
allow unlimited trading, this is accomplished by inputting a large non-zero number in Column I
(e.g., 1000 g/mi CO2). This effectively allows the model to apply technology across both cars
and trucks and meet the combined standard described above. We say "effectively", because the
model still checks to ensure that the trading limit is not triggered and this cannot be definitively
31
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determined until compliance is achieved at the end of the evaluation of this manufacturer.14
Thus, in addition to requiring compliance with the fleetwide average CO2 target, the model must
also ensure that each fleet complies with its applicable target plus the trading allowance.
Should a non-zero number be entered in column I, OMEGA determines the overall sales-
and VMT-weighted emissions target for the manufacturer with cars and trucks combined:15
Salescars x Standardcars x Regulatory VMTCars +
T Salestrucks x Standardtrucks x Regulatory VMTtrucks
argetmfr - Salescars x Regulatory VMTCars +
Salestrucks x Regulatory VMTtrucks
The model also determines the starting point for each manufacturer using the same basic
equation
Salescars x Base emissionscars x Regulatory VMTCars +
. . _ Salestrucks x Base emissionstrucks x Regulatory VMTtrucks
Base emisswnsmfr - Salescars x Regulatory VMTCars +
Salestrucks x Regulatory VMTtrucks
Credits are generated when a manufacturer's fleet of either cars or trucks overcomplies
with the applicable standard. The amount of credits generated equals the difference between the
sales weighted average emission level for that vehicle class and the applicable standard
multiplied by the lifetime VMT per vehicle for that vehicle class. For either vehicle class, in
aggregate, the generated credits are calculated by the equation below.
Credits Generated
= (Sales x Regulatory VMT x C02 emission standard)
(Sales x Regulatory VMT x C02 emission average)
Where
Sales = Sales volume of each car or truck in that redesign cycle,
Regulatory VMT = Lifetime VMT per vehicle according to regulation (from the reference file).
CO2 emission standard = The target set in the scenario file
CO2 emission average = The achieved CCh level for the vehicles after the application of technology
Credit use is determined by the same formula, except for the substitution of the vehicles
from the other vehicle class, as shown below.
Credits used = (Sales x Regulatory VMT x C02 emission standard)
(Sales x Regulatory VMT x C02 emission average)
Where
Sales = Sales volume of each car or truck in that redesign cycle,
14 If the trading limit is greater than the emission standard, trading is effectively unlimited.
15 VMT weighting allows the user to account for the difference in miles driven between difference classes of
vehicles and provides for environmentally neutral credit trading:
32
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Regulatory VMT = Lifetime VMT per vehicle according to regulation (from the reference file).
CO2 emission standard = The target set in the scenario file
CO2 emission average = The achieved CCh level for the vehicles after the application of technology
OMEGA utilizes a simple set of algorithms to determine the correct distribution of
technology between car and truck fleets. OMEGA calculates the level of sales and VMT
weighted emissions of either car and truck emissions which will generate the maximum
allowable use of credits by the other vehicle class (the "lower limit"). It then tracks sales and
VMT weighted car, truck and combined emissions when adding technology. When the sales and
VMT weighted average emissions for either cars or trucks reaches this lower limit, no additional
technology is applied to that vehicle class. Technology is only applied to the other vehicle class,
as this latter class still exceeds the level of its standard plus the allowable trading level.
For example, assume a trading limit of 10 g/mi CO2 is input and the applicable car and
truck standards for a manufacturer are 220 and 300 g/mi CO2, respectively. The model
calculates the combined sales and VMT weighted CO2 emission target using the above equation
for FleetwideCO2Target, which can be simplified as follows:
£ (Sales v x LifeVMTv x Targetv )
Fleetwide CO 2 Target = ^
^SalesvxLifeVMTv
vc=l
Where vc represents the two vehicle classes, cars and trucks.
Once the Fleetwide CO2 Target is known (assumed to be 260 g/mi in this example), this
same equation can be used to determine the level of average car emissions which achieves
compliance when the level of average truck emissions exceeds its target by 10 g/mi CO2 (310
g/mi in this example). For this example, assume this level is 198 g/mi CO2. Any level of
average car emissions between 198 and 220 g/mi produces credits for trading which can be
effectively utilized towards compliance by trucks. Likewise, the minimum level of average truck
emissions which produces useful credits for use towards compliance by cars is determined which
achieves compliance when the level of average car emissions exceed its target by 10 g/mi CO2
(230 g/mi in this example). Again, for this example, assume this level is 290 g/mi CO2.
The model then proceeds to add technologies to cars and trucks (described in greater
detail below) until one of three criteria is met:
1) combined car and truck emissions reach 260 g/mi CO2,
2) car emissions reach 198 g/mi CO2, or
3) truck emissions reach 290 g/mi CO2.
If combined car and truck emissions reach 260 g/mi CO2 before the other two criteria are
met, the evaluation of this manufacturer is complete. The manufacturer complies with the sales
and VMT weighted standard applicable to cars and trucks combined and any level of trading
implied is less than the maximum allowed. If criterion 2 is reached first, the model continues to
evaluate and apply technology, but only to trucks. In this case, the model continues to
effectively add technology to trucks only until criterion 1 is met (unless insufficient technology
33
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exists to enable overall compliance). Likewise, if criterion 3 is reached first, the model continues
to evaluate and apply technology to cars.
Fleetwide total tailpipe and refrigerant CO2 equivalent emissions are determined in an
analogous fashion. Compliance is achieved when fleetwide total CO2 is equal to or less than the
fleetwide CO2 Target.
D.iv Technology Application Ranking Factors
The Technology Application Ranking Factor (TARF) is used to rank the application of
available technology packages across various vehicles. As described above, the user can choose
between three different TARF equations for ranking technology application: 1) Effective Cost, 2)
Cost Effectiveness-Society, and 3) Cost Effectiveness-Manufacturer. The first and third TARF
equations take the view of the manufacturer in determining the application of technology. This
can be deemed appropriate since the manufacturer controls the decision making process. Since
the manufacturer must satisfy its customers and regulatory mandates, a manufacturer's decision
making processes will reflect these needs, as well. More explicitly, the technology cost is
assumed to be the full cost of that technology at the consumer level, including research and
development costs, amortization of capital investment, etc. This cost is generally the same cost
as EPA estimates in its regulatory support analyses when estimating the cost of new standards.16
This cost is not necessarily the increment in price that the manufacturer would charge for that
technology, since price is a function of many factors which can change fairly quickly depending
on market conditions. The fuel savings of interest are those assumed by a manufacturer to be
valued by the customer, so they are based on fuel prices including taxes and reflect the
timeframe which a customer might consider when purchasing a vehicle. The residual value of
the added technology is not currently reflected in either TARF, but could be added in the future.
While the first and third TARFS take the veiew of the manufacturer, the second TARF
takes the view of society in deciding which technologies should be added first. This distinction
will be described further below. In all three cases, the vehicle with the TARF with the most
negative value is applied first.
D.iv.a Effective Cost TARF (TARF No. 1)
The Effective Cost TARF (EffCosf) is defined as the cost of the technology (TechCosf)
less the discounted fuel savings over a specified payback period of vehicle use. The Effective
Cost TARF was included in the OMEGA model, since it is the equivalent of the technology
ranking process used in NHTSA's CAFE compliance Model. It allows a user to match this
aspect of the Volpe Model when modeling equivalent standards using both models, if this is
desired. Quantitatively, it is defined as follows:
EffCost = TechCost -FSx ! CAFEFine
(I-GAP)
TechCost is the cost of technology t per vehicle, as input in the Technology file. Fuel
consumption per mile (over the compliance test cycle used to determine compliance with the
input CO2 emission standards) before (FCt-i) and after technology addition (FCt) is calculated as
follows:
16 See Section III.H of the Draft Regulatory Impact Analysis to the recent EPA NPRM for the control of GHG
emissions from cars and light trucks for a discussion of technology costs at the manufacturer and consumer levels.
34
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CD,.
44gCO2
llgC
FC=-
C02
TARF,t
CD.
44gCO2
12gC
Where:
and CDt
CO2
= the carbon density of the liquid fuel (in terms of grams carbon per gallon) before
and after technology application.
= the level of tailpipe emissions prior to the application of the technology being evaluated
(i.e., after the application of technology t-1), and
= the level of tailpipe emissions after application of technology t, without considering
any cap on the level of the penetration of technology t.
44g CO2/12 g C = the mass ratio of CO2 to C, used in converting the carbon density of a fuel to
an emitted mass of carbon dioxide.
CO
2TARF,t
CO2t-i is the actual level of CO2 emissions from the particular vehicle which would occur
after the application of all the technologies prior to technology t, considering both the fact that:
1) some or all of these technology packages may already be present on this vehicle (i.e., the
TEBs), and 2) there may be caps on the application of one or more of these technology packages
which are less than 100%. This level is the appropriate "baseline" CO2 level from which to
evaluate technology t since all previous technologies must be added to the vehicle before
technology t can be added.
Please note, that the TARF equations are defined on a per vehicle basis. Consequently,
OMEGA does not factor in the potential cap on the level of the penetration of technology t into
the TARF calculation.1? Because the calculation of CO2TARF,t does not consider the impact of
any cap on technology penetration, this level of CO2 emissions will differ from the CO2 emission
level of the vehicle should this technology be selected for addition. The equation for the latter
CO2 emission level is described further below. In order to be consistent with the calculation of
CO2TARF,t, the technology cost (TechCosi) is also determined without consideration of the
presence of the technology on the vehicle (via the value of CEB) and without consideration of
the cap on the penetration of the technology. Thus, TechCost is simply the incremental cost of
the technology listed in the Technology file.
17 Amortized capital costs tend to be higher for technologies which are applicable to lower production volumes.
However, the capital investment of many technologies can be spread across more than one vehicle model. Thus,
incorporating the capital investment associated with technology into the TARF would not be a simple matter. If
explicit consideration of capital costs is added to the model's operation in the future, both the cap on application of a
particular technology and the sales volume of the vehicle model will likely be relevant and included in the revised
TARF. The net result is that the cost of each technology should represent that for the timeframe and expected
production volume for each redesign cycle.
35
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With these premises, the formulae describing tailpipe CO2 emissions and refrigerant
emissions after the application of this technology package are as follows:
CO2TARF,t = CO2t_x x (l - AIE,)
Please note that the TEB term is not included when calculating TARFs. This is to
maintain consistency with the ranking process, which also does not include TEBs.
GWPt
GWPtA
The ratio of GWPs reflects the fact that the technology might change the refrigerant used
and affect the conversion of refrigerant mass emissions to CO2 equivalent emissions.
Fuel savings without consideration of the gap between on-road and certification fuel
economy (FS) is calculated as follows. Vehicles can have up to two separate energy sources, a
liquid fuel (subscript "1" in the equation) and electricity (subscript "2" in the equation ), as
would be the case with plug in hybrids.18
Y+PP
FS = y [(fuelCost0 + elecCost0) (fuelCostn + elecCostn~)]
i=Y
Y = cycle no * 5
PP = payback period [yrs]
fuelCosto = fuel cost with original technology
elecCosto = electricity cost with original technology
fuelCostn = fuel cost with new technology
elecCostn = electricity cost with new technology
Where energy costs are:
Y+PP
fuelCost0 = V
Y+PP
elecCost,
=1
FP0\y + (cy - 1) x 5] x FC0 x VMTy x
EP0\y+ (cy - 1) x 5] x EC0 x VMTy x
1 +
1 +
DRV
DR,
DRV
18 For purposes of calculating TARFS, the CCh credit values from the technology files are treated as both generating
CO2 reductions and fuel savings. This equivalency is required for two reasons. First, from the manufacturer's
perspective, the 62 credit does provide real COa benefit towards their CCh compliance goals. However, as will be
seen in the next section, providing CC>2 benefit without increasing fuel savings in the TARF can provide perverse
results, where the denominator is increased, but the numerator of the TARF stays constant. Having the credit
generate "fuel savings" in the TARF, is a work-around for this issue.
36
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FC
EP
EC
VMTy
DRy
t n
o
i
I Trr
fuelCostt = y
Pnly + (cy - 1) x 5] x FCt x 7M7y x L
1
m
T
elecCost,
I Trr
'-I
Pn [y + (cy - 1) x 5] x ECn x VMTy x
(DR,
1 + (^
)i
1 +
= fuel (liquid) price [$/gal]
= fuel (liquid) consumption [gpm]
= electricity price [$/kWh]
= electricity consumption [kWh/mi]
= vehicle miles of travel in year y
= discount rate for year y
= current technology
= original technology from tech-apply step (or baseline)
= year index
Annual fuel prices for both fuels (liquid & electricity) are used
CAFEFine is the fine a manufacturer pays for failing to meet the CAFE target. The equation for this is:
CAFEFine = FEE x
x
Where:
FEE
CAFEFCo
CAFEFCt
CAFEFCavg
Co2target
CDgas
CAFE_LFeqv
CAFE_ELeqv
FC
SFcls \CAFEF CavQ CAFEFCavQ - SFcls X (CAFEFCt - CAFEFC0}\
= CAFEFee [$/mpg]
= Sales fraction of vehicle in its class, for a given Manufacturer
=FC0 xCAFE_LFeqv
(CAFE Weighted Fuel Consumption for baseline technology [gpm])
=FCt xCAFE_LFeqv + ECt x CAFE_ELeqv
(CAFE Weighted Fuel Consumption for current technology [gpm])
= Coaarget x ( 12/44) / CDgas
(Manufacturer's CAFE Fuel Consumption at the beginning of redesign cycle [gpm])
= manufacturer' s CCh target [g/mi]
= carbon density of gasoline [g/gal]
= CAFE equivalence factor for liquid fuel [gal/gal]
= CAFE equivalence factor for electricity [gal/kWh]
= fuel (liquid) consumption [gpm]
= current technology
= original technology from tech-apply step (or baseline)
A positive value for this TAKF indicates that the consumer might view the vehicle less
desirably with the technology than without. A negative value for this TARF indicates that the
37
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consumer might view the vehicle more desirably with the technology than without.19 This
TARF assumes that manufacturers will incrementally add technologies which increase this
desirability to the maximum extent possible.
D.iv.b Cost Effectiveness-Society TARF (TARF No. 2)
The Cost Effectiveness-Society TARF (CostEffSoc) is identical to the Cost Effectiveness-
Manufacturer TARF (TARF 3) with one exception. The Cost Effectiveness-Society TARF
divides the Effective Cost TARF by the discounted lifetime CO2 emission reduction instead of
the lifetime CO2 emission reduction. The discount rate used would be for the value of CO2
emission reductions over time. The rationale for discounting is simply that society is presumed
to value CO2 reductions in this way. Also, in this case, we would recommend that the user
increase the payback period for fuel savings to cover the life of the vehicle instead of the much
shorter period of time often assumed to be considered by consumers when purchasing a vehicle.
Society values fuel savings over the life of the vehicle and not just for the first few years of use.
The user could also estimate technology costs from a societal point of view if this produced
different cost estimates than those used above. The Cost Effectiveness- Society TARF can be
described mathematically as follows:
(1 - Gap)
CostEffSOC = EffCost x
C02Saving
Where EffCost is defined using the equation in TARFi
Where CO paving is:
C02Saving = dC02x sumVMT
dCO2 = delta CO2 as calculated in TARF3
sumVMT = discounted present value of lifetime VMT using the VMT schedules from the reference input
file
Where sum VMT.
n
^ 1
1-
sumVMT = J VMTy x
^T
VMTy = VMT in year y
« = vehicle lifetime
DRy = discount rate [%] for year y
IR = CO2 value increase rate [%]
19 Of course, the calculated TARF values are dependent upon the assumed views of consumer valuation of fuel
savings, the payback period assumed, the discounting over that payback period, and other factors.
38
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D.iv.c Cost Effectiveness-Manufacturer TARF (TARF No. 3)
The Cost Effectiveness-Manufacturer TARF represents the degree to which consumer
desirability might change with the technology on a per ton of CO2 controlled basis. The
Effective Cost TARF ignores the degree to which the technology moves the manufacturer closer
to compliance. Thus, a fairly expensive technology which produces a large fuel savings might
have a fairly large negative Effective Cost TARF. The sequence of several less expensive
technologies with smaller fuel savings might all have less negative Effective Cost TARFs and so
would not be chosen over the more expensive technology. However, in total, the sequence of
smaller steps might achieve the same overall emission reduction as the more expensive
technology at a lower cost. The Cost Effectiveness-Manufacturer TARF would divide these less
expensive technologies by smaller CO2 emission reductions, thereby imrpoving their TARF
values relative to the more expensive technology. This would allow the model to choose the
sequence of less expensive technologies over the single expensive technology if their increase in
effective cost per ton of CO2 reduced was higher.
The Cost Effectiveness-Manufacturer TARF (CostEfJManuf) incorporates all of the terms
included in the effective cost TARF, but also accounts for the degree that the technology brings
the manufacturer closer to its CO2 standard. It can be described simply as the Effective Cost
TARF divided by the mass of the CO2 equivalent emission reduction over the life of the vehicle
due to addition of the technology. The Cost Effectiveness-Manufacturer TARF can be described
mathematically as follows:
CostEffManuf = EffCost / C02Saving
Where EffCost is defined using the equation in TARFi
Where CO paving is:
C02Saving = dC02 x LifeVMT
life VMT = lifetime VMT for a vehicle
Where dCO2 is:
dC02 = ((tpC02o - tpC02n) + (rfC02o - rfC02n) + (grC02o - grC02n) + (crC02o - crC02n))
tpCO2 = tailpipe CO2
rfCC>2 = refrigerant CO2
grC02 = grid CO2
crCO2 = CO2 credit
o = original technology from tech-apply step (or baseline)
n = new Technology
Where tpCO2ti is:
39
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tpC02n = tpC02o x (1 - AlE}
tpCO2O = original technology from tech-apply step (or baseline)
AIE = average incremental effectiveness of the new technology
Where rfCO2n is:
rfCO2o
refrigEff
GWP
rfC02n = rfC02o x refrigEff x GWP
= original refrigerant from tech-apply step (or baseline)
= refrigerant effectiveness
= global warming potentials (varies by refrigerant)
Where grCO2n is:
kWhMi
CD
Cr
grC02n = kWhMi x CD x Cr
= kilo-watt hours per mile of travel
= carbon density (gC/kWh)
= CO2/C ratio for electricity = 44.0 / 12.0
D.v Applying Technology - Calculations
As described above, for any individual vehicle, technologies are applied in the order in which
they are listed in the Technology file for the relevant vehicle type. Thus, at the beginning of the
evaluation for a manufacturer, the only technology which is available to each vehicle is
technology package 1 for its vehicle type. Thus, the OMEGA model compares the TARF
equations for applying technology package 1 to all of the vehicles in that manufacturer's fleet
and chooses the vehicle with the most negative TARF. The model then applies technology
package 1 to that vehicle and reduces its GHG emission level. The formulae for calculating the
new tailpipe and refrigerant CO2 emission levels after application of the technology are shown
below:
C02t=-
t_^ x (l - CAP x AIE]
1 - AIE x TEB
RC02t =
RC°2t-i X (l - CAP x AIE) GWPt
1 - AIE x TEB
GWP,
Here, both the presence of the technology in the baseline configuration of this vehicle and
the cap on technology application are considered. The terms shown in the denominators of both
equations are included due to the definition of the incremental effectiveness of technology.
When calculating the effectiveness of a technology, the user should assume that the vehicle to
which this technology is being applied has all of the previous technology packages applied, but
none of the additional technologies included in the technology of interest. Thus, the incremental
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effectiveness of hybridization over an advanced gasoline engine and transmission package might
be 10%. If a specific vehicle or more likely group of vehicles already reflected half of this 10%
hybrid benefit, it would not be correct to simply reduce the effectiveness of the hybrid package
to half of the 10% (i.e., 5%) and multiply base emissions by 0.95. It is more accurate to remove
the effect of the partial hybridization by dividing by 100% minus 5% (i.e., 0.95) and then
multiplying by 100% minus 10% (i.e., 0.9). The net effect in this case is to multiply base
emissions by 0.9474, which produces a slightly greater emission reduction than multiplying by
0.95. For modest technologies, the difference is small. However, for technologies which might
reduce emissions by 30% or more, the difference in methodology becomes more significant. See
the section discussing calculation of TEB values.
The model also adds the cost to the manufacturer's running total cost and recalculates the
manufacturer's corporate average emission level. The formulae used to perform these two
calculations are as follows:
Equation 4 - calculation of compliance COi value
C02 = Techpack C02 + Grid C02 + Refrigerant C02 + OEB
Equation 5 - Total Cost Calculations
TotalCostt = TotalCostt -1 + TechCost x (1 - CEB) x Salesv
Equation 6 - Fleet Average COi calculations
_ *v x Life VMTV x TCO21 ]
FleetTCO, , = -^
2 step
Where:
v = a vehicle produced by the manufacturer,
V = the total number of vehicles (cars, trucks, or both) produced by that manufacturer,
TCO2t= the emissions of the vehicle after application of the technology
LifeVMTv = the lifetime VMT of the class of vehicle to which vehicle v belongs. Lifetime VMT is statutory
VMT as given in the scenario file.
As mentioned above, compliance with the CO2 standards is performed on a sales and
VMT weighted basis, for ease in trading between cars and trucks under the provisions of the
proposed CO2 standards.
At this point, the model checks to see if the manufacturer is in compliance with its CO2
emission standard. If so, it stops and moves on to the next manufacturer. If not, the model then
evaluates the TARF for the next technology package for the vehicle which just received the last
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technology package. The model calculates the TARF for this package and compares it to the
TARF equations for the technology packages 1 for all of the other vehicles. This sequence of
adding one technology package to one vehicle, reevaluating compliance, and so on, continues
until either the manufacturer complies or until all the available technologies have been applied.
When either of these two endpoints is reached, the model moves to evaluating the next
manufacturer or the next redesign cycle.
The model keeps track of a number of intermediate values throughout the process of
adding technology. These include the order of technology application, the TARF equations for
each combination of vehicle and technology, the cumulative cost per vehicle, etc. for use in
producing the various output files.
V Output Files
A Summary of Outputs
The model places each scenario output in a separate subfolder. The name of each of
these files includes the name of the scenario listed in Column B of the Scenarios worksheet of
the Scenario file. Each of these output files and their purpose are summarized in the table below.
The main output files are also discussed in greater detail later in this section.
Table 10 - Summary of Model Outputs
File*
Summary Description
Main Output Files
X.log
X.xls
X-TechnologyTracking.xls
X-Techpacksales.log
X-vhl.xls
X-vh2.xls
Step by step details of the model operation including tech
pack application, cost, COz, and electricity.
Summary file that includes manufacturer specific details on
tech pack application, cost, CCh and electricity.
Details of the technology application rates by vehicle,
platform, manufacturer and vehicle type
Details on the sales of vehicles by tech pack at the
completion of the scenario. Useful in tracking technology
application.
Summary of final cost, emissions, and electricity
consumption by vehicle
Step by step details of cost by technology pack application,
summarized by vehicle.
Diagnostic Output Files
X-DetailedCycleResults.xls
X_Platform_Mfr.log
X-TechPackSFx.xls
X-VehicleFuelBreakDown.xls
X-VehSteps.xls
X-FleetSafety.log
Summarized Manufacturer-Fleet results by Fuel type for
every cycle.
Data for a Manufacturer/Platform version of the Market.xls
file
Final Sales Fraction for each Tech Pack on every vehicle
Reports fuel-level summaries for every vehicle.
Lists the sales fraction and CCh emissions for each fuel type
Reports safety related results for each vehicle
Scenario Comparison Table
SummaryOutputResults.xls
Summary table comparing manufacturer-level results across
all scenarios in the scenario.xls file.
*X is substituted here for scenario name.
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A.i Log of Technology Application Steps - Text Format
This file depicts the process of technology application to each manufacturer's fleet and
shows the progress being made towards compliance with the specified standards. Please note
that the log has several different formats which depend upon the user options selected.
The beginning of the file lists basic information about the model user, the version of
OMEGA being used and the input files. It then presents the technology application information
by redesign cycle and within each redesign cycle by manufacturer and within each manufacturer
by vehicle class (i.e., cars first and then trucks). If a combined car-truck standard is being
evaluated, then only one set of technology application steps is presented which combines both
types of vehicles. At the beginning of each redesign cycle, the file describes the standard or
standards being evaluated. For universal standards, this means the standard itself. For footprint-
based standards, the four coefficients described in the input file are listed. The file then begins a
sequence of sections which apply to a single manufacturer and single vehicle class, as shown
below.
The first line lists the manufacturer, its starting CO2 emission level, its CO2 target or
standard for this scenario and the vehicle class (C for car or combine, and T for Truck). The
starting CO2 emission level is simply the base CO2 emission level of each vehicle weighted by
vehicle sales in this redesign cycle. The CO2 standard is either the universal standard listed in
the Scenario file, or the foot-print based CO2 standard applied to that manufacturer's vehicles.
The following lines list the step-by-step application of technology packages. Going
through the columns, step is simply a numerical counter following by a hyphen. Index identifies
the vehicle receiving the technology or package and refers to the vehicle number in the Market
file. Type shows the vehicle type for this vehicle. The first column labeled CO2 pipe shows the
tailpipe CO2 emissions prior to the application of technology. For the application of technology
package 1, this value is the base CO2 emission level shown in the Market file. For subsequent
packages, it is the CO2 emission level resulting from the application of the previous technology
package. The first column labeled CChtot stands for total CO2 equivalent emissions and is
analogous to CChpipe. CChtot equals CChpipe plus refrigerant emissions in terms of equivalent
CO2 emissions. Again, this is either the base refrigerant emission level or the refrigerant
emission level after application of the previous technology package. TP is the technology
package added in this step. TARF is the value of the TARF for this package applied to this
vehicle.
The second column labeled CChpipe shows the tailpipe CO2 emissions after the
application of the technology package. This value considers the efficiency of the technology
package, the cap on the percentage of sales which can receive the package, as well as the
percentage of that package already present on the vehicle (i.e., the TEB). The second column
labeled CChtot shows this value plus the level of refrigerant emissions existing after any control
which have been applied to these.
CChavg represents the corporate average CO2 emission level for this manufacturer and
vehicle class combination. It will generally decrease after each step of technology application
and show progress towards the manufacturer's standard. Occasionally, this value will remain
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constant. This could be due to round off. Or, the vehicle receiving the technology may have
already been completely equipped with that technology. In this case, the model simply holds
both emissions and costs constant when it applies the technology.
kWhavg represents the avg kwh/mile of electricity consumed by the fleet. This includes
both the baseline electricity and the additional electricity consumed by plug-in vehicles. To be
clear, this is the average electricity consumed over all miles, not simply the electrically powered
miles.
TotCost represents the cumulative cost in dollars per model year of the technology added
up to that point. The increment in this value from step to step is the product of three terms: 1)
the cost of the technology package being added, 2) the sales of the vehicle in this redesign cycle,
and 3) the cap minus the percentage of that package already present in terms of cost (i.e., CEB)
or zero, whichever is higher.
The very last step of technology addition for each manufacturer and vehicle class
combination may be shown twice, with "OC" following the second listing. In this case, this step
does not represent the addition of technology, but a backwards interpolation between the
previous two steps of technology addition which eliminates the over-compliance which usually
results from adding discrete technologies to specific vehicles. The presence of this interpolation
step depends on the value of the threshold cost input specified in the Scenario file and the cost of
the last technology package, as discussed above under Input files.
This file can be very useful both for diagnostic and analytical purposes. The presence of
the TARF values in the file can be useful in identifying technology packages which have relative
poor cost effectiveness followed by packages with better cost effectiveness. In general, the list
of TARF values should start out negative and become more positive with continued technology
application. The only exception to this should be when the same vehicle receives technology in
sequential steps. In this case, the TARF may become more negative in a successive step, since
the OMEGA model could not consider the more cost effective technology until it applied the
previous technology to that vehicle. When the user observes a series of technologies being
applied to the same vehicle in successive modeling steps, this indicates that separating these
technology packages provides little practical purpose in the model run. Worse, the relatively
poor cost effectiveness of the first of the series of technology packages may be causing the
model to add technology to other vehicles which have worse cost effectiveness than the
combination of packages for the vehicle in question. This sequence of technology package
additions to the same vehicle could also be an indication that the order of technologies might not
be appropriate (or there might be an error in one of the technology input values).
From an economic perspective, this file presents the increase in cumulative cost for each
manufacturer as its average CO2 level is reduced. If a sufficiently stringent CO2 standard (e.g.,
50 g/mi) is input to the model, manufacturers will not comply with the specified standard.
However, the model will apply all of the technology available to each vehicle. Thus, the file
represents a complete relationship between cost and emissions for each manufacturer. By
reading the information contained in this file into a spreadsheet or other program capable of
analysis, the user can quickly determine the cost for a wide range of CO2 standards without
rerunning OMEGA each time. Since the social costs and benefits of CO2 standards tend to be
relatively linear with CO2 level, it is possible to represent these costs and benefits with simple
linear equations. The user can then easily combine the relationship between manufacturer's
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emission levels and technology costs with social costs and benefits at an industry-wide level. It
would then be possible to solve for the industry-wide emission levels which maximized net
societal benefits, produced zero net societal benefit or met some other economic criteria.
Example:
The following table depicts a portion of the log file from an OMEGA model run.
CYCLE 1 Target Coeffs: (A=204.0, B=275.0, C=41.0, D=56.0) , (A=246.0, B=347.0, C=41.0, D=66.0)
Industry Baseline CChavg = 287.35, Target CChavg = 223.31, Fleet Type = 'C'
Step
1-
2-
3-
4-
5-
33-
34-
35-
36-
54-
55-
92-
93-
93-OC
Index
19
14
29
13
18
28
14
14
19
7
7
25
28
28
Type
6
6
13
10
10
2
6
6
6
5
5
4
2
2
CChpipe
405.13
403.17
446.63
392.46
389.46
232.56
372.63
357.54
375.33
325.61
300.75
250.33
217.03
217.03
CChtot
405.13
403.17
446.63
392.46
389.46
232.56
372.63
357.54
375.33
325.61
300.75
250.33
217.03
217.03
IP
1
1
1
1
1
1
2
3
2
2
3
2
2
2
TARF
-0.1266
-0.1264
-0.1261
-0.1255
-0.1253
-0.1106
-0.0904
-0.0973
-0.0901
-0.0615
-0.0779
-0.0457
-0.0426
-0.0426
CChpipe
375.33
372.63
412.62
362.57
359.8
217.03
357.54
305.57
355.62
300.75
250.06
212.85
203.45
216.53
CChtot
375.33
372.63
412.62
362.57
359.8
217.03
357.54
305.57
355.62
300.75
250.06
212.85
203.45
216.53
CChavg
286.92
286.61
286.61
286.44
286.28
267.17
267.01
266.49
266.21
244.96
243.95
225.84
221.06
223.31
kwhavg
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
TotCost
33,256,539
57,241,908
57,306,310
70,885,077
83,589,991
2,117,945,615
2,158,753,183
2,238,406,536
2,297,680,885
6,904,283,762
7,106,439,868
11,043,478,070
12,799,723,914
11,973,039,155
The first five technologies added to cars in this model run were all the first technology
listed for each vehicle type (TP = 1). The same is true for steps 6-32 (not shown). Step 33 also
adds the first technology available to vehicle 28. Step 34 adds the second technology available
to vehicle 14, while step 35 adds the third technology available to this vehicle. This sequence
demonstrates how the model evaluates the next available technology for each vehicle when
deciding where to add technology next. In this case, technology number 3 for vehicle 14 was
preferred over any of the second technologies for all the other vehicles. Examination of the
TARF values explains why this was the case.
The TARF for the technology number 2 for vehicle 14 was-0.0904, while that for
technology 3 was -0.0973. Thus, if-0.0904 was the lowest TARF for step 34, an even lower
TARF would have to be the lowest TARF in step 35. When it is observed that the model adds
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two technologies in a row to the same vehicle, the user should question whether the first
technology should be modified or the two technologies should be combined. The reason for this
is that, unless step 34 is the very last technology added to enable compliance, the model will
never simply add technology 2 to vehicle 14. Vehicle 14 will always receive either technology 1
or 3. The primary concern is that a relatively high TARF value for technology package 2 could
inappropriately inhibit the application of the combination of technology packages 2 and 3 to this
vehicle relative to the application of technologies to other vehicles.
In this case, the TARFs for technologies 2 and 3 are quite close. Thus, combining them
into one technology package would not produce substantively different results. The same
sequence occurs with vehicle 7 later in the run (steps 54 and 55 in the above table). In this latter
case, the difference between the TARFs is much greater. Combining the two steps may have
resulted in the earlier application of the two technologies than applying them separately.
The final three lines of the above table illustrate the interpolation that occurs in the
compliance determination if the cost of the last technology added exceeds the "threshold" input
in the Scenario file. After step 93, the manufacturer's corporate average CO2 level was 221.06
g/mi, while the standard was 223.31 g/mi. The model adjusted the manufacturer's corporate
average CO2 level to 223.31 g/mi by only applying technology 2 to a portion of the sales of
vehicle 28. This reduced the overall cost of compliance from $12.8 billion to $12.0 billion.
Mathematically, this is equivalent to interpolating between the average emissions (CChavg) and
cumulative costs of steps 92 and 93.
A.ii Summary of Cost and Emissions - Excel Format
This file presents a summary of vehicle and manufacturer costs and emission levels
resulting from a model run. The file contains summary information about the run, the model
user, the version of OMEGA being used and the values input on the first worksheet of the
Scenario file. The file then lists five types of information by manufacturer and vehicle class: 1)
vehicle sales, 2) total costs, 3) cost per vehicle, 4) electricity consumption, and 5) emission level
per vehicle.
The file continues by presenting the cost of the technology added to each vehicle and the
last technology package added to each vehicle. The last section of the file presents the series of
technologies added to each vehicle. For each technology, the file shows the step (for each
manufacturer-vehicle class combination) in which the technology was added, the vehicle's
emission levels before and after this technology and the incremental total cost of adding this
technology.
A.iii Summary of Technology Pack Distribution - Text format
This file lists the final distribution of technology packs applied to each vehicle, and takes
the form of a matrix of vehicles and technology packages, with the sales presented within the
matrix. This is useful information when calculating technology penetrations. As an example, if
40% of vehicle 7 sales receive technology package 6, then 40% of vehicle 7 sales have the
technologies in package 6.20
20 In rulemaking analyses, EPA typically uses a more detailed methodology to calculate technology penetrations.
This method is documented in Appendix F of the Interim Join Technical Assessment Report.
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A.iv VH1 / Final summary of Vehicle Attributes- Excel Format
The "VH1" file lists each vehicle, the final technology package applied to that vehicle,
the final cost, and various attributes about the vehicle. Most of these attributes are carried
through from the market data file, however some such as the CO2 emission rate and electricity
consumption are modified by the model. In many senses, this file is a lower level corollary of
the Excel summary file described in IV.B, and is useful for determining the average cost increase
for a class of vehicles.
A.vVH2 / Stepwise listing of Vehicle AttributesExcel Format
The VH2 file provides the cost and CO2 emissions of each vehicle after each technology
package is applied. Similar to the VH1 file, it is organized by vehicle.
VI Running the Model
Installing the model should add an "OMEGA" icon to the user's desktop. OMEGA is
started by double clicking on this icon. A graphic user interface (GUI) should appear in a few
seconds. The current GUI is simple and relies on the fact that all of the information needed to
run the model is contained in the input files.
Once the GUI appears, the first step is for the user to select the desired scenario file.
Click on "File" in the menu bar and choose "Open" from the drop down menu. A window will
open which displays the files contained in the model's input directory. Double click on the
desired Scenario file and the model will load the data contained in this file and that in the
Market, Technology, Fuel and Reference files specified in the Scenario file. The GUI will
update and display portions of the Scenario, Market and Technology input files. The GUI allows
the user to partially navigate through these three files in order to confirm that the correct input
files were specified in the Scenario file. When everything is loaded, the car icon will turn green.
By default, OMEGA saves output files in the Output subdirectory where the executable is
installed. However, the user can specify an alternative output directory by selecting File/Output
Files To... From there, browse to, and select, the desired output directory. As a reminder, the
selected output directory name will display in the GUI.
In addition to the standard results, the model can generate a number of outputs which the
user may select prior to running the model. Click on Log to see a drop-down list of selectable
outputs. The contents of these outputs are described in Section 4. The user selections are
"sticky", and will remain selected (or not) between OMEGA runs.
The user can now run the cases included in the Scenario file by clicking on the green car
button.
As the model is running, the lower left hand corner of the GUI will indicate progress
(e.g., processing Scenario 1 of 5, processing Scenario 2 of 5, etc.). If the Scenario file only
specifies one case to be run, when the model is done with this case, the log (text) file showing
the sequence of technology addition by manufacturer and by redesign cycle appears. This file, as
all of the output files, is automatically named with the case name from the Scenario file, with the
file type "log" added. If more than one case is run, the indicator in the lower left hand corner
will simply say "Done" and no log files are displayed.
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