Document ID: EPA-HQ-OAR-2010-0162-0305
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2010-11-30T05:00Z

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

        ANN ARBOR, MI 48105

                                                                        
                                        	      			                     

September 10, 2010

         OFFICE OF 

AIR AND RADIATION

MEMORANDUM

SUBJECT:	Process for Determining Class 2b and 3 Co2 Standard

FROM:	A. Neam, J. Cherry, Assessment and Standards Division

TO:		Greenhouse Gas Emissions Standards and Fuel Efficiency Standards
for Heavy-Duty Engines and Vehicles; Docket Number EPA-HQ-OAR-2010-0162

Introduction

The heavy duty (class 2b and class 3) pickup trucks and vans sold
currently in the United States, and those which are anticipated to be
sold in the MY 2014-2018 timeframe, are highly varied and satisfy a wide
range of needs.  Examples for these vehicle classes include vans that
can transport 15 passengers and pickup trucks that can tow over 20,000
pounds.  American consumers require many vehicle options to accommodate
their utility needs and preferences.  Recent volatility in oil prices
and the state of the economy have demonstrated that consumer demand and
choice of vehicles within this wide range can be sensitive to these
factors.  Although it is impossible for any organization to precisely
predict the future, a characterization and quantification of the future
fleet are required to assess the impacts of rules which would affect
that future fleet.  The historic perturbations in the U.S. economy and
especially in the automotive sector in recent years make such
forecasting particularly problematic, and so for this rulemaking, it is
assumed the future mix of heavy duty trucks and vans, and volumes of
heavy duty vehicles, will be the same as those in the 2008 model year,
the most recent relatively stable sales year.  In order to accomplish
this, manufacturers have provided details on their 2008 models and
volumes.  This data along with available emissions data was used to
determine the baseline fleet.  This document provides details of how the
baseline fleet was created, how the CO2 emissions for each vehicle was
determined, how the baseline and standard emissions curves for the fleet
were determined, and gives the phase in for the standard.

Why do the agencies establish a baseline vehicle fleet?

In order to calculate the impacts of proposed standards, it is necessary
to estimate the composition of the future vehicle fleet absent the
standards in order to conduct comparisons.  We have developed a
comparison fleet.  The first step in this process was to develop a
baseline fleet based on model year 2008 data.  EPA and NHTSA created a
baseline fleet in order to track the volumes and types of fuel
economy-improving and CO2-reducing technologies which are already
present in today’s fleet.  Creating a baseline fleet helps to keep, to
some extent, the agencies’ from adding technologies to vehicles that
already have these technologies, which would result in “double
counting” of technologies’ costs and benefits when modeling.  

The 2008 baseline vehicle fleet

Why did the agencies choose 2008 as the baseline model year?

The 2008 model year is the most recent model year for which the industry
had normal sales.  The 2009 model year data was available, but this
model year was disrupted by the economic downturn and the bankruptcies
of both General Motors and Chrysler.  There was a significant reduction
in the number of vehicles sold by both companies and the industry as a
whole.  These abnormalities made the 2009 model year data unsuitable for
use as a future fleet.  Therefore, the agencies chose to use the 2008
model year data as the baseline since it was the latest representative
transparent data set available.  

On what data is the baseline vehicle fleet based?

EPA used several sources to determine the composition, volumes, and
emissions of the vehicles in the fleet.  Though the composition and
volumes of the fleet are from the 2008 model year, some advances in fuel
economy technology have occurred since the 2008 model year, so emissions
data from newer vehicles (when available) was used to model the
emissions of the vehicles.  Representative emissions data from the 2008,
2009, and 2010 model year’s vehicles was used.

The source of the heavy duty fleet composition and volumes are the
automotive manufacturers.  Chrysler, Ford, and General Motors each
submitted product plans which included their fleet composition, details
of each unique (weight and capability) truck and van sold, and their
volume.  The manufacturers included the 2008 model year at the
agency’s request.

 There were two sources for the CO2 emissions data.  The first was
emissions data submitted by the manufacturers at vehicle certification. 
Manufacturers are required to submit city cycle emissions data when they
certify vehicle for sale in Federal states.  Manufacturers are also
required to submit highway cycle emissions data for vehicles that are
certified for sale in California.  Since not all vehicles were certified
for California sale, only a subset of emissions data was available from
the certification database.

The second source for CO2 emissions data is a test program run by EPA. 
EPA tested a number of vehicles to acquire data from vehicles that are
currently in service.  The vehicles chosen augmented the certification
data, to insure adequate CO2 values were available for modeling the 2008
model year fleet.

How were the 2008 vehicles CO2 emissions modeled?

Ideally, the light duty CAFE ADFE approach would have been used, but the
necessary data is not available for each heavy duty vehicle.  Also, many
years worth of fuel economy data was analyzed to determine the
coefficients of the light duty equation.  

Since the method that is used for CAFE was not available, a new method
was derived.   The 2008 model year vehicles CO2 emissions were modeled
using characteristics of each vehicle that relate to CO2 performance. 
Although other characteristics affect CO2 performance, the
characteristics available were test weight, axle ratio, and 4 wheel
drive vs. 2 wheel drive.  

In order to model vehicle CO2 emissions, data was acquired from both the
certification database and the test program that match the vehicle type
(truck or van), class (2b or 3), and engine.  Multiple vehicles were
examined to determine a factor that could be used with each of the
characteristics that were used to model CO2 emissions.

Two equations were determined, one for City CO2 and one for highway CO2.

They are as follows:

City CO2= {A + [(C-B) * D]} * { 1 + [((E/F)-1) * G]} + H

Where:

A=Base City CO2

B=Test_Vehicle_Test Weight

C=CurrentVehicles Test Weight

D=Weight Multiplier City 

E=Vehicle Axle Ratio

F=TestVehicleAxle Ratio

G=City Axle Multiplier

H= 0 if test and current vehicle have the same wheel drive

    = – City 2wd4wd Adder if test vehicle had 4wd and the current
vehicle has 2wd  

    =+ City 2wd4wd Adder if test vehicle had 2wd and the current vehicle
has 4wd

Highway CO2=  {I + [(C-B) * J]} * { 1 + [((E/F)-1) * K]} + L 

Where:

I=Base Highway CO2

B=Test_Vehicle_Test Weight

C=CurrentVehicles Test Weight

J=Weight Multiplier City 

E=Vehicle Axle Ratio

F=TestVehicleAxle Ratio

K=Highway Axle Multiplier

L= 0 if test and current vehicle have the same wheel drive

    = – Highway 2wd4wd Adder if test vehicle had 4wd and the current
vehicle has 2wd  

    =+ Highway 2wd4wd Adder if test vehicle had 2wd and the current
vehicle has 4wd

Combined CO2 is used to set the standard.  It is derived using the
following equations:

Combined CO2 =55% * City CO2 + 45% * Highway CO2

The MY 2014-2018 Standards

Heavy duty vehicles are required for many applications that are beyond
the capabilities of vehicles from the light duty fleet.  It is important
that the CO2 standard for heavy duty vehicles does not prevent them from
continuing to satisfy these needs.  The baseline data set used for the
2014-2018 model year standards was analyzed in many ways to determine
the best way to create a baseline and ultimately a standard.  

What criterion was examined for determining the Baseline?

In order to preserve the utility of heavy duty vehicles, many criteria
were evaluated to determine the input for the baseline equation. 
Examples include EPA curb weight, ALVW, Payload, GCW, GVWR, Footprint,
and Trailer Tow.  The definition for each is below.

EPA curb weight = curb weight of the vehicle with 33% of the optional
content added.

ALVW = EPA curb weight + ½ Payload

Payload = GVWR - EPA curb weight

GVWR = Gross Vehicle Weight Rating,

GCWR = Gross Combined Weight Rating

Footprint = Wheelbase – (Front Track Width + Rear Track Width) / 2

Trailer Tow = GCWR-GVWR

How was the criterion chosen for the Baseline?

The main applications for heavy duty vehicles include hauling
payload/people and/or towing.  Most of the criteria were evaluated
graphically with the exception of footprint.  After reviewing the
footprint data, it was obvious that footprint did not track well with
CO2 and the capability of heavy duty vehicles.  

CO2 was graphed vs. EPA curb weight, and it was observed that at the
same weight, vehicles can vary several hundred grams per mile of CO2. 
This is due to the fact that at the same curb weight, vehicles can have
both different test weights (which relates to payload) and different
towing capacities.  EPA curb weight was determined to be an inadequate
criterion to base the standard on.

CO2 was graphed vs. ALVW, and a more linear relationship was observed in
comparison to the graph using EPA curb weight.  There was still large
variation in CO2, due to the fact of not capturing the capability of the
vehicle completely.  ALVW was determined to be an inadequate criterion
to base the standard on.

CO2 was graphed vs. payload, and the graph was not linear.  A large
variation in CO2 was observed, due to the fact of not capturing the
capability of the vehicle completely.  Payload is not a good criterion
to base the standard on.

CO2 was graphed vs. GCWR, and the graph was linear, but at the same GCWR
vehicles can have very different CO2.  The large variation in CO2 showed
that GCWR does not completely capture the capability of a vehicle.  GCWR
was determined to be an inadequate criterion to base the standard on.

CO2 was graphed vs. GVWR, and the graph was linear, but like GCWR at the
same GVWR, vehicles can have very different CO2.  The large variation in
CO2 indicated that GVWR does not completely capture the capability of a
vehicle.  GVWR was determined to be an inadequate criterion to base the
standard on.

These vehicle attributes individually did not adequately capture the
capability of the heavy duty vehicles.  The EPA also looked at a measure
of capability that is a combination of attributes.  It is called the
“Work Factor” of the vehicle.  The work factor is defined as .75 *
(payload +500 if 4wd) +. 25 * towing.  Work factor gives a very linear
graph with CO2.  There are some outlier vehicles, but overall it was
determined to be the best measure of capability.

How was the Baseline stringency determined?

To determine the baseline level of stringency, a curve was determined
using the baseline CO2 data.  The data was analyzed based on the
criterion (work factor) calculated in the previous section.  It was
necessary to analyze the baseline using a linear line fit given that it
is one of our goals not to eliminate vehicles in this category.  Using a
linear line fit gives equal weighting to each vehicle configuration
ensuring that no vehicle configuration dominated the standard whether it
has high or low CO2 given its work factor.

The linear fit produces the equation:

CO2= 0.0489 * (Work Factor) + 377

Baselines for future standards may be created using production
weighting.  Production weighting will give greatest weight to vehicles
with the largest production.  This is a good method when a fleet’s
demand is well known, but given the uncertainty with the current fleet,
it is best to use a linear line fit. 

How was the Baseline used to determine the Standard?

To determine a standard, CO2 reducing technologies for this segment were
reviewed.  It was determined that different technologies applied to gas
vehicles than to diesel vehicles.  There were more CO2 technologies
available for diesel vehicles than gas vehicles.  This led to two
different percent CO2 reductions, and separate standards for the gas and
diesel vehicles.  A 15 percent reduction is possible for diesel vehicles
given the technology currently on vehicles in the baseline and the CO2
reducing technologies available.  A 10 percent reduction is possible for
gas vehicles given the technology currently on vehicles in the baseline
and the CO2 reduction technologies available. 

Using these percentages, separate standards were determined for gas and
diesel vehicles.

The final standard for gas has the equation:

CO2= 0.0440 * (Work Factor) + 339

The final standard for diesel has the equation:

CO2= 0.0416 * (Work Factor) + 320

 

What is the phase in for the Standard?

The phase in percentages (shown in   REF _Ref271018133 \h  Table 1.3-1
Phase in Percentages ) are the same for both the gasoline and diesel
standard.

Table   STYLEREF 2 \s  1.3 -  SEQ Table \* ARABIC \s 2  1  Phase in
Percentages

Year	Phase-In Percentage

2014	15%

2015	20%

2016	40%

2017	60%

2018	100%

  REF _Ref271025643 \h  Table 1.3-2  Diesel CO2 Standard Equations )
shows how the standard is phased in for diesel vehicles. 

Table   STYLEREF 2 \s  1.3 -  SEQ Table \* ARABIC \s 2  2   Diesel CO2
Standard Equations

Year	Equation

2014	CO2= 0.0478 * (Work Factor) + 368

2015	CO2= 0.0474 * (Work Factor) + 366

2016	CO2= 0.0460 * (Work Factor) + 354

2017	CO2= 0.0445 * (Work Factor) + 343

2018	CO2= 0.0416 * (Work Factor) + 320

  REF _Ref271025884 \h  

Table 1.3-3  Gasoline CO2 Standard Equations ) shows how the standard is
phased in for gasoline vehicles. 

Table   STYLEREF 2 \s  1.3 -  SEQ Table \* ARABIC \s 2  3   Gasoline CO2
Standard Equations

Year	Equation

2014	CO2= 0.0482 * (Work Factor) + 371

2015	CO2= 0.0479 * (Work Factor) + 369

2016	CO2= 0.0469 * (Work Factor) + 362

2017	CO2= 0.0460 * (Work Factor) + 354

2018	CO2= 0.0440 * (Work Factor) + 339

How is the vehicle technology package effectiveness determined?

The individual CO2 reducing technologies are discussed in the Preamble
and Chapter 3 of the draft RIA.  Each technology discussed has a range
of CO2 reduction potential taking into account variations of
implementation for class 2B and 3 vehicles.  As in the 2016 light duty
final rule, the combined CO2 reduction for vehicle technology packages
are determined using the lumped parameter model.  A class 2B and 3
version of the lumped parameter is located in the docket.  

  PAGE  1