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Introduction to real-world CO2 emissions and

laboratory testing

Ispra – March 04th, 2016

Meeting with the SAM-HLG

Disclaimer: The views expressed are purely those of the writer and may not in any circumstance be regarded as stating an official position of the European Commission

G. Fontaras, B. Ciuffo, M. Weiss, P.

Bonnel, T. Vlachos and A. Krasenbrink

Institute for Energy and Transport Sustainable Transport Unit

• Brief definition of the problem & key figures

• CO2 from light-duty vehicles: type-approval vs. in-use values

• Current strategy to reduce the gap between type-approval and real-life

CO2: the WLTP

• RDE CO2 & Emissions

• Additional possible approaches

Outline

Consumer choses (also) based

on this

Expects these costs

Expects to consume this much

Thinks that pollutes this much

3

Brief problem definition (1/2)

5.4 3.8 4.4

117g/km

Policy is based on a figure like this …

117gCO2/km or 4.4 l/100km

…as is OEM performance assessment (and potential fines)

Source: ICCT

...systematically different and (lately) increasingly higher But reality can be different…

4

Brief problem definition (2/2)

• 1974: First emissions regulation / test method established

• 1980: Inclusion of CO2 emissions in testing

• 1991: First discussions on CO2 targets

• 1995: the EC proposed ‘120g/km target by 2005’

• 1998: A Voluntary Agreement of ‘140 g/km by 2008’

• 2009: ‘120(130)g/km by 2015’ & prop. ‘95 g/km by 2020’

• 2013: EP accepts 95g/km (2021), and proposes 68–78g/km

(2025)

• 2014: 95g/km (2021) target set by the EU law

Historical background

• All targets are based on CO2 emissions measured during

vehicle type-approval (type I test or NEDC test)

Vehicle type-approval system in Europe

NEDC

• The average emissions of the pass. cars registered in the EU

in 2015 shall not average more than 130 gCO2/km

(~5.2l/100km)

Target

achieved

Present situation - EU

• Since monitoring started in 2010, emissions have decreased

by 17 g CO2/km (12 %).

• Progresses are in line with the requirements of 2020 targets

Source EEA

Present situation - EU

The actual situation might not be so straightforward and

optimistic

• Official and experienced FC

values don’t always match

• Numerous discussions by

ordinary or professional drivers

on the topic

• Concerns by various NGOs

• JRC estimates real world FC &

CO2 to be on average 25-30%

(2013 data) higher than officially

reported (research on-going)

Source: JRC internal analysis

Reality might tell something different

• “Gap” issue already identified in 2005

• 2005 Estimates in the order of ~10-15%

• Not only a European issue

• Several researchers* attempt quantifications

based on various approaches (emissions inventories, vehicle

simulations, fuel sales based estimations etc)

Common: in Europe the divergence of the real vs certified

CO2 / Fuel consumption has widened in the past 10 years

and is further widening with time

* Van den Brink and Van Wee 2001, ECMT 2005, Fontaras et al. 2007, Meyer and Wessely 2009, Zallilnger and Hausberger

2009, Dings 2010, Keller et al. 2011, Kadijk et al. 2012, Fontaras and Dilara 2012, Dings 2013, Ligterink and Eijik 2014,

Mock et al. 2014, Ntziachristos et al. 2014

Widening of the “gap”

Source: ICCT 2014

Introduction of binding targets Each g of CO2 in excess can potentially cost up to 95E per vehicle sold

2008-2010 a trend changing period

• Laboratory tests for Automaker compliance with standards

• Adjusted values for consumer information and CO2 monitoring

• * http://www3.epa.gov/fueleconomy/fetrends/1975-2015/420r15016.pdf

US situation

Unadjusted ~31.3mpg Adjusted ~25.1mpg

Potential gap: 1.83l/100km or 20% (9.37l - 7.54) l/100 US: About 42g CO2 /km EU: About 37g CO2/km (assuming average of 125g CO2/km and 30% gap)

Difference in CO2 & FC

Origin Test

Test definition & boundaries (fixed temperature, driving cycle, no

auxiliaries)

Test elasticities (eg fully charged battery, optimal

tyres, no side mirrors etc)

Malevolent acts? (eg VW case)

Origin “Reality”

Vehicle (eg different mass, tyres, auxiliaries, maintenance)

Driver (eg aggressive, calm, habits )

Environment (eg weather, traffic, road

morphology)

Origins of the “gap”

Origins of the “gap”

Difference in CO2 & FC

Origin “Reality”

Vehicle (eg different mass, tyres, auxiliaries, maintenance)

Driver (eg aggressive, calm, habits )

Environment (eg weather, traffic, road

morphology)

WLTP covers some aspects (more realistic) Which reality? It is a personal, environmental & time relevant issue –who drives what, how and where? Cannot define “one” all-purpose fuel consumption value

15

Category Factor

Literature

average

value

Sources

No.

-15.

0%

-5.0

%

0.0%

2.5%

5.0%

7.5%

10.0

%

12.5

%

15.0

%

20.0

%

25.0

%

35.0

%

45.0

%

55.0

%

65.0

%

Increased electrical supply is required 5.0% 10

Improved MAC systems, EV HVAC - heat pump, active seat

ventilation, solar reflective paint, solar control glazing, solar roofs-1.7% 8

Steering assist systemsHydraulic Power Assisted Steering, Electro - Hydraylic Power Assisted

Steering, Electric Power Assisted Steering. Improved steering pump3.2% 3

Other vehicle auxiliariesEngine management, fuel injection, fog lamps, brake lights, wipers,

dipped beams, brake assist, heated windscreen, fan, etc5.5% 6

Roof add - ons and

modificationsVarious add - ons that are attached to the roof, except for a roof box 3.6% 2

Roof racks / boxes (air drag

increase)

Effect on fuel consumption with the addition of an un - laden roof

box. Increased aerodynamic resistance4.5% 5

Open windows At a speed of 130 km/h, based mainly on an american study 4.8% 3

Sidewinds effect

Change in aerodynamic drag and frontal area, depends on wind

velocity and angle. Results for 10% air drag increase (caused from 15o

to 30o yaw angle or from 4 - 8 m/s wind velocity)

2.0% 5

Improvements Spoilers, vortex generators -0.4% 3

RainWheels have to push through water. Increase for 1 mm of water

depth on road surface80.0%

Snow/IceDecreased tire grip, wasting energy. Lower than normal driving

speeds. Decreased tire pressure

Qualitative

data

0 oC compared to 20 oC 10.0%

-20 oC compared to 0 oC 10.0%

Aggressive driving High acceleration and deceleration, braking and maximum speed 26.0% 10

Driving modeConsumption varies according to Eco or Sport mode. Non scientific

research claims increase up to 11% for Sport mode

Qualitative

data6

Eco - driving

Optimal gear shifting, smooth accelerations and decelerations, steady

speed maintenance, anticipation of movement and traffic, Green -

Light Optimal Speed Advisory (GLOSA)

-6.5% 6

Lubrication Use of low viscosity motor oil results in lower internal friction -2.4% 13

Low resistance tires by 10 - 20% -3.0%

Lower tire pressure by 0.2 bar 1.0%

Other Clogged air filters, misaligned wheels, poorly tuned engine 3.5% 5

Vehicle mass Increased mass by 100 kg 5.8% 17

Trailer towing Affects weight, rolling resistance, aerodynamics and driving behavior 58.4% 3

Roof racks / boxes (mass

increase)Fuel consumption increases as speed increases 19.7% 5

Altitude increase decreases consumption, as air density, aerodynamic

resistance and oxygen concetration decrease-3.8% 3

Road grade increases fuel consumption as the car is driven uphill.

Results based on American studies for a car driven on a hilly route13.3% 3

Road surface Affected by roughness, surface texture and uneveness 2.7% 4

Traffic condition Reduced speed, increased idle time and start and stops at congestion 30.0% 3

Trip typeShort trips. More cold starts and cold start emissions. Engine normal

operation temperature not reached10.0% 3

B10 fuel blend compared to B0 1.0% 2

E10 fuel blend compared to E0 3.8% 3Fuel characteristics Difference in fuel properties

Auxiliary systems

Air conditioning

Operational mass

Aerodynamics

Temperature, the type

approval test current range

is 20 - 29 oC

Vehicle condition Tires

Road conditions

Driving behaviour/style

Distribution

15

19

Road morphology

Weather conditions

3

-15% -10% -5% 0% 5% 10% 15% 20% 25% 30% 35% 40% 45%

Origins of the “gap”

Difference in CO2 & FC

Origin Test

Test definition & boundaries (fixed temperature, driving cycle, no

auxiliaries)

Test elasticities (eg fully charged battery, optimal

tyres, no side mirrors etc)

Malevolent acts? (eg VW case)

Most to be addressed by WLTP*: • Test definitions more

realistic (eg continuous mass) • Known elasticities eliminated

*New test procedure

• Never considered prior to VW-gate

• TA approval scheme founded on mutual trust and quality control No official post-test validation

• RDE could potentially help if…

• Conscious of the limitations of the NEDC, already in the EC Regulation

443/2009 and 510/2011 (setting the CO2 targets for PC and LCV) the

Commission set the political objective to implement a new and more

realistic test cycle by 2014

• In June 2009, in fact, at the UNECE level a road map for the

development of a new test procedure had already been presented. The

work for the development of the Worldwide harmonized Light vehicles

Test Procedures (WLTP) had already started

• The objective was to design

• a more realistic test-cycle

• a more stringent test procedure (less prone than the NEDC to

interpretations and flexibilities)

Current EC strategy to reduce the “gap”

Key Parameters of the Driving Cycles NEDC and WLTC

Parameters NEDC WLTP

duration (s) 1180 1800

distance (km) 11.03 23.27

av. speed (km/h) 33.6 46.5

maximum speed (km/h) 120 131.3

stop duration (%) 23.7 12.6

constant driving (%) 40.3 3.7

acceleration (%) 20.9 43.8

deceleration (%) 15.1 39.9

av. positive acc. (m/s2) 0.59 0.41

max positive acc. (m/s2) 1.04 1.67

av. positive “speed*acc.” (m2/s3) 1.04 1.99

max positive “speed*acc.” (m2/s3) 9.22 21.01

av. deceleration (m/s2) −0.82 −0.45

minimum deceleration (m/s2) −1.39 −1.50

Old Cycle (NEDC) vs New Cycle (WLTC)

Category Item inNEDC inWLTP ImpactonCO2

Vehicletestmass Present Modified é

Tireselection Present Modified é

Tirepressure Present Modified é

Tiretreaddepth Present Modified é

Calculationofresistanceforces Present Corrected é

Inertiaofrotatingparts Absent Introduced é

Deafaultroadloadcoefficients Present Modified ?

Drivingcycle Present Modified ±

Testtemperarure Present Modified é

Vehicleinertia Present Modified é

Preconditioning Present Modified é

GearShiftstrategy Present Modifiedê

SOCcorrection Absent Introduced é

Correctionofcycleflexibilities Absent Underdiscussion ±

CoC

CO2type-approvalextension/vehiclefamily Present Modified é

Road

Load

Determ

ination

Laboratorytest

Processing

testresults

Old Test (NEDC) vs New Test (WLTP)

WLTP phasing-in (2017-2020)

• Existing targets are NEDC Based

• Industry needs a minimum lead in time of 5 years to adapt

• WLTP-based CO2 emissions (measured at type-approval) will be translated in the

equivalent NEDC-based ones and then used in to assess the compliance towards

CO2 emission targets

CO2MPAS Technology modeling

Power-RPM

model

GB/GS model

Fuel consumption

model

WLTP test-results

Vehicle data (Mass, RL,

Transmission,…)

NEDC-equivalent CO2

emissions

EU Fleet CO2 Emissions Simulation Results for NEDC & WLTP

y=0.8874x+26.119

50

100

150

200

250

300

50 100 150 200 250 300

WLTPCO2emissions(g/km)

NEDCCO2emissions(g/km)

Rela onshipbetweenNEDCandWLTPCO2emissions

CO2(g/km) TrendLine y=x

* Pivoted WLTP results are calculated applying the ratio between NEDC simulated emissions and the reported ones, to the WLTP simulated CO2 emissions.

From NEDC to WLTP to Reality

Source: JRC internal analysis

CO2 & RDE

RDE

• Analyzer unit (NOx, CO, CO2, HC, PN) in the cabin or

on a tow bar

• Tail-pipe connection of exhaust flow meter

• Electrical batteries in the cabin

• Weather station and GPS on/near the roof

• Connection to the engine control unit possible

• Total PEMS mass: first generation ≈100-130 kg;

second generation ≈60 kg (+ 1 co-pilot)

CO2 emissions in the laboratory and on the road (complete routes)

• 6 cars (4 diesel, 2 gasoline; 4 Euro 6, 2 Euro 5)

TypeApproval(NEDC)

NEDCmeasured

WLTCcorrected

WLTCmeasured

RDE (Alltrips)

RDE (MAWvalid trips)

Cycles/NEDC 1.0 1.1 1.4 1.1 1.3 1.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

CO

2e

mis

sio

ns

vari

atio

n [

-]

Diff 1.2-1.3 in- line with estimates

RDE CO2 data - strengths and limitations

• Strength

• CO2 data recorded from actual on-road driving

• RDE tests of up to 2h generate a large data pool

• Potential coverage of a wide range of conditions

• Detection of emission anomalies

• Robustness against defeat strategies

• Limitations

• Potentially biased trip design deviating from average driving

• Biases in trip duration, driving conditions, vehicle load

• Driving referenced to WLTP conditions

• Low repeatability of CO2 measurements

• Measurement uncertainty higher than under laboratory conditions

Summary

Is the “gap” a problem?

• From the analyses carried out:

• With WLTP the gap will reduce with respect to the NEDC case

• A “gap” with the average in-use CO2 is likely to remain

• A “gap” seems unavoidable due to the very nature of the laboratory

tests if compared to the variability of the real-life conditions

• But is the “gap” a problem?

• From a consumer perspective, the “gap” is a problem if it is

different for different vehicles so that it can mislead the purchasing

choices. Otherwise it is almost irrelevant

• From the regulatory perspective, the “gap” is a problem if it widens

over time, so that the progresses made in reducing the CO2

emissions are mostly visible in the lab than on the road. Otherwise

the gap is totally irrelevant

Is WLTP sufficient to take the “gap” under control?

• The WLTP represents a considerable step forward in addressing the

problem. Whether it will suffice alone or additional measures are

necessary is difficult to be assessed before its actual introduction

• A mechanism to monitor the evolution of this gap can be considered

by the EC. Potential options:

• Compare WLTP-CO2 and the CO2 after a RDE test and check whether the

average difference tends to vary for a certain manufacturer

• Use CO2MPAS calibrated with the results of a RDE test to verify and/or

adjust the type-approval value

• Record and monitor cumulative fuel consumption in vehicles’ OBD after

any mandatory service and check that the average difference with the

WLTP values per each manufacturer does not increase

Could RDE be the way forward?

• RDE provides some first-order estimate of real-world CO2 emissions

• RDE for market surveillance and as low-cost verification procedure

• Adaptations needed to use RDE as CO2 certification procedure

• Elements of RDE test procedure can be used to design on-road CO2

emissions test

• Data pool from RDE tests can be used

• Use of fuel consumption meters instead of PEMS (improves

measurement)

• From the data pool RDE events could be selected to re-construct

desired average driving pattern (e.g., WLTC) and CO2 emissions

• Data source for CO2 modelling

Is a TA-based target enough?

• Real savings are achieved in real-life. What can the EC do?

Vehicles are already heavily regulated, avoid additional measures during

the transition period to WLTP – exploit existing tools to the best extent

Help “upgrade” fuel consumption to purchase criterion n. 2 after safety

Open to the public: drivers are not dumb. They should have access to more

info regarding their cars

Provide on-line tools & apps that can educate drivers and promote

behaviors and CO2 saving technologies

Draft best practices guidelines and information packages for the drivers

Educate the public make data sources available !

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