ANNEX

Methodology to determine the CO2 savings of exterior vehicle lighting using light emitting diodes (LEDs) for the use in M1 non-externally chargeable hybrid electrified vehicles (NOVC-HEV)

1.   INTRODUCTION

In order to determine the CO2 emission reductions that can be attributed to a package of efficient exterior LED lights consisting of an appropriate combination of vehicle lights referred to in Article 1 for the use in M1 non-externally chargeable hybrid electrified vehicles (NOVC-HEVs), it is necessary to establish the following:

(1)	Testing conditions;

(2)	Test equipment;

(3)	Determination of the power savings;

(4)	Calculation of the CO2 savings;

(5)	Calculation of the statistical error.

2.   SYMBOLS, PARAMETERS AND UNITS

Latin symbols

c	—	Correction factor for the nominal voltage of the High Voltage battery
	—	CO2 savings [g CO2/km]
CO2	—	Carbon dioxide
	—	CO2 correction factor [gCO2/km · Ah], as defined in Regulation UN/ECE No 101, Annex 8
m	—	Number of efficient exterior LED lights composing the package
n	—	Number of measurements of the sample
P	—	Power consumption of the vehicle light [W]
	—	Standard deviation of the LED light power consumption [W]
	—	Standard deviation of the LED light power consumption mean [W]
	—	Standard deviation of the total CO2 savings [g CO2/km]
t	—	Driving duration of the NEDC [s], which is 1 180 s
UF	—	Usage factor of the vehicle light [-] as defined in Table 2
	—	Nominal voltage of the High Voltage battery (traction battery) [V]
	—	Operative voltage of the High Voltage battery (traction battery) [V]
	—	Sensitivity of calculated CO2 savings related to the LED light power consumption
	—	Sensitivity of calculated CO2 savings related to the CO2 correction factor

Greek symbols

ηDCDC

—

Efficiency of the DC-DC converter

Subscripts

Index (i) refers to vehicle lights

Index (j) refers to measurement of the sample

B	—	Baseline
EI	—	Eco-innovative

3.   TESTING CONDITIONS

The testing conditions shall fulfil the requirements of Regulation UN/ECE 112 (1) on Uniform provisions concerning the approval of motor vehicle headlamps emitting an asymmetrical passing beam or a driving beam or both and equipped with filament lamps and/or light-emitting diode (LED) modules. The power consumption shall be determined in accordance with point 6.1.4 of Regulation UN/ECE No 112 and points 3.2.1 and 3.2.2 of Annex 10 to that Regulation.

4.   TEST EQUIPMENT

The following equipment is to be used, as shown in the figure:

—	A power supply unit (i.e. variable voltage supplier);

—	Two Digital Multi Meters, one for measuring the DC-current, and the other for measuring the DC-voltage. In the figure a possible test set-up is shown, when the DC-voltage meter is integrated in the power supply unit.

Test set-up

5.   MEASUREMENTS AND DETERMINATION OF THE POWER SAVINGS

For each efficient exterior LED light included in the package the measurement of the current shall be performed as shown in the figure at a voltage of 13,2 V. LED module(s) operated by an electronic light source control gear, shall be measured as specified by the applicant.

The manufacturer may request that other measurements of the current shall be done at other additional voltages. In that case, the manufacturer must hand over verified documentation on the necessity to perform these other measurements to the type-approval authority. The measurements of the currents at each of those additional voltages are to be performed consecutively at least five (5) times. The exact installed voltages and the measured current is to be recorded in four decimals.

The power consumption has to be determined by multiplying the installed voltage with the measured current. The average of the power consumption for each efficient exterior LED light () has to be calculated. Each value must be expressed in 4 decimals. When a stepper motor or electronic controller is used for the supply of the electricity to the LED lamps, then the electric load of this component part is to be excluded from the measurement.

The resulting power savings of each efficient exterior LED light (ΔPi) are to be calculated with the following formula:

Formula 1

where the power consumption of the corresponding baseline vehicle light is defined by Table 1.

Table 1

Power requirements for different baseline vehicle lights

Vehicle light	Total electric power (PB) [W]
Low beam headlamp	137
High beam headlamp	150
Front position	12
Licence plate	12
Front fog lamp	124
Rear fog lamp	26
Front turn signal lamp	13
Rear turn signal lamp	13
Reversing lamp	52

6.   CALCULATION OF THE CO2 SAVINGS

The total CO2 savings of the lighting package are to be calculated by Formula 2.

Formula 2

where

UF	:	Usage factor of the vehicle light [-] as defined in Table 2.
t	:	Driving duration of the NEDC [s], which is 1 180 s
	:	CO2 correction factor [gCO2/km · Ah], as defined in Regulation UN/ECE No 101, Annex 8
ηDCDC	:	Efficiency of the DC-DC converter [-]
	:	Operative voltage of the High Voltage battery (traction battery) [V], defined by Formula 3

Formula 3

where

	:	Nominal voltage of the High Voltage battery (traction battery) [V]
c	:	Correction factor for the nominal voltage of the High Voltage battery, which is 0,90 for nickel-metal hydride (NiMH) high voltage batteries [-]

The efficiency of the DC-DC converter (ηDCDC) shall be the highest value resulting from the efficiency tests performed in the operative electric current range. The measuring interval shall be equal or lower than 10 % of the operative electric current range.

Table 2

Usage factor for different vehicle lights

Vehicle light	Usage factor (UF) [-]
Low beam headlamp	0,33
High beam headlamp	0,03
Front position	0,36
Licence plate	0,36
Front fog lamp	0,01
Rear fog lamp	0,01
Front turn signal lamp	0,15
Rear turn signal lamp	0,15
Reversing lamp	0,01

7.   CALCULATION OF THE STATISTICAL ERROR

The statistical errors in the outcomes of the testing methodology caused by the measurements are to be quantified. For each efficient exterior LED light included in the package the standard deviation is calculated as defined by Formula 4.

Formula 4

where:

n

:

Number of measurements of the sample, which is at least 5

The CO2-emission correction coefficient shall be determined from a set of T measurements performed by the manufacturer, as defined in Regulation UN/ECE No 101, Annex 8. For each measurement, the electricity balance during the test and the measured CO2-emissions shall be recorded.

In order to evaluate the statistical error of , all T combinations without repetitions of T-1 measurements has to be used to extrapolate T different values of (i.e. ). The extrapolation shall be performed according to the method defined in Regulation UN/ECE No 101, Annex 8.

The standard deviation of is thus calculated as defined by Formula 5.

Formula 5

where:

T	:	Number of measurements performed by the manufacturer for the extrapolation of the as defined in Regulation UN/ECE No 101, Annex 8
	:	mean of the T values of

The standard deviation of the power consumption of each efficient exterior LED light () and the standard deviation of the lead to an error in the CO2 savings (). This error is to be calculated by means of Formula 6.

Formula 6

Statistical significance

It has to be demonstrated for each type, variant and version of a vehicle fitted with the package of the efficient exterior LED lights that the error in the CO2 savings calculated with Formula 6 is not greater than the difference between the total CO2 savings and the minimum savings threshold specified in Article 9(1) of Implementing Regulation (EU) No 725/2011 (see Formula 7).

Formula 7

where:

MT

:

Minimum threshold [gCO2/km], which is 1 gCO2/km

Where the total CO2 emission savings of the package of the efficient exterior LED lights, as a result of the calculation using Formula 2, and the error in the CO2 savings calculated with Formula 6, are below the threshold specified in Article 9(1) of Implementing Regulation (EU) No 725/2011, the second subparagraph of Article 11(2) of that Regulation shall apply.

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(1)  E/ECE/324/Rev.2/Add.111/Rev.3 — E/ECE/TRANS/505/Rev.2/Add.111/Rev.3, 9 January 2013