Appendix 1

United Kingdom

Test procedure for vehicle emissions testing with portable emissions measurement systems

INTRODUCTION

This Appendix describes the procedure to determine gaseous emissions from on-vehicle on-road measurements using Portable Emissions Measurement Systems (hereinafter ‘PEMS’). The pollutant emissions to be measured from the exhaust of the engine include the following components: carbon monoxide, total hydrocarbons and nitrogen oxides for compression ignition engines and carbon monoxide, non-methane hydrocarbons, methane and nitrogen oxides for positive ignition engines. Additionally, carbon dioxide shall be measured to enable the calculation procedures described in Section 4.

For engines fuelled with natural gas, the manufacturer, technical service or approval authority may choose to measure the total hydrocarbon (THC) emissions only instead of measuring the methane and non-methane hydrocarbon emissions. In that case, the emission limit for the total hydrocarbon emissions is the same as the one specified in Annex I to Regulation (EC) No 595/2009 for methane emissions. For the purposes of the calculation of the conformity factors pursuant to points 4.2.3 and 4.3.2 of this Appendix, the applicable limit shall be the methane emission limit only.

For engines fuelled with gases other than natural gas, the manufacturer, technical service or approval authority may choose to measure the total hydrocarbon (THC) emissions instead of measuring the non-methane hydrocarbon emissions. In that case, the emission limit for the total hydrocarbon emissions is the same as the one specified in Annex I to Regulation (EC) No 595/2009 for non-methane hydrocarbon emissions. For the purposes of the calculation of the Conformity Factors pursuant to points 4.2.3 and 4.3.2 of this Appendix, the applicable limit shall be the non-methane emission limit.

TEST PROCEDURE

2.1.

General requirements

The tests shall be carried out with a PEMS comprised of:

2.1.1.
Gas analysers to measure the concentrations of regulated gaseous pollutants in the exhaust gas.
2.1.2.
An exhaust mass flow meter based on the averaging Pitot or equivalent principle.
2.1.3.
A Global Positioning System (hereinafter ‘GPS’).
2.1.4.
Sensors to measure the ambient temperature and pressure.
2.1.5.
A connection with the vehicle ECU).

2.2.

Test parameters

F2The parameters as specified in Table 1 shall be measured and recorded at a constant frequency of 1,0 Hz or higher. The original raw data shall be kept by the manufacturer and shall be made available, upon request, to the approval authority F3...:

Table 1

Test parameters

Parameter	Unit	Source
Measured or corrected to a wet basis.
Gas engines only.
Use the ambient temperature sensor or an intake air temperature sensor.
F4The recorded value shall be either (a) the net brake engine torque in accordance with point 2.4.4 of this Appendix or (b) the net brake engine torque calculated from the torque values in accordance with point 2.4.4 of this Appendix.
THC concentration^f1	ppm	Analyser
CO concentration	ppm	Analyser
NO_x concentration	ppm	Analyser
CO₂ concentration	ppm	Analyser
CH₄ concentration^f2	ppm	Analyser
Exhaust gas flow	kg/h	Exhaust Flow Meter (hereinafter ‘EFM’)
Exhaust temperature	°K	EFM
Ambient temperature^f3	°K	Sensor
Ambient pressure	kPa	Sensor
Engine torque^f4	Nm	ECU or Sensor
Engine speed	rpm	ECU or Sensor
Engine fuel flow	g/s	ECU or Sensor
Engine coolant temperature	°K	ECU or Sensor
Engine intake air temperature	°K	Sensor
Vehicle ground speed	km/h	ECU and GPS
Vehicle latitude	degree	GPS
Vehicle longitude	degree	GPS

F52.2.1.

Data reporting format

Emission values as well as any other relevant parameters shall be reported and exchanged as csv-formatted data file. Parameter values shall be separated by a comma, ASCII-Code #h2C. The decimal marker of numerical values shall be a point, ASCII-Code #h2E. Lines shall be terminated by carriage return, ASCII-Code #h0D. No thousands separators shall be used.

2.3.

Preparation of the vehicle

The preparation of the vehicle shall include the following:

(a)
the check of the OBD system: any identified problems once solved shall be recorded and presented to the approval authority;
(b)
the replacement of oil, fuel and reagent, if any.

2.4.

Installation of the measuring equipment

2.4.1.

Main Unit

Whenever possible, PEMS shall be installed in a location where it will be subject to minimal impact from the following:

(a)
ambient temperature changes;
(b)
ambient pressure changes;
(c)
electromagnetic radiation;
(d)
mechanical shock and vibration;
(e)
ambient hydrocarbons — if using a FID analyser that uses ambient air as FID burner air.

The installation shall follow the instructions issued by the PEMS manufacturer.

2.4.2.

Exhaust flow meter

The exhaust flow meter shall be attached to the vehicle’s tailpipe. The EFM sensors shall be placed between two pieces of straight tube whose length should be at least 2 times the EFM diameter (upstream and downstream). It is recommended to place the EFM after the vehicle silencer, to limit the effect of exhaust gas pulsations upon the measurement signals.

2.4.3.

Global Positioning System

The antenna shall be mounted at the highest possible location, without risking interference with any obstructions encountered during on-road operation.

2.4.4.

Connection with the vehicle ECU

A data logger shall be used to record the engine parameters listed in Table 1. This data logger can make use of the Control Area Network (CAN) bus of the vehicle to access the ECU data specified in Table 1 of Appendix 5 of Annex 9B to UNECE Regulation No 49 and broadcasted on the CAN according to standard protocols, such as SAE J1939, J1708 or ISO 15765-4. It may calculate the net brake engine torque or perform unit conversions.

2.4.5.

Sampling of gaseous emissions

The sample line shall be heated according to the specifications of point 2.3 of Appendix 2 and properly insulated at the connection points (sample probe and back of the main unit), to avoid the presence of cold spots that could lead to a contamination of the sampling system by condensed hydrocarbons.

The sample probe shall be installed in the exhaust pipe in accordance with the requirements set out in paragraph 9.3.10 of Annex 4 to UNECE Regulation No 49.

If the length of the sample line is changed, the system transport times shall be verified and if necessary corrected.

2.5.

Pre-test procedures

2.5.1.

Starting and stabilising the PEMS instruments

The main units shall be warmed up and stabilised according to the instrument manufacturer specifications until pressures, temperatures and flows have reached their operating set points.

2.5.2.

Cleaning the sampling system

To prevent system contamination, the sampling lines of the PEMS instruments shall be purged until sampling begins, according to the instrument manufacturer specifications.

2.5.3.

Checking and calibrating the analysers

The zero and span calibration and the linearity checks of the analysers shall be performed using calibration gases meeting the requirements set out in paragraph 9.3.3 of Annex 4 to UNECE Regulation No 49. A linearity check shall have been performed within three months before the actual test.

2.5.4.

Cleaning the EFM

The EFM shall be purged at the pressure transducer connections in accordance with the instrument manufacturer specifications. This procedure shall remove condensation and diesel particulate matter from the pressure lines and the associated flow tube pressure measurement ports.

2.6.

Emissions test run

2.6.1.

Test start

Emissions sampling, measurement of the exhaust parameters and recording of the engine and ambient data shall commence prior to starting the engine. The coolant temperature shall not exceed 303 K (30 °C) at the beginning of the test. In case ambient temperature exceeds 303 K (30 °C) at the beginning of the test, the coolant temperature shall not exceed the ambient temperature by more than 2 °C. The data evaluation shall start after the coolant temperature has reached 343 K (70 °C) for the first time or after the coolant temperature is stabilised within +/– 2 K over a period of 5 minutes whichever comes first but no later than 15 minutes after engine start.

2.6.2.

Test run

Emission sampling, measurement of the exhaust parameters and recording of the engine and ambient data shall continue throughout the normal in-use operation of the engine. The engine may be stopped and started, but emissions sampling shall continue throughout the entire test.

Periodic zero-checks of the PEMS gas analysers may be conducted every 2 hours and the results may be used to perform a zero drift correction. The data recorded during the checks shall be flagged and shall not be used for the emission calculations.

In case of interrupted GPS signal the GPS data may be calculated based on the ECU vehicle speed and a map, for a consecutive period of less than 60 s. If the cumulative loss of GPS signal exceeds 3 % of the total trip duration, the trip should be declared void.

2.6.3.

End of test sequence

At the end of the test, sufficient time shall be given to the sampling systems to allow their response times to elapse. The engine may be shut down before or after sampling is stopped.

2.7.

Verification of the measurements

2.7.1.

Checking of the analysers

The zero, span and linearity checks of the analysers as described in point 2.5.3. shall be performed using calibration gases meeting the requirements set out in paragraph 9.3.3 of Annex 4 to UNECE Regulation No 49.

2.7.2.

Zero drift

Zero response is defined as the mean response, including noise, to a zero gas during a time interval of at least 30 seconds. The drift of the zero response shall be less than 2 % of full scale on the lowest range used.

2.7.3.

Span drift

Span response is defined as the mean response, including noise, to a span gas during a time interval of at least 30 seconds. The drift of the span response shall be less than 2 % of full scale on the lowest range used.

2.7.4.

Drift verification

This shall apply only if, during the test, no zero drift correction was made.

As soon as practical but no later than 30 minutes after the test is complete the gaseous analyser ranges used shall be zeroed and spanned to check their drift compared to the pre-test results.

The following provisions shall apply for analyser drift:

(a)
if the difference between the pre-test and post-test results is less than 2 % as specified in points 2.7.2 and 2.7.3, the measured concentrations may be used uncorrected or may be corrected for drift according to point 2.7.5;
(b)
if the difference between the pre-test and post-test results is equal to or greater than 2 % as specified in points 2.7.2 and 2.7.3, the test shall be voided or the measured concentrations shall be corrected for drift according to point 2.7.5.

2.7.5.

Drift correction

If drift correction is applied in accordance with point 2.7.4, the corrected concentration value shall be calculated in accordance with paragraph 8.6.1 of Annex 4 to UNECE Regulation No 49.

The difference between the uncorrected and the corrected brake-specific emission values shall be within ± 6 % of the uncorrected brake-specific emission values. If the drift is greater than 6 %, the test shall be voided. If drift correction is applied, only the drift-corrected emission results shall be used when reporting emissions.

CALCULATION OF THE EMISSIONS

The final test result shall be rounded in one step to the number of places to the right of the decimal point indicated by the applicable emission standard plus one additional significant figure, in accordance with ASTM E 29-06b. No rounding of intermediate values leading to the final brake-specific emission result shall be allowed.

3.1.

Time alignment of data

To minimise the biasing effect of the time lag between the different signals on the calculation of mass emissions, the data relevant for emissions calculation shall be time aligned, as described in points 3.1.1 to 3.1.4.

3.1.1.

Gas analysers data

The data from the gas analysers shall be properly aligned using the procedure laid down in paragraph 9.3.5 of Annex 4 to UNECE Regulation No 49.

3.1.2.

Gas analysers and EFM data

The data from the gas analysers shall be properly aligned with the data of the EFM using the procedure in point 3.1.4.

3.1.3.

PEMS and engine data

The data from the PEMS (gas analysers and EFM) shall be properly aligned with the data from the engine ECU using the procedure in point 3.1.4.

3.1.4.

Procedure for improved time-alignment of the PEMS data

The test data listed in Table 1 are split into 3 different categories:

Gas analysers (THC, CO, CO₂, NO_x concentrations);

Exhaust Flow Meter (Exhaust mass flow and exhaust temperature);

Engine (Torque, speed, temperatures, fuel rate, vehicle speed from ECU).

The time alignment of each category with the other categories shall be verified by finding the highest correlation coefficient between two series of parameters. All the parameters in a category shall be shifted to maximise the correlation factor. The following parameters shall be used to calculate the correlation coefficients:

To time-align:

(a)
categories 1 and 2 (Analysers and EFM data) with category 3 (Engine data): the vehicle speed from the GPS and from the ECU;
(b)
category 1 with category 2: the CO₂ concentration and the exhaust mass;
(c)
category 2 with category 3: the CO₂ concentration and the engine fuel flow.

3.2.

Data consistency checks

3.2.1.

Analysers and EFM data

The consistency of the data (exhaust mass flow measured by the EFM and gas concentrations) shall be verified using a correlation between the measured fuel flow from the ECU and the fuel flow calculated using the formula in paragraph 8.4.1.7 of Annex 4 to UN/ECE Regulation No 49. A linear regression shall be performed for the measured and calculated fuel rate values. The method of least squares shall be used with the best fit equation having the form:

y = mx + b

where:

— y

is the calculated fuel flow [g/s]

— m

is the slope of the regression line

— x

is the measured fuel flow [g/s]

— b

is the y intercept of the regression line

The slope (m) and the coefficient of determination (r²) shall be calculated for each regression line. It is recommended to perform this analysis in the range from 15 % of the maximum value to the maximum value and at a frequency greater or equal to 1 Hz. For a test to be considered valid, the following two criteria shall be evaluated:

Table 2

Tolerances

Slope of the regression line, m	0,9 to 1,1 — Recommended
Coefficient of determination r ²	min. 0,90 — Mandatory

3.2.2.

ECU torque data

The consistency of the ECU torque data shall be verified by comparing the maximum ECU torque values at different engine speeds with the corresponding values on the official engine full load torque curve according to Section 5 of Annex II.

3.2.3.

Brake-Specific Fuel Consumption

The Brake Specific Fuel Consumption (BSFC) shall be checked using:

(a)
the fuel consumption calculated from the emissions data (gas analyser concentrations and exhaust mass flow data), in accordance with the formula provided for in point 8.4.1.6 of Annex 4 to UNECE Regulation No 49;
(b)
the work calculated using the data from the ECU (Engine torque and engine speed).

3.2.4.

Odometer

The distance indicated by the vehicle odometer shall be checked against the GPS data and verified.

3.2.5.

Ambient pressure

The ambient pressure value shall be checked against the altitude indicated by the GPS data.

3.3.

Dry-Wet correction

If the concentration is measured on a dry basis, it shall be converted to a wet basis in accordance with the formula provided for in paragraph 8.1. of Annex 4 to UNECE Regulation No 49.

3.4.

NO_x correction for humidity and temperature

The NO_x concentrations measured by the PEMS shall not be corrected for ambient air temperature and humidity.

3.5.

Calculation of the instantaneous gaseous emissions

The mass emissions shall be determined as described in paragraph 8.4.2.3 of Annex 4 to UNECE Regulation No 49.

DETERMINATION OF EMISSIONS AND CONFORMITY FACTORS

4.1.

Averaging window principle

The emissions shall be integrated using a moving averaging window method, based on the reference CO₂ mass or the reference work. The principle of the calculation is as follows: The mass emissions are not calculated for the complete data set, but for sub-sets of the complete data set, the length of these sub-sets being determined so as to match the engine CO₂ mass or work measured over the reference laboratory transient cycle. The moving average calculations are conducted with a time increment Δt equal to the data sampling period. These sub-sets used to average the emissions data are referred to as ‘averaging windows’ in the following points.

Any invalidated data shall not be considered for the calculation of the work or CO₂ mass and the emissions of the averaging window.

The following data shall be considered as not valid data:

(a)
zero drift check of the instruments;
(b)
the data outside the conditions specified in points 4.2 and 4.3 of Annex II.

The mass emissions (mg/window) shall be determined as described in paragraph 8.4.2.3 of Annex 4 to UN/ECE Regulation No 49.

Figure 1

Vehicle speed versus time and vehicle averaged emissions, starting from the first averaging window, versus time

4.2.

Work based method

The duration (t_2,i – t_1,i) of the i^th averaging window is determined by:

W (t_{2,i}) - W (t_{1,i}) \geq W_{ref}

where:

W(t_j,i) is the engine work measured between the start and time t_j,i, kWh;
W_ref is the engine work for the WHTC, kWh;
t_2,i shall be selected such that:
$W (t_{2,i} - Δt) - W (t_{1,i}) < W_{ref} \leq W (t_{2,i}) - W (t_{1,i})$

Where Δt is the data sampling period, equal to 1 second or less.

4.2.1.

Calculation of the specific emissions

The specific emissions e_gas (mg/kWh) shall be calculated for each window and each pollutant in the following way:

e_{gas} = \frac{m}{W (t_{2,i}) - W (t_{1,i})}

where:

m is the mass emission of the component, mg/window
W(t_2,i) – W(t_1,i) is the engine work during the i^th averaging window, kWh

F64.2.1.1.

Calculation of the specific emissions for a declared market fuel

If a test pursuant to this Annex was performed with a market fuel declared in point 3.2.2.2.1 of Part 1 in Appendix 4 to Annex I, the specific emissions e_gas (mg/kWh) shall be calculated for each window and each pollutant by multiplication of the uncorrected specific emissions with the power correction factor determined pursuant to point 1.1.2 (a1) of Annex I.

4.2.2.

Selection of valid windows

4.2.2.1.

Before the dates referred to in Article 17a, points 4.2.2.1.1 to 4.2.2.1.4 shall apply.

4.2.2.1.1.

The valid windows are the windows whose average power exceeds the power threshold of 20 % of the maximum engine power. The percentage of valid windows shall be equal or greater than 50 %.

4.2.2.1.2.

If the percentage of valid windows is less than 50 %, the data evaluation shall be repeated using lower power thresholds. The power threshold shall be reduced in steps of 1 % until the percentage of valid windows is equal to or greater than 50 %.

4.2.2.1.3.

In any case, the lower threshold shall not be lower than 15 %.

4.2.2.1.4.

The test shall be void if the percentage of valid windows is less than 50 % at a power threshold of 15 %.

4.2.2.2.

From the dates referred to in Article 17a, points 4.2.2.2.1 and 4.2.2.2.2 shall apply.

4.2.2.2.1.

The valid windows are the windows whose average power exceeds the power threshold of 10 % of the maximum engine power.

F74.2.2.2.2.

The test shall be void if the percentage of valid windows is less than 50 % or if there are no valid windows in respect of nitrogen oxides (NO_x) left in urban only operations after the 90 percentile rule has been applied.

4.2.3.

Calculation of the conformity factors

The conformity factors shall be calculated for each individual valid window and each individual pollutant in the following way:

CF = \frac{e}{L}

where:

e is the brake-specific emission of the component, mg/kWh;
L is the applicable limit, mg/kWh.

4.3.

CO₂ mass based method

The duration (t_2,i – t_1,i) of the i^th averaging window is determined by:

m_{CO2} (t_{2,i}) - m_{CO2} (t_{1,i}) \geq m_{CO2,ref}

where:

m_CO2(t_j,i) is the CO₂ mass measured between the test start and time t_j,i, kg;
m_CO2,ref is the CO₂ mass determined for the WHTC, kg;
t_2,i shall be selected such as:
$m_{CO2} (t_{2,i} - Δt) - m_{CO2} (t_{1,i}) < m_{CO2,ref} \leq m_{CO2} (t_{2,i}) - m_{CO2} (t_{1,i})$

Where Δt is the data sampling period, equal to 1 second or less.

The CO₂ masses are calculated in the windows by integrating the instantaneous emissions calculated according to the requirements introduced in point 3.5.

4.3.1.

Selection of valid windows

4.3.1.1.

Before the dates referred to in Article 17a, points 4.3.1.1.1 to 4.3.1.1.4 shall apply.

4.3.1.1.1.

The valid windows shall be the windows whose duration does not exceed the maximum duration calculated from:

$D_{\max} = 3600 \times \frac{W_{ref}}{0,2 \times P_{\max}}$

where:

D max is the maximum window duration, s,
P max is the maximum engine power, kW.

4.3.1.1.2.

If the percentage of valid windows is less than 50 %, the data evaluation shall be repeated using longer window durations. This is achieved by decreasing the value of 0,2 in the formula given in point 4.3.1 by steps of 0,01 until the percentage of valid windows is equal to or greater than 50 %.

4.3.1.1.3.

In any case, the lowered value in above formula shall not be lower than 0,15.

4.3.1.1.4.

The test shall be void if the percentage of valid windows is less than 50 % at a maximum window duration calculated in accordance with points 4.3.1.1, 4.3.1.1.2 and 4.3.1.1.3.

4.3.1.2.

From the dates referred to in Article 17a, points 4.3.1.2.1 and 4.3.1.2.2 shall apply.

4.3.1.2.1.

The valid windows shall be the windows whose duration does not exceed the maximum duration calculated from:

$D_{\max} = 3600 \times \frac{W_{ref}}{0,1 \times P_{\max}}$

where:

D max is the maximum window duration, s,
P max is the maximum engine power, kW.

4.3.1.2.2.

The test shall be void if the percentage of valid windows is less than 50 %.

4.3.2.

Calculation of the conformity factors

The conformity factors shall be calculated for each individual window and each individual pollutant in the following way:

CF = \frac{{CF}_{I}}{{CF}_{C}}

with ${CF}_{I} = \frac{m}{m_{CO2} (t_{2,i}) - m_{CO2} (t_{1,i})}$ (in service ratio) and

${CF}_{C} = \frac{m_{L}}{m_{CO2,ref}}$ (certification ratio)

where:

m is the mass emission of the component, mg/window;
m_CO2(t_2,i) – m_CO2(t_1,i) is the CO₂ mass during the i^th averaging window, kg;
m_CO2,ref is the engine CO₂ mass determined for the WHTC, kg;
m_L is the mass emission of the component corresponding to the applicable limit on the WHTC, mg.

Annotations

Textual amendments

F1: Substituted by Commission Regulation (EU) 2017/1347 of 13 July 2017 correcting Directive 2007/46/EC of the European Parliament and of the Council, Commission Regulation (EU) No 582/2011 and Commission Regulation (EU) 2017/1151 supplementing Regulation (EC) No 715/2007 of the European Parliament and of the Council on type-approval of motor vehicles with respect to emissions from light passenger and commercial vehicles (Euro 5 and Euro 6) and on access to vehicle repair and maintenance information, amending Directive 2007/46/EC of the European Parliament and of the Council, Commission Regulation (EC) No 692/2008 and Commission Regulation (EU) No 1230/2012 and repealing Regulation (EC) No 692/2008 (Text with EEA relevance).
F2: Substituted by Commission Regulation (EU) 2016/1718 of 20 September 2016 amending Regulation (EU) No 582/2011 with respect to emissions from heavy-duty vehicles as regards the provisions on testing by means of portable emission measurement systems (PEMS) and the procedure for the testing of the durability of replacement pollution control devices (Text with EEA relevance).
F3: Words in Annex 2 Appendix 1 point 2.2 omitted (31.12.2022 at 11.00 p.m.) by virtue of The Road Vehicles and Non-Road Mobile Machinery (Type-Approval) (Amendment and Transitional Provisions) (EU Exit) Regulations 2022 (S.I. 2022/1273), regs. 1(2), 66(10)(e)
F4: Substituted by Commission Regulation (EU) No 133/2014 of 31 January 2014 amending, for the purposes of adapting to technical progress as regards emission limits, Directive 2007/46/EC of the European Parliament and of the Council, Regulation (EC) No 595/2009 of the European Parliament and of the Council and Commission Regulation (EU) No 582/2011 (Text with EEA relevance).
F5: Inserted by Commission Regulation (EU) 2016/1718 of 20 September 2016 amending Regulation (EU) No 582/2011 with respect to emissions from heavy-duty vehicles as regards the provisions on testing by means of portable emission measurement systems (PEMS) and the procedure for the testing of the durability of replacement pollution control devices (Text with EEA relevance).
F6: Inserted by Commission Regulation (EU) 2018/932 of 29 June 2018 amending Regulation (EU) No 582/2011 as regards the provisions on testing by means of portable emission measurement systems (PEMS) and the requirements for universal fuel range type-approval (Text with EEA relevance).
F7: Substituted by Commission Regulation (EU) 2018/932 of 29 June 2018 amending Regulation (EU) No 582/2011 as regards the provisions on testing by means of portable emission measurement systems (PEMS) and the requirements for universal fuel range type-approval (Text with EEA relevance).

Footnotes

f1: Measured or corrected to a wet basis.
f2: Gas engines only.
f3: Use the ambient temperature sensor or an intake air temperature sensor.
f4: The recorded value shall be either (a) the net brake engine torque in accordance with point 2.4.4 of this Appendix or (b) the net brake engine torque calculated from the torque values in accordance with point 2.4.4 of this Appendix.