Towards RDE cold-start provisions Contribution to the RDE working group 25 January 2016 European Commission - Joint Research Centre (JRC) IET - Institute for Energy and Transport Sustainable Transport Unit

Background • Current Type 1 (20-30 oC) and Type 6 tests (-7 oC) cover cold start; a dedicated cold-start test does not exist Cold start emissions are recorded in RDE but excluded from calculations Absence of vehicle conditioning Low repeatability and reproducibility of test conditions may lead to high variability of warm-up durations and cold start emissions Cold start contributes little to the overall emissions of comparatively long (up to 2h) RDE tests Implementation of dedicated cold-start provisions as part of the 3rd RDE package

Addressing cold-start - Options Option 1 – Status quo: Cold-start assessment via Type 1 and Type 6 tests; exclusion from RDE Option 2: Cold-start inclusion in RDE data evaluation but no dedicated assessment Option 3: Cold-start inclusion in RDE data evaluation with specific pre- conditioning requirements but no dedicated assessment Option 4: Dedicated cold-start provisions (including preconditioning and dedicated evaluation of emissions as part of the RDE procedure)

RDE - Preconditioning Engine, tubing, and after-treatment Parameter ranges rather than precise values Parameters to be controlled: Temperature range for vehicle storage (Status of periodically regenerating after-treatment systems) Others Minimum duration of preconditioning Standardization increases repeatability of tests but also the feasibility of defeat strategies

RDE - Driving Cold-start is typically followed by urban driving Critical parameters: Idling shares Maximum uninterrupted idling duration Maximum vehicle speed Driving dynamicity (v*a+) Test duration Proposal: RDE provisions could provide starting point for empirical assessment Focus on real-world driving data

Definition of cold start Options: Current “protective” definition: 5 min or until coolant has reached 70oC New definition for assessing cold start performance Time or distance based; first MAW Traces of coolant/oil temperature, etc. Data evaluation (e.g., at cranking, at a given coolant temperature, etc.) Applicability to hybrid vehicles Average speed Distance travelled in 5 min Distance travelled in 10 min Time to travel 2 km Time to travel 3 km 35 km/h 2.9 km 5.8 km 3:25 min 5:08 min 30 km/h 2.5 km 5.0 km 4:00 min 6:00 min 25 km/h 2.1 km 4.2 km 4:48 min 7:12 min 15 km/h 1.3 km 8:00 min 12:00 min 10 km/h 0.8 km 1.7 km 18:00 min

Empirical findings Empirical results of cold-start emission tests Laboratory tests Gasoline engines Diesel engines Vehicle ID G1 G2 G3 D1 D2 D3 Engine displacement [ccm] 2000 1200 3000 Number of cylinders 4 Engine rated power [kW] 155 90 110 100 Mileage [km] 11200 5000 13500 30000 14500

Empirical findings Normalized NOx emissions over the NEDC Gasoline vehicles emit 4 to 10 times more NOx during UDC1 than over the NEDC Diesel vehicles emit 2 to 3 times more NOx during the UDC1 than over the NEDC Three way catalyst appears to effectively reduce NOx immediately after UDC1 (195sec) Between-vehicle variability of cold-start emissions is substantial – larger vehicle sample required

Evaluation of results Weighing of cold-start vs. hot engine operation based on share of cold start operation in normal real-world vehicle operation Assessment of typical trip durations in Europe Assessment of daily frequency of trips and the occurrence of cold-start Generic weighing factors

Evaluation of results Assessing the average length of on-road trips Empirical insight to be added based on literature study WLTP data base suggests trips in Europe cover on overage 10-12 km WLTP data in line with literature findings (analysis to be expanded) Weighing time or distance based (e.g., relative to the average trip length Source Average trip length WLTP data base (430,000 km and 35, 850 short trips; Steven, pers. Communication) 10.5 km (incl. trips <1,000 m) 12.0 km (excl. trips <1,000 m) Pasaoglu et al. (2012) 15-25 km; 2-3 trips per day based on a web survey of 600 participants in 6 EU Member States De Gennaro et al. 2014 5-20 km; parking duration 2-12 h in two Italian cities based on 28,000 vehicles and 36*106 km

Outline of activities Principle choice on Options 1-4 Prescription of vehicle preconditioning (thermal conditions, duration, status of regenerating after-treatment systems) Decision on additional requirements regarding driving conditions during cold start (e.g., idling shares, driving dynamics) Decision on a time/distance-based definition of cold-start Evaluation of results: Weighing factors combining cold start emissions and the hot emissions as determined through the RDE data evaluation

Conclusions and next steps Measuring cold-start emissions does not present an analytical challenge However, vehicle conditioning and controlling for driving dynamicity is important Choice of cold-start distance to be supported by empirical data Weighing with driving under hot engine conditions requires thorough data analysis Hybrid vehicles demand attention

Contacts Pierre Bonnel pierre.bonnel@jrc.ec.europa.eu Theodoros Vlachos theodoros.vlachos@jrc.ec.europa.eu Barouch Giechaskiel barouch.giechaskiel@jrc.ec.europa.eu Francesco Riccobono francesco.riccobono@jrc.ec.europa.eu Martin Weiss martin.weiss@jrc.ec.europa.eu