Real driving emissions : 2017 assessment of Portable Emissions Measurement Systems (PEMS) measurement uncertainty

Regulation 2016/427 introduced on-road testing with Portable Emissions Measurement Systems (PEMS) to complement the laboratory Type I test for the type approval of light-duty vehicles in the European Union. A NOx conformity factor of 1.5 will apply from January 2020/2021. This conformity factor includes a margin of 0.5 to account for the additional measurement uncertainty of PEMS relative to standard laboratory equipment. Said margin (and also the PN margin, initially set at 0.5 by Regulation (EU) 2017/1154 (RDE3), has to be reviewed annually (Recital 10 of Regulation 2016/646). This report summarizes the first review of the NOx margin and lays out the framework for future margin reviews. Since the PN margin was first set in 2017, it was not included in the 2017 review exercise. Based on experimental data received by the stakeholders, technical improvements of PEMS and assumptions of possible zero drift during the tests, a NOx margin of 0.24 to 0.43 was calculated.