From laboratory to road – Real Driving Emissions

Abstract

In European emission type approval during the past years the exhaust emission limits have been reduced significantly. Although air quality was improved from 1990 on, a high percentage of the European population is exposed to air pollutant concentrations above European limit values, mainly on particles, nitrogen dioxide (NO2) and ozone (O3).

Exhaust emissions of passenger cars and light duty trucks in Europe are measured by using the “New European Driving Cycle” (NEDC) under well defined ambient conditions in a laboratory. The NEDC represents only a small part of all driving conditions in real traffic. On 03.02.2016 the European Parliament decided that exhaust emissions in real traffic (Real Driving Emissions = RDE) shall be measured in Europe by using Portable Emission Measurement Systems (PEMS). Due to European air quality regulations NOx emissions are the main issue of RDE. European Commission is also interested in particle measurement especially on gasoline cars with direct injection.

When measuring emissions in real traffic numerous influencing factors have to be considered. Besides variable ambient conditions changing traffic situations affect the results of such measurements. This complex set of influencing factors has to be addressed by defining route requirements and boundary conditions. An elaborate data evaluation has been created. While the Moving averaging windows method (MAW; or EMROAD by JRC) is based on CO₂ emissions, for the Standardized wheel power frequency distribution method (SPF; or CLEAR by TU Graz) the wheel power is used for normalizing exhaust emissions.

Due to the fact that RDE are measured in real traffic, this new method will be challenging for all parties involved.