1. Real Driving Emission
A proposal for a realistic temperature range Bart Degraeuwe
17 November 2018

2. Main objective
Determine a realistic temperature range for real driving emission measurements.
Following aspects are taken into account:
Temperature distribution over Europe
Population distribution over Europe
Activity patern during the day (rush hours)
17 November 2018

3. Methodology
Ideally the cold start temperature should be registerd during a whole year all over Europe. Then the probability distribution of this temperatures should be determined. Depending on which share (99%, 95%,...) of cold starts the regulator wants to cover, temperature limits can be derived from the temperature distribution. Practically this is not feasable. Hence, the location of cold starts was aproximated with the population density and the time of cold start was aproximated with time factors derived from traffic counts.
17 November 2018

4. Source data
Population for 2006 data were obtained from Eurostat at 1x1km resolution Temperature data at a 28x28 km resolution were used for the year 2009 (a rather average year in terms of temperature) Time factors are based on loop detector data on Belgian roads and give a relative trafic intensity for each hour of the day
17 November 2018

5. Calculation
Calculate for each combination of position (28x28 grid), hour (0-23) and temperature the number of occurrences.
Multiply occurrences with population of the grid cell and the time factor of the hour.
Aggregate this table to get occurrences per temperature and normalize the sum to 1 (100%)
Remark
Because we are looking for a distribution of the temperature the absolute value of the scaling factors (population and time factor) is not important
17 November 2018

6. Results: population and time factor weighted temperature distribution in Europe
Avg: 11.9 degC Std: 7.9 degC
17 November 2018

7. Results: cumulative temperature distribution
Some quantiles:
99% > -7 degC
95% > -2 degC
90% > 1 degC
62% > 9 deg C
17 November 2018

8. Day time temperature quantiles of major European cities
The population and time factor weighted temperature for Europe is very similar to the temperature distribution of the major central European cities (Brussels, Strasbourg, Paris)
17 November 2018