Methoden voor de berekening van de emissies door mobiele ... - CBS

In-use compliance programme and dedicated measuring programmes
Since 1987, the basis for the recent emission factors of regulated components (CO, VOC, NOx and
PM10) has been the annual in-use compliance programme of TNO Science and Industry. As part of
this programme, every year approximately 150 passenger cars and 30 trucks (including 50 and 10
different types, respectively 10 ) have been tested, primarily using the type approval test cycle.
In addition, supplementary (more practice-oriented) measurements are conducted on the available
vehicles. The vehicles that are tested are selected so that they provide a good reflection of the total
fleet of vehicles on Dutch roads over the years. In this process, the study takes account of vehicle
sales, type of fuels, vehicle class (Euro1, Euro2, etc.) and year of manufacturing. The vehicles were
obtained by writing to the users of the selected vehicle types and asking whether or not they would be
willing to submit their vehicle for a test. The response to this request is relatively low, about 25%, and
has been relatively constant in recent years. As part of the final choice of the vehicles to be tested, an
important criterion is that there is sufficient spread in mileages and regular maintenance. In addition,
both privately owned and leased vehicles are tested. In this way, the tested vehicles reflect the
average usage and maintenance condition of the total fleet of vehicles in the Netherlands.
When they are submitted for testing, the vehicles are subjected to an ECE type approval test, after
which the measurement values are compared with the type approval values for the relevant vehicle
(how high were the emissions of this type when the official type approval took place?) and with the
applicable emission norms. The vehicles that did not pass the test were adjusted and measured again.
In recent years there has been a sharp decline in the number of cars that don’t comply to the existing
norms. On average petrol fuelled cars always comply, for diesel cars this is the case to a lesser
degree.
For the purpose of calculating the emissions from passenger cars TNO uses the measured emission
factors before any maintenance is conducted. As a result, poorly tuned and/or poorly maintained
vehicles are also included in the emission calculation.
During the course of time the emphasis of the in-use compliance programme has moved more and
more to map out real-worls emission performances and not the execution of Euro type approval test
cycles on new vehicles. This is to prevent the underestimation of the real vehicle emissions.
VERSIT+ warm basic emission factors (BASw)
Since 2005, TNO Environmental Studies and Testing (TNO EST) uses the VERSIT+ 11 Traffic situation
model [ref 113: Smit et al, 2007] to calculate the basic emission factors from the emission measurements
database. With the use of VERSIT+ exact emission factors can be calculated for different traffic
situations and scale levels [ref 119 Ligterink, N.E., Lange, R. de, 2009]. The emission factors follow from
various analysis fed by different kinds of measuring data.
VERSIT+ LD (light duty) has been developed for light vehicles, as passenger cars and vans, with
which accurate emissions can be predicted of streams of traffic in specific traffic situations [ref 111 : Smit
et al, 2006a, 2007]. For the dsetermination of the basic emission factors (BASw) of light duty vehicles first
the driving behaviour dependance and the statistical varation per vehicle has been investigated. Next
the results have been used in a model with 42 light duty categories for each of the 5 emission
components. The resulting model separates optimal driving behaviour and vehicle category
dependances.
VERSIT+ HD (heavy duty) [ref: Riemersma, 2004] is used to predict the emission factors of heavy
duty vehicles (lorries, road tractors and buses). For older vehicles VERSIT+ HD is used with input
based on European measurement data. These data have been obtained with less realistic tests,
meaning that in some cases only the engine has been tested and in other cases measurements have
been executed with several constant engine loads and engine speeds (rpm). For newer vehicles
(Euro-III – Euro-V) measurement data are available which are closer to the real world practice. These
new data are based on realistic driving behaviour, both from on-road measurements and
measurements on test stands, have been used in a model to represent emissions during standard
driving behaviour. The emission factors for buses often originate from test stand measurements with
realistic driving behaviour for regular service buses.
For the determination of the emission factors the PHEM model is used which has been developed by
the Graz University of Technology. The input is, just as for VERSIT+ LD, composed of speed-time
diagrams which make the model suiontable for the prediction of emissions in varying traffic situations.
For the Emission Registration emission factors per vehicle class are calculated, specifically for the
Dutch situation.
10
vehicle type = manufacturer + model + motor type, for example Ford Escort 1.3 ICL
11
VERkeers SITuatie Model Plus, meaning traffic situation model plus
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