# Commission Delegated Regulation (EU) 2017/654 of 19 December 2016 supplementing Regulation (EU) 2016/1628 of the European Parliament and of the Council with regard to technical and general requirements relating to emission limits and type-approval for internal combustion engines for non-road mobile machinery, Division 3.2.5.3

Extent: E+W+S+N.I.

The deterioration factor (DF) for each pollutant is defined as the ratio of the applied emission values at the emission durability period end point and at the start of the service accumulation schedule (multiplicative deterioration factor).
The manufacturer may request the prior approval of the approval authority for the application of an additive DF for each pollutant may be applied. The additive DF is defined as the difference between the calculated emission values at the emission durability period end point and at the start of the service accumulation schedule.
An example for determination of DFs by using linear regression is shown in Figure 3.1 for NOx emission.
Mixing of multiplicative and additive DFs within one set of pollutants is not permitted.
If the calculation results in a value of less than 1,00 for a multiplicative DF, or less than 0,00 for an additive DF, then the deterioration factor shall be 1,0 or 0,00, respectively.
In accordance with point 3.2.2.1.4, if it has been agreed that only one test cycle (hot-start NRTC, LSI-NRTC or NRSC) be run at each test point and the other test cycle (hot-start NRTC, LSI-NRTC or NRSC) run only at the beginning and end of the service accumulation schedule, the deterioration factor calculated for the test cycle that has been run at each test point shall be applicable also for the other test cycle.
Figure 3.1
Example of DF determination

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Source: https://www.legislation.gov.uk/eur/2017/654/annex/III/division/3/division/3.2/division/3.2.5/division/3.2.5.3 (the official version)
Page: https://openlegislation.uk/eu-regulation-2017-654/annex-III/division-3/division-3.2/division-3.2.5/division-3.2.5.3
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.