The reference work and reference CO2 mass of an engine type, or for all engine types within the same engine family, shall be those specified in points 11.3.1 and 11.3.2 of the addendum to the EU type approval certificate of the engine type or the engine family, as set out in Annex IV to Commission Implementing Regulation (EU) 2017/656.

In accordance with Standard ASTM E 29-06b (Standard Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications), the final test results shall be rounded in one step to the number of places to the right of the decimal point indicated by the applicable exhaust emissions limit values set out in Article 18(2) of Regulation (EU) 2016/1628 plus one additional significant figure.

The brake-specific gaseous pollutant emissions e gas (g/kWh) shall be calculated for each averaging window and each gaseous pollutant in the following way:

Where:

mi is the mass emission of the gaseous pollutant during the ith averaging window, g/averaging window, W(t 2, i ) – W(t 1, i ) is the engine work during the ith averaging window, kWh.

The conformity factors shall be calculated for each individual valid averaging window and each individual gaseous pollutant in the following way:

Where:

egas is the brake-specific emission of the gaseous pollutant, g/kWh; L is the applicable limit, g/kWh.

The conformity factors shall be calculated for each individual averaging window and each individual pollutant in the following way:

With

${\mathrm{CF}}_I=\frac{m_i}{m_{{\mathrm{CO}}_2}\left(t_{\mathrm{2,}i}\right)-m_{{\mathrm{CO}}_2}\left(t_{\mathrm{1,}i}\right)}$ (in service ratio) and ${\mathrm{CF}}_C=\frac{m_L}{m_{{\mathrm{CO}}_{\mathrm{2,}\mathrm{ref}}}}$ (certification ratio)

Where:

mi is the mass emission of the gaseous pollutant during the ith averaging window, g/averaging window, $m_{{\mathrm{CO}}_2}\left(t_{\mathrm{2,}i}\right)-m_{{\mathrm{CO}}_2}\left(t_{\mathrm{1,}i}\right)$ is the CO2 mass during the ith averaging window, g; $m_{{\mathrm{CO}}_{\mathrm{2,}\mathrm{ref}}}$ is the engine CO2 mass determined for the NRTC, g, mL is the mass emission of gaseous pollutant corresponding to the applicable limit on the NRTC, g.