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Calculate Fleet Average Emission RatesBased on the Regulation as of September 7, 2012

For each compliance date the regulation requires fleets with more than 500 hp determine if the fleet meets a fleet average emission target rate for that date. The first compliance date is different depending on fleet size:

The fleets must meet progressively lower targets each subsequent year until the final target rate is achieved.

ARB has a calculator that generates the fleet average emission rates given basic engine model year and hp data. For the latest calculator see:

In-Use Off-Road Diesel-Fueled Fleets Regulation

While ARB does have a calculator it is important to understand how the fleet average emission rates are calculated. The in-use fleet average emission rates are calculated as follows.

  1. For each engine in your fleet on Jan 1 find the in use emission rate for that engine (to see the emission rates click on the "Get In-Use Emission Rates" box in the compliance chart). Multiply that emission rate by the engine's max, net hp.
  2. If the engine is equipped with a vehicle diesel emission control system (VDECS) that reduces PM, NOx or both multiply the result of number one above by the appropriate VDECS factor as given below.
    Type of VDECS Installed VDECS Factor
    No VDECS Installed or Level 1 VDECS 1
    Level 2 PM VDECS, not highest level 0.82
    Level 2 PM VDECS, not highest level, with NOx Reduction 1 minus (0.18+(verified % NOx reduction divided by 170)
    Highest Level PM VDECS 0.7
    Highest Level PM VDECS with NOx Reduction 1 minus (0.3 + rerified % NOx reduction divided by 170)
    NOx Reduction only 1 minus (verfied NOx reduction dividied by 170)
    Greater details on VDECS' can be found by clicking on the "VDECS" box in the compliance chart.
  3. Sum the results from two, above for all engines.
  4. Divide that sum by the total fleet hp. The result is your fleet average in-use emission rate.

Note that unless you change the equipment in your fleet or add some type of VDECS your fleet average emission rate will not change.

To calculate your fleet average emission target:

  1. For each engine find the target emission rate for that engine, compliance date, and your fleet size (see "Get Fleet Target Emission Rates"). Multiply that rate by the engine's hp.
  2. Sum the results for all engines.
  3. Divide that sum by the total fleet hp. The result is your fleet average target emission rate.

Note that permanent low use, and year-by-year low use vehicles are excluded from the calculations. For details on these exemptions click on the box "Permanent and Year-By-Year Low Use Equipment" in the compliance chart.