The amount of DERs shall be calculated in accordance with the following equation:

1. (a) AL = the activity level during the generation period, expressed as a unit of activity, examples of which are:

   1. (1) Gallons of solids applied for stationary sources of VOCs;
   2. (2) Million BTU for stationary sources of NOx;
   3. (3) 1,000 gallons of fuel burned for area sources;
   4. (4) Number of persons affected for area sources; or
   5. (5) Vehicle miles traveled (VMT) for mobile sources;
2. (b) Subscript A = actual;

3. (c) ER = the lowest allowable or historical actual emission rate that would have been emitted during the generation period, expressed as a mass per unit of production, examples of which are:

   1. (1) Tons of VOC per gallon of solids applied for stationary sources of VOCs;
   2. (2) Tons of NOx per million BTU for stationary sources of NOx;
   3. (3) Tons of VOC or NOx per 1,000 gallons of fuel burned for area sources;
   4. (4) Tons of VOC or NOx per capita for area sources; or
   5. (5) Tons of VOC or NOx per VMT - for mobile sources;
4. (d) E = the amount (typically expressed in tons) of emissions; and
5. (e) n = the number of units comprising the source.

DERs = ₁Sn (AL_A x ER - E_A)

where:

Source. #6441, EXEMPT, eff 1-21-97