How To Calculate Yearly And Rolling Totals And Rolling Averages
This guidance document is advisory in nature but is binding on an agency until amended by such agency. A guidance document does not include internal procedural documents that only affect the internal operations of the agency and does not impose additional requirements or penalties on regulated parties or include confidential information or rules and regulations made in accordance with the Administrative Procedure Act. If you believe that this guidance document imposes additional requirements or penalties on regulated parties, you may request a review of the document.

Form #:  02-130
Guidance Documents
Revised: 9/29/16

There are various ways in which a permit may limit the emissions from an operation. Although some limits may appear similar, they are calculated much differently. The following examples explain the differences between permit limits based on calendar years, rolling totals, and rolling averages.
The chart below provides an example of a painting operation, which began in March 1998. This operation has a permit that provides limitations on the amount of paint it can use. The monthly paint usage for 1998, 1999, and 2000 are indicated in the left column.