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Facility Emissions Inventory Calculator

Aggregate emissions from multiple sources and compare against Title V and PSD thresholds

Free facility emissions inventory calculator. Enter emissions from multiple sources (boilers, generators, process equipment, coating lines) and get facility-wide totals for NOx, SO2, VOC, CO, PM10, and PM2.5 in tons per year. Compares totals against Title V major source thresholds with dominant source identification and percentage contribution breakdown.

Pro Tip: When building your inventory, do not forget fugitive emissions. Equipment leaks, material handling, haul roads, and cooling tower drift can add up. Many facilities have been surprised to find that fugitive PM or VOC pushes them over a major source threshold after combustion sources alone were well below.

Calculate PTE for individual combustion sources

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Screen modifications against PSD thresholds

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Look up AP-42 emission factors

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Facility Emissions Inventory Calculator
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How It Works

  1. Add Emission Sources

    Enter each source at your facility by name and its annual emissions for each pollutant. Start with your largest combustion sources, then add process emissions, coating operations, and fugitive sources.

  2. Enter Emissions Per Pollutant

    For each source, enter annual emissions in tons per year. If you have emissions in lb/hr, multiply by annual operating hours and divide by 2,000 to convert to tpy.

  3. Review Facility Totals

    The calculator sums all sources per pollutant and compares against the 100 tpy Title V threshold. Watch for pollutants approaching 80 tpy or higher.

  4. Identify Dominant Sources

    The breakdown shows which source contributes the most to each pollutant. This helps prioritize emission reduction projects and control equipment investments.

Built For

  • Environmental managers preparing annual emission inventories for state reporting
  • Consultants compiling facility-wide emissions for Title V permit applications
  • Plant engineers identifying which sources to target for emission reductions
  • Operations staff tracking emissions against permit limits across multiple units
  • Corporate teams comparing emission profiles across multiple facility locations

Assumptions

  • User-entered values represent annual emissions in tons per year.
  • Title V major source threshold is 100 tpy for criteria pollutants in attainment areas.
  • All entered sources are located at the same facility (same property boundary).

Limitations

  • Does not calculate emissions from raw inputs - users must provide pre-calculated tpy values.
  • Does not include HAP-specific tracking or HAP major source thresholds.
  • Does not account for fugitive emissions unless manually entered.
  • State-specific inventory formats and reporting requirements are not addressed.

References

  • Clean Air Act Section 502(a) - Title V Permit Program Applicability
  • 40 CFR Part 70 - State Operating Permit Programs
  • EPA Emission Inventory Improvement Program (EIIP) Guidance
  • State-specific emission inventory reporting guidance documents

Frequently Asked Questions

A complete inventory includes all point sources (stacks), fugitive sources (equipment leaks, material handling), area sources (storage piles, ponds), and mobile sources on site. For Title V applicability, include every emission unit that could contribute to the facility-wide total. Common sources that get missed: cooling towers, parts washers, painting operations, emergency engines, and loading/unloading operations.
For criteria pollutants (NOx, SO2, CO, PM10, PM2.5, VOC) in attainment areas, the threshold is 100 tons per year of any single pollutant. For HAPs, it is 10 tpy of any single HAP or 25 tpy of all HAPs combined. In ozone nonattainment areas, VOC and NOx thresholds are lower (25-100 tpy depending on classification). If any single pollutant exceeds its threshold, the facility is a major source for all pollutants.
Most states require annual emission inventory updates, typically due by March or April for the previous calendar year. Title V facilities submit annual compliance certifications. Some states also require triennial or quinquennial inventory updates for minor sources. Keeping your inventory current helps avoid surprises when planning equipment additions or modifications.
Disclaimer: This calculator provides a preliminary facility emissions summary. A complete emissions inventory for regulatory purposes must include all emission sources, fugitive emissions, and applicable emission estimation methodologies. Consult your state environmental agency for specific inventory requirements and reporting formats.

Learn More

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AP-42 emission factors, material balance, continuous monitoring, stack testing methods, and how to build an accurate annual emissions inventory for your facility.

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