EPA Clean Air Act Data Center Resource Hub: Permitting & Compliance Takeaways

What EPA released on December 11, 2025

EPA’s new Clean Air Act Resources for Data Centers webpage is designed to help developers:

• Determine whether planned equipment triggers air permitting requirements
• Understand how Clean Air Act programs like New Source Review (NSR) and Title V may apply
• Find permitting and compliance guidance that is often scattered across multiple EPA pages and memos

EPA also notes that staff are available to consult with permitting authorities and sources case-by-case to identify existing data, models, and tools to demonstrate compliance and, as appropriate, apply available discretion and flexibilities in the permitting process.

Resource Page: https://www.epa.gov/stationary-sources-air-pollution/clean-air-act-resources-data-centers

Why this matters for data center projects

Data centers are often viewed as “clean” facilities, but air permitting complexity typically comes from the power side of the project, especially:

• Backup generators (often large stationary engines)
• Stationary combustion turbines (where used)
• Other emergency or on-site generation equipment

Depending on design, size, fuel type, and location, these units can trigger requirements under federal programs such as NSPS, NSR (PSD or nonattainment NSR), and potentially NESHAP.

Key topics covered in EPA’s data center resource hub

1) Common air requirements for typical data center power equipment

EPA calls out equipment frequently used at data centers, including stationary combustion turbines, stationary engines, and nonroad engines, and points users toward relevant Clean Air Act program requirements that may apply.

Resource Page: https://www.epa.gov/stationary-sources-air-pollution/clean-air-act-resources-data-centers

2) “Potential to Emit” and strategies to avoid major source permitting where appropriate

A major theme is Potential to Emit (PTE), which can trigger more stringent permitting even when actual emissions may be lower.

EPA highlights approaches where projects may use federally enforceable permit limits (often referred to as a “synthetic minor” approach) to keep PTE below major source thresholds, which may allow a project to avoid major NSR and Title V requirements depending on site specifics and permitting authority requirements.

“Options for Limiting PTE” memo (Jan. 25, 1995): https://www.epa.gov/sites/default/files/2015-08/documents/ptememo.pdf
“Limiting Potential to Emit” guidance (June 13, 1989): https://www.epa.gov/sites/default/files/2015-07/documents/lmitpotl.pdf

3) Construction sequencing and the meaning of “begin actual construction”

Certain Clean Air Act requirements are triggered when “actual construction” begins. EPA links to guidance interpreting “begin actual construction” as tied to physical, permanent construction activities on an emissions unit (not necessarily all site work), which can affect whether some non-emitting construction activities may proceed while permitting is in progress.

EPA response letter (Sep. 2, 2025): https://www.epa.gov/system/files/documents/2025-09/tsmc-arizona-begin-actual-construction-epa-response-letter.pdf

EPA also points to a rulemaking effort to revise the NSR definition of “begin actual construction,” which—if finalized—may provide additional clarity and flexibility.

Unified Agenda (RIN 2060-AW84): https://www.reginfo.gov/public/do/eAgendaViewRule?pubId=202504&RIN=2060-AW84

4) Aggregation and “single source” questions

The resource hub points users to rules and guidance addressing:

• When multiple project changes must be aggregated when evaluating NSR applicability
• How “common control” and “adjacent” concepts may affect whether nearby emitting activities are treated as a single source for permitting purposes

“Adjacent” guidance (Nov. 26, 2019): https://www.epa.gov/sites/default/files/2019-12/documents/adjacent_guidance.pdf

5) Combustion turbine standards that may be relevant

Because turbines can be part of some data center power strategies, the hub points to federal activity related to updates and technology reviews for stationary combustion turbine standards.

Federal Register (Dec. 13, 2024): https://www.federalregister.gov/documents/2024/12/13/2024-28619/review-of-new-source-performance-standards-for-stationary-combustion-turbines-and-stationary-gas
Unified Agenda (RIN 2060-AW21): https://www.reginfo.gov/public/do/eAgendaViewRule?pubId=202504&RIN=2060-AW21

6) Air quality modeling and testing guidance

For projects that trigger major NSR permitting (PSD or nonattainment NSR), air modeling can be central to demonstrating compliance. EPA links to modeling resources and preferred tools.

EPA SCRAM Modeling Guidance: https://www.epa.gov/scram/clean-air-act-permit-modeling-guidance

Practical takeaways for data center owners and developers

If you are planning a new data center or expanding an existing site, consider these steps to reduce schedule risk and late-stage permitting surprises:

1. Inventory power-related emission sources early (generators, turbines, engines, fuel storage).
2. Estimate PTE early and stress-test worst-case assumptions, since PTE can drive major permitting.
3. Evaluate whether enforceable permit limits are appropriate to help keep the project in a minor source category where feasible.
4. Plan construction sequencing carefully and document which activities are tied to emissions units versus general site work.
5. Assess aggregation and common control questions if you have multiple parcels, phased builds, or nearby operations.
6. Engage the permitting authority early and consider outreach to the appropriate EPA Regional office when questions are novel or schedule-critical.

How Encino can support data center air compliance planning

Encino supports Data Center facilities with emissions-focused compliance services that align with air permitting requirements including:

• Emissions testing to support permit conditions and compliance demonstrations
• Engine and turbine-related testing support where applicable
• Stack testing and related measurement programs (when required by permit or regulation)
• Emissions monitoring strategy support for facilities that need a defensible data approach over time

If your team is evaluating air permitting pathways for backup generation or on-site power, it’s often most efficient to align compliance strategy before equipment is finalized and installed, while design decisions remain flexible.

A quick note on scope

This article is for general informational purposes. Clean Air Act applicability and permitting strategy are highly site-specific, and permitting authority requirements and interpretations can vary.