Data Center Zoning Ordinances and Overlay Districts: Recent Rules and Standards

For years many codes had no data center use at all, so staff classified projects as warehouses, offices or utilities, and large campuses often went through with administrative site plan review. That is changing quickly. Most new ordinances use three tools in combination. First, a definition and a use table that says where data centers are permitted, where they need a special exception or conditional use, and where they are banned. Second, use-specific standards that apply wherever the use is allowed, such as setbacks, equipment screening and noise limits. Third, an overlay district: a mapped area laid over the base zoning that adds rights, adds rules, or both.

For the difference between by-right, special use and rezoning paths in general, see zoning for data centers. The policy that sits above all of this, and that often drives the ordinance text, is covered in comprehensive plans and future land use maps.

The three largest Northern Virginia counties rewrote their rules within about two years, and the direction was the same in each: fewer by-right approvals and more written standards. These changes matter well beyond Virginia, because other jurisdictions often borrow from them. See the Northern Virginia data center market for the market context.

Fairfax’s rules are the most detailed on separation. Coverage of the amendment reported that data center buildings must be 200 feet from the lot line of adjacent residential property and that equipment such as backup generators must be 300 feet away, with pre- and post-construction noise studies to show compliance with the county noise ordinance.⁴ Site plans accepted by July 16, 2024 could proceed under the old ordinance if approved by July 16, 2025.⁸

Loudoun’s Phase 2 is meant to produce new policy guidance and use-specific standards for data centers and substations, and the county says it is not expected to change the plan or zoning maps.⁹ The published schedule called for a planning commission hearing in November 2026 and board action in early 2027, and in September 2026 the board voted for a temporary pause on certain legislative applications for data centers and substations while that work continues, with a formal resolution scheduled for October 20, 2026.⁹⁶

An overlay lets a locality pick the land where data centers make sense, usually near transmission and away from homes, without rezoning every parcel. Prince William County’s Data Center Opportunity Zone Overlay District allowed data centers by right on land within it. The 2026 amendment substantially reduced the overlay and, under the new framework, most future projects need a special use permit.³ Parcels stay in the reduced overlay only if they meet one or more of five county-defined eligibility pathways, and Venable notes that being vested for development is one route.¹⁰³ Owners had 90 days to qualify, and a motion to cut that period to zero failed 5–3.⁷

Overlays are also appearing outside Virginia. Provo, Utah, amended its data center overlay chapter, including permitted uses and development standards, in an ordinance adopted April 28, 2026.¹¹ Montgomery County, Maryland, introduced a zoning text amendment in January 2026 that would define data centers as a new use, list the zones where they may locate as conditional uses, and add 500 feet to minimum setbacks where a site abuts residential zoning.¹² In July 2026 the council also adopted an 18-month pause on new data centers, so check the adopted text rather than the introduced version.¹³ Neighboring Frederick County adopted a Critical Digital Infrastructure overlay through a comprehensive plan amendment, which the comprehensive plan guide covers.

Distance from residential property is now the most common data-center-specific standard. Rules differ in what they measure from (lot line, district boundary or the house itself) and what they apply to (the building, the equipment yard or both). Separate, larger distances for generators, chillers and other noise-generating equipment are increasingly common.⁴¹⁴

Franklin County, Indiana’s March 2026 draft, for example, would require a 300-foot setback along street frontage and property lines shared with other districts, and would place chillers, exhaust fans and backup generators at least 500 feet from any property line unless a third-party acoustic study shows compliance at the line.¹⁴ On a long, narrow parcel, setbacks like these can remove a large share of the usable area, so run them through a buildable acreage test early. The engineering side is covered in noise, setbacks and buffers.

Noise used to be left to a general county noise ordinance, which often exempted HVAC equipment. Data center rules increasingly close that gap. In 2023 Prince William County removed the commercial HVAC exemption from its nighttime sound limits and directed a review of noise walls, buffering, berms, setbacks, screening and building height for data centers.¹⁵ Fairfax requires noise studies before and after construction.⁴

• Property-line limits in dBA: Greenwood County, South Carolina’s proposed ordinance would cap sound at 60 dBA at the boundary of nonindustrial uses or districts and 70 dBA next to industrial ones.⁵ In July 2026 the county council adopted a one-year moratorium on data centers.¹⁶
• Study-based compliance: some drafts allow equipment closer than the default setback if an acoustic study shows limits are met.¹⁴
• Before-and-after measurement: baseline and post-construction studies, as in Fairfax, create a record that enforcement can use.
• Process-based control: some cities rely on a conditional use permit and council approval rather than fixed numbers.¹⁷

For site screening, the question is not only the limit but where it is measured and at what time of day. A nighttime limit at a residential property line next to the site can govern generator testing schedules, chiller selection and yard placement.

Beyond distance and sound, ordinances now reach into how the building looks and how the campus runs. Fairfax requires equipment to be enclosed or screened by a wall or barrier to reduce visual and noise impacts, and its amendment added design requirements and size limits that vary by location.¹ Loudoun’s Phase 2 is reviewing building height, onsite power generation and energy storage alongside noise and parking.⁹ Aurora, Illinois, as described in APA’s Planning magazine, requires a conditional use permit, limits new facilities to specific industrial and planned development zones, bans evaporative cooling and requires renewable energy and battery backup.¹⁷

Standards on cooling type, onsite generation and storage can affect the power and water plan as much as the site plan, so they belong in early design. Facade, materials and screening requirements are covered in more depth in architectural and visual standards.

Every recent rewrite came with a cutoff. Loudoun let applications accepted before February 12, 2025 continue without special exception approval;² Fairfax let site plans accepted by July 16, 2024 proceed under the prior rules if approved within a year;⁸ Prince William gave owners 90 days to qualify for the reduced overlay.⁷ Venable described the Prince William change as a closing window for by-right development, with vesting through an approved plan of development as one way to stay eligible.³ Windows like these are short, and pending amendments are often the best warning; see data center moratoriums and local restrictions.

1. 01Read the current use table and the data center definition, and confirm the approval path for the parcel’s district.
2. 02Check whether the parcel is in, or near the edge of, a data center overlay, and whether any amendment to it is pending.
3. 03Map the setbacks for buildings and for equipment from every residential lot line and district boundary.
4. 04Find the noise standard, the measurement point and any nighttime limit, and whether studies are required.
5. 05Note design, height, cooling and onsite generation standards that could change the building or utility plan.
6. 06Confirm grandfathering and vesting dates in writing with staff and land use counsel.

Ordinance text changes faster than most acquisition timelines, so treat any summary, including this one, as a starting point and read the adopted text. If you want a parcel checked against current zoning, setbacks and utilities together, get a site reviewed.