Data Center Zoning, Noise, and Power Rules: Loudoun County vs. Prince William County, Virginia

By Reginald “Reggie” Butler Jr., Broker/Owner, CENTURY 21 ENVISION | Updated October 2026 | 8-minute read

Northern Virginia’s “Data Center Alley” is the largest data center market in the world, and the two counties at its center have tightened the rules fast. For landowners, buyers near industrial corridors, and anyone weighing a sale to a developer, the key changes are where data centers are allowed, how loud they can be, how close they can sit to homes, and how they get power.

Loudoun County

Zoning: by-right approval is gone

On March 18, 2025, the Loudoun Board of Supervisors voted 7–2 to make data centers a special exception use in the districts where they had been allowed by right. Every new application now needs a Planning Commission hearing and a Board hearing. Applications filed before February 12, 2025 kept the old rules if the project is more than 500 feet from homes and is actively pursued; growing a project’s square footage by more than 5% ends that protection. The same day, the Board amended the Comprehensive Plan to make data centers a “conditional” use in several planned place types.

Noise

Loudoun’s limit is 55 dBA at the property line of residential property. Developers must submit a noise study at site plan review and another one 1 to 12 months after the first certificate of occupancy. Rules on tonal and low-frequency noise are expected in 2027.

Coming next: Phase 2 standards (drafts, not adopted)

Loudoun’s draft data center standards are scheduled for a Planning Commission hearing in February 2027 and a Board hearing in July 2027. The draft proposes setting substations back 500 feet from residential

(air-insulated) or 200 feet (gas-insulated), up from 100 feet today; requiring a 20-foot opaque screen around substations; setting on-site power plants at least 200 feet from residential with at least 2 acres per 100 MW of generation; and requiring a noise assessment for homes and schools within 500 feet.

Prince William County

Zoning: overlay shrunk, by-right ended

On September 22, 2026, Prince William supervisors unanimously voted to shrink the Data Center Opportunity Zone Overlay District from about 9,700 acres to about 3,641 (final boundaries pending) and end by-right approval for most new data centers, which will now need a special use permit. Owners have a 90-day window to qualify for the smaller overlay. Countywide performance standards, including setbacks from homes, have been signaled but not released.

Noise

Since February 2023, data center cooling equipment has been held to the county’s 55-decibel residential limit from 10 p.m. to 9 a.m., after the Board removed the nighttime exemption for commercial HVAC. In October 2025 the Board adopted a new noise ordinance that adds C-weighted limits, which capture the low-frequency hum neighbors complain about. It has no grandfathering for existing facilities.

The Digital Gateway is dead

The PW Digital Gateway rezonings were voided in August 2025 for improper public notice. The Court of Appeals upheld that ruling on March 31, 2026, the county chose not to appeal, and QTS withdrew its appeal in July 2026, ending the project.

Statewide rules that apply in both counties

Site assessments (Code of Virginia § 15.2-2209.4, in effect July 1, 2026): for any facility expected to need 100 MW or more, the locality must require a site assessment before a rezoning, special exception, or special use permit. It must include a sound profile for homes and schools within 500 feet, and the utility must describe the substations and transmission voltage needed.

Generators: starting July 1, 2026, Virginia DEQ requires Tier 4-equivalent emissions for new or modified backup generators.

Power delivery: Dominion Energy’s new GS-5 rate class, approved by the State Corporation Commission in November 2025, takes effect in January 2027 for customers drawing more than 25 MW. It uses 14-year contracts with minimum payments of 85% of contracted transmission and distribution demand and 60% of generation demand. In practice, the grid connection queue — reported at more than 40 GW in Dominion’s territory — is the real limit on new capacity.

Tax incentives: Virginia’s sales and use tax exemption on data center equipment remains in place for operators investing $150 million and creating 50 jobs at 1.5 times the local average wage ($70 million and 10 jobs in distressed localities). It runs through July 1, 2035. The 2026 state budget also added a charge of $0.011 per kWh on data center electricity from July 1, 2026 through June 30, 2028.

Comparison table: Data Center Alley at a glance

Frequently asked questions

Can you still build a data center by right in Loudoun or Prince William County?

Generally no. Loudoun made data centers a special exception use in March 2025, and Prince William ended by-right approval for most new sites in September 2026, so both require a public hearing and a Board vote, aside from grandfathered projects.

Is there a megawatt cap on data centers in Northern Virginia?

No. Neither county nor the state caps capacity per site or countywide. The 100 MW mark triggers Virginia’s site assessment requirement, and 25 MW triggers Dominion’s GS-5 rate class. Grid connection capacity is the practical limit.

What noise limits apply to data centers?

Loudoun limits noise to 55 dBA at residential property lines and requires noise studies before and after opening. Prince William holds data centers to its 55-decibel nighttime residential limit and added C-weighted limits for low-frequency noise in 2025.

How far must data centers be from homes?

Neither county has a final adopted standard. Loudoun’s draft would set substations 500 feet (air-insulated) or 200 feet (gas-insulated) from residential. State law requires a sound profile for homes and schools within 500 feet for projects of 100 MW or more.

What tax incentives do data centers get in Virginia?

A state sales and use tax exemption on equipment for operators investing $150 million and creating 50 qualifying jobs, through July 1, 2035. Locally, computer equipment is taxed at $4.15 per $100 in Loudoun and

$4.50 in Prince William for 2026.

This article is general information, not legal advice. Data center rules in both counties are changing quickly; confirm current requirements with the county planning office and a land use attorney.