Leesburg Planning Commission members reviewed a revised draft of data center use standards on Oct. 2 and asked staff to return with tighter, industry-backed language on generator testing, decibel limits and water-use reporting.

Staff member James David of the Department of Community Development walked commissioners through edits to the draft standards for data centers in Section 12-3 (industrial uses). He said staff changed the wording of landscape protections to “avoid all or most established forested areas,” simplified a fenestration standard to require that “30% of the primary facade shall include window or simulated window placements,” and added rooftop screening language intended to respond to cases where neighboring residential areas sit at higher elevation: “When proposed data centers are located on sites that are lower in topography than adjacent residential neighborhoods, rooftop equipment should be screened from the top down view to the extent practicable,” David said.

Why it matters: data centers have large mechanical systems and backup power that can produce continuous noise and significant water demand for cooling. Commissioners said they want enforceable, specific standards rather than aspirational language.

Key changes and points of debate
- Setbacks and screening: staff proposed that ground-mounted equipment adjacent to residential uses be set back 300 feet from the property line and added clearer options for screening, including year-round landscaping or a screen wall. The draft also “strongly encourage[d]” use of existing healthy vegetation rather than relying on new, low-quality plantings.
- Noise limit proposal: staff noted the town’s noise table (Division 22 of the zoning ordinance) already requires 55 decibels at property lines adjacent to residential uses. Commissioners debated whether to require a blanket 55-decibel limit for all data centers regardless of adjacent zoning; several members cautioned that other industrial uses currently have higher permitted boundary levels (65–70 dB depending on adjacency) and that imposing a data-center-only 55 dB requirement could be legally sensitive. The commission reached no final motion but moved to remove a proposed separate “I” noise standard from the draft and directed staff to return with comparisons to Loudoun County’s draft language.
- Generator testing and emergency use: commissioners pressed staff for specifics on generator testing frequency, duration and whether testing should be exempt from decibel limits. Staff proposed language options including limiting testing hours and duration (staff suggested it could be phrased as “testing of emergency backup generators are exempt” or that testing “shall not exceed X hours”) and said they would consult the data center industry coalition for common testing cycles. Commissioner Tuck and others clarified that continuous generator operation during a blackout should be allowed as backup power; the commission asked staff to define what counts as “event of power loss” and to propose notification or verification steps.
- Green-building and submittal requirements: staff removed several weak or easily met items from the green building menu and changed the requirement to “one technique from each list” (site design, energy resource efficiency, etc.). To improve application review, staff proposed requiring applicants for rezonings, special exceptions or town-plan amendments to submit preliminary peak water-usage estimates (top 10 highest water-use days, in gallons per day), a description of cooling technology (air-, water- or hybrid-cooled), and plans for water recirculation or on-site treatment.

Commission directions and next steps
- Staff was asked to consult the data center coalition and return with: typical generator testing cycles (duration, frequency, how many units are tested at once), likely decibel levels during testing and options for time-of-day restrictions; comparisons of Loudoun County’s draft noise language; and industry examples showing whether proposed submittal requirements (water estimates and cooling-technology disclosures) are feasible.
- The commission agreed to eliminate the separate draft noise subsection the staff had highlighted and to rely on the existing Division 22 noise standards while staff refines generator-testing exemptions and any data-center-specific language.

Context and constraints
Commissioners repeatedly noted limits on local authority: emergency power use often occurs when grid operator Dominion or a site operator acts, and the town cannot restore grid service. Several commissioners said practical enforcement and verification (for example, confirming a reported power outage) must be considered when drafting exemptions or time limits for generator use.

Ending: staff said they would gather industry standards, compare county codes, and bring refined language back in a future draft of the zoning rewrite. No formal vote was taken on the draft standards during the Oct. 2 meeting.