Loudoun County, VA Noise from Specific Sources: Generator Noise (2026)

Loudoun County's treatment of generator noise reflects the unique reality of Ashburn's data center concentration. Under Zoning Ordinance Section 5-1507(F)(4), sounds created by generators and accessory equipment operating during an emergency or at the request of a utility, and the testing of said generators, are exempt from the decibel limits in Table 5-1507(E). Similarly, Chapter 654.02(e)(4) exempts sound produced by power generators during power outages and other emergency situations. However, non-emergency generator operation at commercial and industrial facilities must comply with standard noise limits: 55 dBA at residential property lines, 60 dBA at mixed-use residential, 65 dBA at commercial, and 70 dBA at industrial receiving properties. Data center backup generators are a major issue in eastern Loudoun. A single large data center campus may have 50-100+ diesel backup generators, each rated at 2,000-3,000 kW. Regular testing is required for reliability, and multiple generators running simultaneously during tests or grid events create substantial noise. The March 2025 Phase 1 data center regulations now require Special Exception approval with conditions including limited generator testing hours and fully screened mechanical equipment areas. The Phase 2 regulations (September 2025) are developing enhanced performance standards specifically addressing generator testing schedules and noise mitigation for data center facilities adjacent to residential communities.