Continuous low-frequency noise from cooling plant reaches homes at levels ordinances are not written to measure

Observable evidence

The best independent property-line dataset is the Lyver acoustic study commissioned for Prince William, Fauquier and King George Counties, Virginia in December 2022, which measured 25 receptor locations and modelled full buildout. At Oak Valley in Catharpin, 180 feet from the nearest facility, ambient measured 48.6 dB(A) and was projected to reach 77.2 dB(A). At the Great Oak HOA in Manassas, readings ranged 58.5 to 64.3 dB(A) with projected increases of 3 to 15 dB(A). Most modelled areas exceeded applicable day and night limits by 7 to 16 dB(A) (Lyver study).

For scale, WHO Europe recommends night noise below 40 dB(A) outside bedrooms and below 30 dB(A) inside them (WHO Europe).

The measurement problem, which is the core of this issue

The harm residents describe is not loudness but tonality and persistence: a steady hum that does not stop and cannot be habituated to. Ordinances measure A-weighted broadband sound, which de-emphasises exactly the low-frequency content at issue. Prince William County's March 2025 draft ordinance proposes adding dBC and octave-band limits explicitly because "the A-weighted scale doesn't effectively address the low-frequency noise generated by Data Centers", citing a 90 Hz tone observed at the Tanner Way facility (Prince William County board presentation).

Two structural defects compound this. Prince William's existing ordinance exempts air conditioning units, and most municipal noise ordinances "were written to address noisy block parties" rather than continuous industrial plant (EESI). Reported source levels include cooling towers up to 70 dBA at 400 feet and industrial generators to 105 dB.

Who is affected

Households within a few hundred metres of cooling plant. In Northern Virginia, where roughly 300 facilities operate, about one third sit within 200 feet of residentially zoned land (EESI).

Litigation is now the route of last resort

In Granbury, Texas, TIME recorded peaks of 91 dB, nightly levels of 70 to 90 dB, and 72 dB inside a resident's bedroom at midnight, with a county constable logging more than 35 readings above 85 dB in 2024; more than 40 residents reported related medical issues (TIME), and two dozen sued the operator in October 2024 (Earthjustice). Important caveat: that facility is a Bitcoin mine, not an AI data-center, and Texas's 85 dB statutory limit is the highest in the United States, so it illustrates the mechanism rather than the typical case.

In June 2026, residents of Southaven, Mississippi sued xAI, SpaceX and MZX Tech over "high-pitched squealing, continuous engine roaring, low-frequency rumbling, and tonal humming", alleging sleep loss, headaches and tinnitus. As reported, the complaint contains no decibel measurements (Memphis Flyer).

Scope

This issue is the emission and its regulation. The separate question of whether the health evidence base supports a specific limit is handled as a sub-issue, because the epidemiology currently in use was not measured on this source type.

Impact if unaddressed

Noise is the most common trigger of local opposition and the cheapest harm to design out at the build stage. Left to post-hoc complaint, it is resolved either by expensive retrofit or by litigation, and it hardens communities against projects whose other impacts might have been acceptable.