How Loud Is a Data Center Allowed to Be? The Decibel Limits in the Ordinances That Govern Real Campuses

Every row below was built from the ordinance or zoning text itself, fetched from the jurisdiction's code library, not from a summary. Limits are for a residential receiving property unless noted. Daytime and nighttime hours are listed where the code defines them. Where a jurisdiction has no decibel number, we say so rather than borrow a figure from somewhere else.

How to cite this table: SueDataCenters.org, "Data Center Noise Limits by Jurisdiction," updated September 3, 2026, with the code sections listed in each row. Journalists and researchers may reproduce the table with attribution. The code links in the sources list are the primary record; check them for amendments after our update date.

Two patterns jump out. First, the jurisdictions with the most data centers have the most specific rules, and they are getting more specific: Loudoun requires noise studies, Prince William added a C-weighted standard in 2026, Chandler built a baseline regime. Second, the places where the newest and loudest facilities have landed, Memphis, Southaven, Newton County, are the ones with no number, or with a number left over from an exemption. That is not an accident. It is the gap the plaintiffs in Haley v. xAI are litigating through.

Almost every limit above is written in dBA, A-weighted decibels. The A filter mimics how the human ear responds at moderate volumes, which means it sharply discounts low frequencies. Prince William County's own definition puts it plainly: the A weighting "de-emphasizes against the lower frequencies." The C weighting, by contrast, has "much less de-emphasis of low frequencies" and, in the county's words, "is commonly used where low-frequency content or peak/impulsive noise is of concern." The Z or flat weighting counts everything from 10 Hz to 20 kHz equally and is used for octave band work.

This matters because a data center's signature sound is not a bang. It is a steady tonal drone from chillers, condenser fans, cooling towers, transformers, and generators, much of it at the low end of the spectrum. A facility can read 54 dBA at the fence, comfortably under a 55 limit, while the C-weighted level is 15 or 20 decibels higher and the bedroom walls are humming. Loudoun County says as much on its own data center noise page: its dBA standard does "not capture low frequency noise or the discomfort caused by steady tonal sounds," and the county "does not currently have policy or regulatory language specific to tonal noise or low frequency noise." That is the largest data center market in the world describing the hole in its own rule.

The cases on our tracker are being filed in that hole. The Fairwater class action in Mount Pleasant is about chillers, cooling towers, air handlers, and condenser fans running around the clock, and Microsoft's own response acknowledged a tonal humming sound attributed to cooling fans. The Southaven complaint alleges low-frequency vibration residents can feel as well as hear. The North Tonawanda complaint's vibration claims describe sound below what a standard A-weighted reading captures. Only two jurisdictions in our table have written a rule that would even register those complaints: Prince William, with its 73 and 68 dBC caps on steady tonal sound, and Mount Pleasant, whose octave band table sets a separate ceiling for the 0 to 75 Hz band. Everywhere else, the ordinance and the complaint are measuring different things.

The ordinance limits are political numbers. The health numbers are lower. The World Health Organization's Night Noise Guidelines for Europe (2009) conclude that an L_{night,outside} of 40 dB "should be the target of the night noise guideline to protect the public, including the most vulnerable groups such as children, the chronically ill and the elderly," with 55 dB offered only as an interim target where 40 cannot be achieved in the short term. The U.S. EPA's 1974 levels document identified 55 decibels outdoors and 45 indoors, as a day-night average, as the levels that prevent activity interference and annoyance, and a 24-hour average of 70 as the level that prevents measurable hearing loss over a lifetime. The National Institute on Deafness and Other Communication Disorders puts normal conversation at 60 to 70 dBA and says long or repeated exposure at or above 85 dBA can cause hearing loss.

Set those against the readings in the complaints. Southaven residents report more than 70 dBA at their property lines from the turbine fleet, which is conversation volume at the fence, all night, and above the city's one remaining ceiling. The Vineland, New Jersey plaintiffs measured 48 to 60 dBA against a 50 decibel overnight standard. Dowagiac residents describe 50 to 62 decibels at all hours. Every one of those nighttime figures is above the WHO target, and most are above the 55 dBA nighttime limit that Prince William, Fairfax, and the City of Frederick use. A 55 dBA ordinance is already 15 decibels above the WHO night target; because decibels are logarithmic, that is a large multiple of the sound energy, not a rounding error.

What a chiller yard or a turbine produces at its source is a separate question, and we are not publishing equipment source levels here because we could not verify a manufacturer specification sheet this cycle. The ordinances themselves tell you what to listen for. Prince William's definition of steady tonal sound names the sources: "heating, ventilating or air-conditioning units, refrigeration units, transformers, and backup generators."

The ordinances above also tell you how the county would measure, and matching that method is what makes a resident's reading defensible. The pattern across the Virginia codes is consistent.

• Measure where the code says. Prince William, Fairfax, and Culpeper all measure at the property boundary of the source or at any point within the affected property. Loudoun measures at the point on the receiving lot line closest to the source. Mount Pleasant measures outside the boundary of the emitting property. Stand where the ordinance stands, and write down exactly where that was.
• Use a real meter. Prince William defines a sound level meter as one meeting Type 1 or Type 2 performance under ANSI S1.4 or IEC 61672, checked with a calibrator conforming to ANSI S1.40 or IEC 60942. Culpeper requires Type 2 or better. A phone app is fine for deciding whether to buy a meter; it is not what an ordinance contemplates, and an opposing expert will say so.
• Record A and C, and the difference. Take each reading in dBA and dBC. A gap of more than about 15 dB between them is the signature of low frequency content, and in Prince William the dBC number is now independently enforceable against the 73 and 68 limits. Set the meter to slow response for steady sound, which is what both Fairfax and Prince William specify.
• Sample the way the code samples. Prince William's Table 1 is an Leq limit that is violated when exceeded in three or more intervals of at least 30 seconds within an hour; the dBC limit is a five-minute interval. A single peak proves less than a logged hour. Log the ambient level too, ideally when the facility is quiet, because the codes define the source level as total minus ambient.
• Time stamp everything and cover nights. Every numeric code in the table drops its limit at 10 p.m. Readings between 10 p.m. and 7 a.m., logged over multiple nights and tied to weather and wind, are the ones that matter. Put the date, time, location, meter model, calibration check, and weighting on every entry.

Our evidence guide covers the full file, including the complaint paper trail with the county, which matters because Loudoun's zoning enforcement division, Prince William's police chief, and Southaven's police chief are each the designated measuring authority under their codes. Ask them, in writing, to measure. Their reading, or their refusal, goes in the record.

A noise lawsuit without an ordinance is an argument about reasonableness: was this sound a substantial and unreasonable interference with the use of a home? A noise lawsuit with a violated ordinance is an argument about a number. The Southaven plaintiffs understood this, which is why Haley v. xAI pleads negligence per se alongside private nuisance and public nuisance. Negligence per se treats a violation of a safety ordinance as the breach itself; the residents' readings above 70 dBA, set against the city's 70 dBA property-line ceiling, do the work that expert testimony about reasonableness would otherwise have to do.

An exceedance also carries its own enforcement weight, which creates leverage before any suit. Prince William treats a violation as a Class 4 misdemeanor, a Class 3 on repeat within a year, or a civil penalty of $250 then $500, though the civil penalty route does not apply to noise from business on industrial property. Southaven's penalty is up to $1,000 and 90 days, and "a continuation of a violation shall constitute a separate offense each day." Dowagiac, per reporting on our tracker, actually fined the operator before the class action was filed. A citation is an admission the county has already made on your behalf.

The reverse is not true: compliance is not a defense to everything. Culpeper County wrote that principle into its code. Sec. 10A-6(b) provides that nothing in the chapter "is intended to preclude actions to abate or enjoin nuisances," and that official enforcement "shall not be a precondition to the bringing of an action." A facility under 55 dBA that keeps a neighborhood awake with a 65 dBC hum has not violated Loudoun's ordinance, and it can still be a nuisance. The Great Oak dispute in Prince William shows the middle path: documented likely exceedances of the 60 dBA daytime limit, no lawsuit, and roughly 10 decibels of engineering mitigation from Amazon under county pressure.

Half the rows in our table have no decibel figure. Memphis and Shelby County prohibit "unreasonably loud, disturbing and unnecessary noise." Newton County uses audibility at 75 feet; Social Circle uses 100 feet. Racine County, outside the Village of Mount Pleasant, uses a reasonableness standard with no number. Unincorporated Hood County, Texas has no local noise code we could locate, and the Texas Penal Code's 85 decibel presumption is a criminal disorderly conduct standard aimed at people, not a property-line limit for industrial plants.

None of that ends a case. The Granbury lawsuits against Marathon Digital were built on migraines, tinnitus, and sleep loss documented across dozens of households, with no ordinance to point to, because nuisance law asks whether the interference is substantial and unreasonable, not whether a code was broken. The audibility standards are also more useful than they look: a data center hum that is plainly audible at 100 feet is, in Social Circle, a violation on its face, and "plainly audible" is something a neighbor can testify to without a meter. And the general "unreasonably loud" codes still give you a complaint number to call and a record of the county's response.

The practical sequence is the same everywhere. Find your row in the table, or pull your own code if your county is not on it. Measure the way the code measures, A and C weighted, at night, over weeks. File written complaints with the enforcement authority the code names and keep the responses. Compare your readings to the operator's own studies where a jurisdiction requires them. Then talk to a lawyer about whether the facts support nuisance, negligence, or negligence per se in your state. Our free case review connects you with an independent attorney in our network who handles data center cases in your state, at no cost and with no obligation. The table tells you the number. The log is what proves it.