Is a Data Center Coming

Guides

How loud is a data center? Noise, distance and what to ask for

Published September 6, 2026

A data center is not one loud thing. It is a lot of quiet-to-moderate things running at the same time, all day, every day, for years. The steady sound is cooling: rooftop and ground-level fan units and chillers that run continuously to keep the servers from overheating, loudest on hot afternoons and evenings when the equipment works hardest. Layered on top of that is intermittent noise from backup diesel generators, which most campuses run for a scheduled test, typically once a week or once a month, for 30 minutes to an hour, and it is much louder while it lasts than the constant hum underneath it.

What gets measured, and what does not

Local noise rules almost always measure in A-weighted decibels, dBA, at the property line of the nearest home. Loudoun County, Virginia, the county with the most data centers built and the most complaints on record, caps residential property-line noise at 55 dBA under its current zoning ordinance, with no separate nighttime limit. The county's own review of the standard has acknowledged a real gap: dBA measurements do not capture the low-frequency tonal hum that residents near existing campuses describe as the most disruptive part, since a steady hum can meet a decibel limit and still be what people notice most.

Other jurisdictions have gone further by splitting day and night. Prince William County, Virginia, limits residential noise to 60 dBA in the day and 55 at night. The town of Warrenton, Virginia, allows up to 62 dBA in the day and 57 at night. Niagara Falls, New York, capped data centers at 50 dBA in the day and 45 at night and confined new noise-generating facilities to industrial and business park zones. For comparison, ordinary conversation runs 55 to 65 dBA, so a facility sitting right at one of these limits is, on paper, no louder than people talking. Residents near an operating Loudoun County campus have still filed a steady stream of noise complaints even where measured levels fall inside the legal limit, which is the low-frequency-hum problem again: the same decibel number sounds very different depending on whether it is broadband noise or a narrow, steady tone.

Chandler, Arizona took a different approach entirely. Its ordinance, in effect since January 2023, does not set a single decibel ceiling. Instead it requires a third-party acoustic engineer to measure the existing background sound at the property line before construction starts, and then requires that the completed facility not push noise above that pre-construction baseline, checked again every year for five years after the facility opens. That shifts the standard from "quieter than an arbitrary number" to "no louder than it already was here," which is a meaningfully different promise to residents.

How sound falls off with distance

For a compact source in open air, sound pressure drops by about 6 dB every time the distance from it doubles. That is a real acoustic rule, not a rough guess, though large campuses with many separate fan units and generators fall off somewhat more slowly at close range than a single point source would, since you are not always doubling your distance from every piece of equipment at once. Take a campus that measures 65 dBA at a house 500 feet from its fans. At a quarter mile that same sound is around 57, at half a mile around 51, and at a mile around 45, before counting tree cover, berms or buildings in between, which all help. So a resident half a mile from the fence and a resident a mile away are not hearing close to the same thing. Distance is doing most of the work.

What a good noise condition says

The conditions attached at approval are what residents actually live with, since they are very hard to add or tighten after a project is built. A condition worth asking for at a rezoning hearing should specify, in writing: a dBA limit measured at the affected property line, not just somewhere on the site; a separate, lower nighttime limit, since a daytime-only cap leaves nights uncovered; specific hours for generator testing, typically weekday daytime only, so tests are not sprung on people trying to sleep; and, ideally, a baseline or tonal-noise standard like Chandler's rather than a flat dBA number alone, since a flat number is exactly what has not stopped complaints in counties that already have one.

At the hearing itself, the practical questions are: where will the pre-construction baseline be measured and by whom, what happens if a post-construction measurement exceeds it, who enforces that, and what is the generator testing schedule. Ask for the answers in the written conditions, not a verbal assurance, since only the written conditions survive after the vote.

If you want to know what is tracked near a specific address, check it here, or read the fuller guide to living near a data center, which covers outages, water and your power bill as well as noise.

Sources