Are Data Centers Loud? Data Center Noise, Decibel Limits and Rules

Where the noise comes from

Loudoun County, in Northern Virginia, the world's largest data center market[4], says the noise comes from the machinery that keeps a facility running, including cooling and mechanical systems[1], HVAC units and emergency backup generators[1]. Most data centers there run their diesel generators for one hour a week for mandatory testing[1].

Why the hum bothers people

It is often the kind of sound, not the volume. Loudoun County says complaints frequently concern tonal noise, and that a single-frequency tone can be more aggravating than background noise at a similar volume[1]. Loudoun has historically regulated noise with A-weighted decibels (dBA), which focus on the frequencies people hear best[1], and says it has no rules specific to tonal or low-frequency noise and that measuring it well takes other metrics such as C-weighted (dBC) readings[1].

In Prince William County, one Great Oak resident told the Prince William Times his 7-year-old wakes up thinking there is a spaceship outside[5]. An Amazon Web Services representative wrote that its recent sound study shows its efforts have significantly reduced sound[5].

What the evidence says

Virginia's Joint Legislative Audit and Review Commission found data centers emit low-frequency noise that is not loud enough to damage nearby residents' hearing and is rarely loud enough to violate noise ordinances[3]. A large majority of data centers draw no complaints because of their location or design, but their constant noise has sometimes been a problem near homes[3]. JLARC noted local ordinances usually target short, loud noises and carry a maximum civil penalty of $500[3], and suggested letting localities set data center sound limits, including low-frequency measures[3].

Decibel limits and noise rules

Loudoun County, Va.: 55 dBA maximum at residential property lines[1], with required noise studies before construction and one to 12 months after opening[1].
Prince William County, Va.: an ordinance adopted in October 2025 limits noise in industrial areas to 73 decibels by day and 68 at night[6]; a stricter expert-drafted version was not adopted[6].
Fairfax County, Va.: buildings at least 200 feet from residential lot lines, generators 300 feet away or shielded, equipment enclosed or screened, and noise studies before and after construction[7].
Virginia (state law): for facilities needing 100 MW or more, localities must require a sound assessment covering homes and schools within 500 feet before approval[2].
Chandler, Ariz.: annual noise studies at peak operation for five years after construction[8].

See every rule we track in the local data center rules tracker.

What the Census record shows

In the Census, residents raised noise as an issue for 47 projects, and 9 records document how close the nearest homes or schools are. Check projects near you.

Common questions

Are data centers loud?

Usually not loud enough to damage hearing or violate noise ordinances, according to Virginia’s legislative auditors, but the constant low-frequency hum has been a problem for some nearby homes.

How many decibels is a data center?

It depends on the site and distance. Localities set limits at property lines: Loudoun County, Virginia, caps sound at 55 dBA at residential property lines, and Prince William County limits industrial areas to 73 decibels by day and 68 at night.

Why do data centers hum?

Cooling equipment, HVAC units and backup generators create a constant, often tonal, low-frequency sound. Loudoun County says a single-frequency tone can be more aggravating than background noise at a similar volume.

Sources

Data Centers: Noise & Air Quality Concerns
Loudoun County, Virginia · 2026
10 source excerpts
“For residential properties, the maximum allowable sound level at the property line is 55 dBA.”
“The majority of data centers in Loudoun County run their backup diesel generators for one hour, once per week, for mandatory testing”
“Noise complaints, which residents may submit online, are among the most persistent issues brought forward to Loudoun County officials and frequently pertain to tonal noise.”
“These include the basic machinery that keeps a data center up and running, including lighting, cooling, mechanical systems and the electricity needed to run them.”
“Noise also emanates from HVAC units and emergency backup generators.”
“Broadly known as tonal noise, single frequency tones can be more aggravating to the human ear than broadband background noise at similar volumes.”
“Loudoun County and many other localities have historically used decibel-based A-weighted sound measurement standards to regulate noise (dBA) because dBA measurements focus on the noise frequencies most audible to humans.”
“The county does not currently have policy or regulatory language specific to tonal noise or low frequency noise.”
“The most effective approaches to measuring and regulating such noise use multiple measurement types, such as octave band and C-Weighted decibel measures (dBC), which some localities utilize to better monitor and control noise across a range of frequencies.”
“Per the Loudoun County Zoning Ordinance, data centers are required to submit a pre-construction noise study at the time of site plan review as well as a post-construction noise study submitted at least one month but no more than 12 months after the issuance of the first Certificate of Occupancy.”
Code of Virginia § 15.2-2209.5 (High energy use facilities; site assessment)
Virginia General Assembly (Virginia Law Library) · 2026
Source excerpt
“Prior to any approval of a rezoning application, special exception, or special use permit for the siting of a new HEUF, a locality shall require that an applicant perform and submit a site assessment to examine, to the extent practicable and within the timeline provided by subdivision A 7 of § 15.2-2286, the sound profile of the HEUF on residential units and schools located within 500 feet of the HEUF property boundary.”
Data Centers in Virginia (Report 598)
Joint Legislative Audit and Review Commission (JLARC), Virginia General Assembly · 2024-12
5 source excerpts
“Data centers emit low-frequency noise that is not loud enough to damage nearby residents' hearing and rarely loud enough to violate noise ordinances.”
“The constant nature of data center noise has sometimes been a problem when data centers are located near residential areas.”
“Although noise has been a problem for some data centers, a large majority of data centers do not generate noise complaints because of their location or design.”
“Localities traditionally use noise ordinances to address noise concerns, but those typically target excessively loud noise from short-term sources, such as parties and barking dogs, and carry a low maximum civil penalty of $500.”
“The General Assembly may wish to consider amending the Code of Virginia to expressly authorize local governments to establish and enforce maximum allowable sound levels for data center facilities, including (i) using alternative low frequency noise metrics”
Data Centers in Virginia (Report 598, Summary)
Joint Legislative Audit and Review Commission, Commonwealth of Virginia · 2024
Source excerpt
“Northern Virginia is the largest data center market in the world, constituting 13 percent of all reported data center operational capacity globally and 25 percent of capacity in the Americas.”
Coming crackdown on data center noise likely won't bring relief to a community most affected
Prince William Times · 2025-03-06
2 source excerpts
“"My 7-year-old wakes up and says he thinks there is a spaceship outside our house," said Carlos Yanes.”
“"The data in our recently completed sound study demonstrates that (Amazon Web Services') efforts have significantly reduced sound," wrote Sarah Georgiades.”
Supervisors OK compromise noise ordinance aimed at data centers
Prince William Times · 2025-10-30
2 source excerpts
“It limits daytime noise in industrial areas to 73 decibels during the day and 68 at night.”
“Among other things, it would have reduced acceptable noise limits in industrial areas from 79 to 67 decibels during the day and from 72 to 62 decibels at night.”
Board of Supervisors Approves New Data Center Zoning Ordinance Amendment
Fairfax County Government News Center · 2024-09-10
4 source excerpts
“Data center buildings must be at least 200 feet from the lot line of an adjacent or abutting residential district or property.”
“Equipment such as back-up generators must be 300 feet from the lot line of residential property or separated from the lot line of a residential district or residential property by the data center building.”
“In all districts where data centers are allowed, all equipment must be enclosed or screened by a wall or similar barrier to reduce visual and noise impacts.”
“Pre- and post-construction noise studies must be submitted to ensure compliance with the Noise Ordinance.”
Chandler's data center ordinance now in effect
City of Chandler, Arizona · 2023-01-11
Source excerpt
“Requires the data center to conduct an annual noise study during peak operation times for five years once construction of the data center is complete”

Each source was opened and checked against the excerpt shown. Company statements are identified as such. Figures are as published; where sources differ, each is shown.