What will neighbors hear, especially at night?
Ask what noise limits apply at nearby homes and who checks the finished site.
If you live near the site, ask what you will hear, especially at night. Fans, cooling equipment and generators can make different sounds. A steady low hum needs attention, and so does the loudest event.
A steady sound can reach homes below the legal limit and still be heard all night.
Cooling fans and other equipment make a steady sound. Sound fades as it spreads. As a rule of thumb, one small source in open space drops 6 decibels each time the distance doubles.
A real site has many machines, walls and uneven ground. The rule of thumb does not give real levels there. The usual meter setting (“dBA”) counts a low hum less. Ask if the sound study also covers low-pitched sound.
At a home, the meter can read below the legal limit while the sound goes on all night.
Sources: Federal Highway Administration, Highway Traffic Noise: Analysis and Abatement Guidance, “Noise Fundamentals”, August 24, 2017; Virginia Joint Legislative Audit and Review Commission (JLARC), Data Centers in Virginia (Report 598), December 9, 2024; Federal Aviation Administration, Fundamentals of Noise and Sound, March 29, 2022; Microsoft (Microsoft Local), Update on our investigation of humming sound at our Mount Pleasant datacenter, July 20, 2026.
What good looks like
- A study covers nearby homes, running at night and generator testing.
- Adopted limits say where, when and how sound is measured.
- After the site is built, measurements and a complaint process check the predictions.
What to watch for
- The only evidence is a promise to be quiet.
- A limit on construction hours is offered as the operating noise limit.
- A study leaves out nearby homes, equipment running together, or steady tonal sound.
Where to look
- Acoustic study and site plan The sound study, and the drawing of what will be built where.
- Local noise rule or approval conditions The local law on noise, or the conditions written into the approval.
- Post-construction sound measurements and complaint findings Sound readings taken after the site is built, and the findings on complaints.
In Virginia, data center noise that drew complaints was an estimated 40 to 59 decibels. That was typically below the local limit of 55 or 60.
Noise that drew complaints (estimated)
40 to 59 decibels
Local limit near homes
55 or 60 decibels
Measured result
Source: Virginia Joint Legislative Audit and Review Commission (JLARC), Data Centers in Virginia (Report 598), December 9, 2024.
The trade-off
Distance, the layout of equipment and sound barriers can help. A limit or a model still has to be checked against how the site actually runs.
Does an adopted rule or approval set a noise limit, as a number, for the site when it runs?
- Yes
- The adopted rule that applies sets a limit as a number. Write down its units, where it is measured, the time period and any exceptions.
- No
- The authority in charge confirms outright that no such limit applies to the site.
- Not known
- You found only construction hours, a draft study, general promises, or a rule you could not verify.
Two real projects
Lighthouse — Port Washington
Port Washington, Wisconsin
Do the listed records show enforceable noise limits, as numbers, for the site when it runs?
Not knownOfficial record
The city adopted limits on outdoor construction hours, starting on April 18, 2026. These are conditions on construction. They are not sound limits, stated as a number, for the site in operation. The listed records do not show limits of that kind.
Source: City of Port Washington, City amendment of construction hours and project financing update, March 19, 2026.
Microsoft Fairwater 1 — Mount Pleasant
Mount Pleasant, Wisconsin
Do the listed records show enforceable noise limits, as numbers, for the site when it runs?
Not knownCompany statement
On April 15, 2026, Microsoft said the site’s noise levels “meet the requirements set by local ordinance” (a local law). Its updates do not name that law or give its limits as numbers. On June 18, 2026, Microsoft said its “independent monitoring” showed that its steps to reduce the sound had “fully resolved the issue”. The updates give no measured sound levels. On July 20, 2026, Microsoft said it was still working on short-term steps to reduce the sound.
Source: Microsoft, Mount Pleasant sound investigation update, July 20, 2026.