Continuous low-frequency noise from cooling plant reaches homes at levels ordinances are not written to measure
#00205
data-center chillers and fans emit steady tonal and low-frequency sound. Ordinances measure broadband dB(A), which misses the 90 Hz-range tones residents report, so a facility can be simultaneously compliant and intolerable. Modelled buildout reached 77 dB(A) 180 feet from homes.
#00216Retrofit operating cooling plant with attenuators, enclosures and low-tonality fans
Fit fan mufflers, acoustic shrouds, inlet and exhaust enclosures and lower-speed fans to plant already causing complaints. Documented at CyrusOne in Chandler, Vantage in Sterling, Amazon in Northern Virginia and Microsoft's Mount Pleasant site. No operator publishes the cost.
#00215Write noise limits in octave bands and dBC, measured at the residential property line, as a permit condition
Replace single-number dB(A) ordinances with limits that also constrain C-weighted and per-octave-band levels at the nearest residence, set as a permit condition rather than a complaint threshold. Prince William County proposed exactly this after observing a 90 Hz tone at a specif