Huntsville, AL Noise from Specific Sources: HVAC & Mechanical Noise (2026)

Section 12-265(a) does not single out air conditioners, but it covers them because it applies to any source of sound, and the limit is set by the land that receives the noise rather than the lot the unit sits on. A condenser on a commercial lot that is heard at a neighboring house is judged against the residential number: 55 dB(A) from 7:00 a.m. to 10:00 p.m. and 50 dB(A) from 10:00 p.m. to 7:00 a.m. Commercial or business receivers get 62 dB(A) at all times and industrial receivers get 70 dB(A) at all times. When a source can be identified and measured in more than one land use category, the most restrictive category controls. Under section 12-231, land use category means the actual existing use of the land regardless of its zoning designation.

Readings follow section 12-264. The meter is set to the A-weighted network and slow response, and it is calibrated before and after each use. Measurements are taken at the approximate property line, at least four feet above the surrounding surface, and only when ambient sound is at least ten dB(A) lower than the unit being measured. The recorded figure is the highest level with the source running. Separately, no source may exceed 86 dB(A) measured 25 feet or more away. Section 12-235 requires a type 1, 2 or S2A meter and a coupler-type calibrator accurate to within 0.5 dB, and section 12-236 requires trained operators.

Enforcement belongs to the noise control officer, who is the director of the city's air pollution control office, and to sworn peace officers (section 12-263). The officer can swear out an affidavit before a municipal court magistrate to obtain a summons on probable cause, or serve as a witness for a resident who wants to do that personally.

Section 12-262 exempts bells, emergency sirens, permitted temporary events, construction equipment in daytime hours, emergency work and a few other sources. Heating and cooling equipment is not on that list. The one nearby exemption, item (13), covers noise sources inside multifamily dwellings, office and apartment complexes and condominiums that affect only people within the same dwelling, complex or building. Domestic power equipment is a defined term limited to equipment rated at 15 horsepower or less for home or building repairs and grounds maintenance, with its own 80 dB(A) cap at 25 feet in daytime hours.