In the next few weeks, City Council is expected to revisit the upper limit of permitted noise from mechanical units such as air conditioning and HVAC units placed outside homes or buildings.

A 2013 amendment to the International Mechanical Code, which City Council adopted earlier, doubled the allowable decibel level allowed for mechanical equipment, such as air conditioning and HVAC units, said Community Development Director Mark Muenzer at the Dec. 12 meeting of the City Council’s Administration and Public Works Committee meeting. The previous level was 55 decibels, and in 2013 the Council increased the allowable level to 65 decibels.

For residential areas, the U.S. Environmental Protection Agency has identified 55 decibels as the maximum level of outdoor environmental noise to protect public health and welfare and not interfere with outdoor activities or damage hearing, according to a memo from Mr. Muenzer and Gary Gerdes, the City’s Building & Inspection Services Division Manager.

“Staff recommends that we revert to 55 decibels,” Mr. Muenzer told the committee members. “Throughout the City, the general ambient noise is 48-52 decibels.” He said recent complaints by residents in the vicinity of a multifamily complex where a new condensing unit has been installed prompted staff to revisit the 2013 ordinance. Most air-conditioning equipment operates at levels of 73-78 decibels, according to the memo, and ambient noise measured at residential properties near the complex mentioned in the complaints has been measured at 48-52 decibels.

Quieter options for air-conditioning units and other mechanicals are available, said Mr. Muenzer: installing landscape barriers, moving the units farther away from neighbors – such as to the rear of the property – or installing “quiet packs,” which reduce blade noise.

“Staff believes noise levels meeting EPA-established health and safety levels should take precedence over enforcement concerns,” the memo said. It also recommended putting the onus on the owner/installer to use one of these options.

Several cities – Chicago, Seattle, Denver, Los Angeles, and Washington, D.C. – have set maximum decibel levels at 55. Some of these allow 55 between 7 a.m. and 10 p.m. and reduce the level to 50 or 45 at night.

“I think we should move forward immediately,” said Third Ward Alderman Melissa Wynne. “I think that doubling the amount of noise was never on our minds.”

Mr. Muenzer and Mr. Gerdes said they would return in the first quarter of next year with a proposed amendment to the International Mechanical Code, which would apply only to new or replacement installations on multifamily units and in commercial and industrial locations. To make new levels applicable to single-family residences would require an amendment to the International Residential Code, which the City has also adopted.

Decibel Levels of Some Common Noises

A memo from Community Development Director Mark Muenzer and Gary Gerdes, the City’s Building & Inspection Services Division Manager, provided information on the sound levels of typical environmental noises. Some examples follow.• Physically painful: sonic boom, 140 decibels• Discomforting: whistle at 1 meter’s distance, 120 decibels• Very annoying: siren at 10 meters (110 decibels); chainsaw at 1 meter (105 decibels)• Very loud: jackhammer at 10 meters (100 decibels); loud crying (95 decibels); passing car at 7.5 meters (75 decibels)• Intrusive: noisy lawnmower at 10 meters (75 decibels); low volume of radio or TV at 1 meter (55 decibels)• Quiet: refrigerator at 1 meter (50 decibels); bird twitter outside at 15 meters (50 decibels)• Very quiet: soft whisper at 4.5 meters (30 decibels)