A Case Study of Acoustic Design in a Commercial Complex

 

 

Project Overview

The seventh-floor roof of a certain shopping mall serves as the installation area for noise source equipment.

 

The seventh-floor roof have the cooling towers, fans, air-cooled heat pumps and other equipment with noise source, and on the sixth floor roof have the outdoor air processors, Range Hoods, and outdoor units of air conditioner.

 

Located 45m from residential buildings, roof noise source of equipment can have a negative impact on the residential building's acoustic environment.

 

Design Principles

Strict adherence to relevant environmental protection regulations; noise control considerations prioritize ensuring that all post-treatment indicators meet environmental protection requirements.

 

Strive to preserve and utilize existing equipment, structures, and other resources without compromising normal working conditions and equipment maintenance; in compliance with safety, fire, and other relevant regulations.

 

Considering the specific circumstances and characteristics of this project, adopt mature and reliable processing techniques, balancing practicality and innovation, with a primary focus on practical reliability.

 

Materials should be aesthetically designed, easy to maintain, ensuring noise reduction effectiveness while minimizing the footprint.

 

Control Goals

After the completion of the noise control for all roof noise sources, the noise value at the parapet wall around the roof meets the Class II standard requirements of GB 3096-2008 "Environment Quality Standard for Noise." That is, the daytime (6:00-22:00) noise value is ≤60 dB(A).

 

 

Nighttime (22:00~next day 6:00) commercial roof equipment is not operational, and nighttime standard requirements are temporarily not considered. If influenced by background noise, adjustments will be made according to national standards.

Solution

The methods are categorized into traditional passive treatment methods and active treatment methods.

 

The passive treatment methods include two approaches:

 

The first is noise source control, with measures involving the muting modification of the cooling tower, including the outlet and water-spraying area.

 

The second approach is noise propagation path control, with measures employing acoustic hoods or sound barriers to isolate or shield direct sound along the propagation path.

 

This case mainly provides an engineering solution from the perspective of noise propagation path control.

 

 

Design Scheme

Design Scheme for Cooling Tower Equipment

 

Design the installation of metal sound barriers between the cooling tower water pipes and the wind well, with double doors placed at appropriate locations.

 

Install an intake muffler at the bottom of the sound barrier.

 

The height of the sound barrier is designed to be 7.5m, and the bottom muffler height is 1.5m.

 

The depth of the muffler is 400mm, and the acoustic splitter features a "V"-shaped structure.

 

The sound deadening capacity of the muffler is greater than 15dB(A), with a through-flow ratio exceeding 50%.

 

 

 

Design Scheme for Air-cooled Heat Pump

 

Install an outlet muffler at the air-cooled heat pump outlet, with a buffer zone between the acoustic splitter and the outlet.

 

Around the compressor of the air-cooled heat pump, install a convenient detachable low-frequency sound absorption module.

 

Externally install a acoustic hood for the air-cooled heat pump, with an intake muffler at the bottom of the acoustic hood.

 

Maintain sufficient spacing between the acoustic hood and the equipment, leaving a acoustic door for easy personnel access for inspection.

 

 

 

Post-Treatment Effect

 

Noise value at the parapet wall is ≤60dB(A).