1. Project Overview & Background
Hohhot MixC is a premier large-scale commercial complex. Multiple commercial cooling tower units are centralized on the rooftop to meet the intensive HVAC cooling loads of the mall. During operation, the cumulative aerodynamic noise from cooling tower fans and the splashing sound from water distribution systems generated significant environmental noise, posing acoustic disturbance concerns for adjacent high-rise residential buildings and the surrounding commercial area.
2.Noise Source Analysis & Project Challenges
Primary Noise Sources:
l Fan Aerodynamic Noise: Medium-to-low frequency noise produced by high-speed fan rotation, characterized by strong penetration and long-distance propagation.
l Water Splashing Noise: High-frequency impact noise generated by falling cooling water striking the internal fill packing.
l Vibration Radiation Noise: Secondary structure-borne noise radiated from operating mechanical components and supporting piping.
3.System Design & Engineering Solution
The engineering solution integrates three core modules tailored for severe climatic conditions and strict acoustic targets:
3.1 Acoustic Louvers (Soundproof Ventilation Louvers)
The enclosure features modular blade-type sound-absorbing acoustic louvers. Each louver blade is filled with high-density hydrophobic mineral wool lined with acoustic fabric and protected by perforated sheet metal. Air passes freely through the louver passages to maintain equipment intake volume, while sound waves are absorbed and attenuated as they traverse the internal acoustic baffles. The external facade provides a clean, modern aesthetic that covers cluttered rooftop machinery.
3.2 Hot-Dip Galvanized Structural Steel Substructure
An independent structural steel framework was erected on the roof to anchor the acoustic louvers. Designed with non-penetrating footings to protect existing roof waterproofing, the framework incorporates dedicated maintenance access doors and walkways for ongoing HVAC servicing.
3.3 Key Technical & Performance Specifications
Design Parameter / Module | Engineering Specification & Feature |
Acoustic Performance | Single-layer acoustic louvers deliver sound attenuation of 15–22 dB(A), ensuring strict compliance with boundary environmental noise standards. |
Corrosion & Weathering Resistance | Hot-dip galvanizing combined with electrostatically powder-coated finish provides long-term protection against frost, sandstorms, and UV exposure. |
Airflow & Aerodynamic Optimization | Louver free area (open area ratio) and static pressure loss were verified via CFD fluid dynamics simulations to prevent cooling efficiency loss. |
Facade Aesthetics & Finish | Coated in dark grey powder finish matching the commercial complex exterior architectural tone for visual integration. |
4. Project Outcomes & Benefits
l ✅ Noise Mitigation Compliance: Radiated noise levels from rooftop cooling towers were significantly reduced, meeting regional environmental noise emission standards and eliminating noise complaint risks from adjacent properties.
l ✅ Uncompromised HVAC Efficiency: Calculated airflow aperture guaranteed required intake volume, maintaining optimal chiller condensation temperatures and refrigeration performance during peak summer loads.
l ✅ Enhanced Commercial Aesthetics: Unslightly rooftop mechanical units are fully concealed behind a sleek, uniform architectural louver screen, elevating the mall roof profile.
l ✅ Long-term Harsh Climate Durability: Dual protection (hot-dip galvanizing + weatherproof powder coating) withstands northern freeze-thaw cycles and sandstorm erosion, extending maintenance cycles.
✅ Streamlined Maintenance Access: Integrated steel walkways and acoustic access doors ensure effortless routine inspection, cleaning, and maintenance for facility engineer.
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