Acoustic Enclosure for Rooftop Chillers at Fabrik1230

Project Overview

Modern rooftops often carry the pulse of the city, mechanical chillers, condensers, and ventilation systems that ensure comfort within the buildings below.

At Fabrik1230 in Vienna’s 23rd district, this mechanical heartbeat risked disturbing nearby offices and residences. The challenge was to preserve the project’s architectural integrity and energy efficiency without compromising acoustic comfort.

DECIBEL’s engineering team stepped in to transform a noisy necessity into a silent achievement above the skyline.

Challenge

The installation of two large THEATU 4450 air-cooled chillers on the rooftop created significant mechanical noise, particularly low-frequency resonance and tonal peaks.

Initial plans for a three-wall enclosure left the system open to sound leakage and insufficient noise reduction.

The project required a complete rethink to achieve measurable silence while maintaining airflow, access, and structural stability.

Scope of Work

• Acoustic simulation and performance modelling
• Redesign of the original enclosure concept
• Fabrication and installation of a fully enclosed acoustic structure
• Integration of ventilation attenuators and acoustic louvres
• On-site performance testing and verification

Solution

DECIBEL developed a fully enclosed acoustic system engineered to contain and diffuse sound energy while preserving cooling efficiency.

The design incorporated 100 mm PZP acoustic panels with dense mineral wool cores, 600 mm exhaust attenuators with splitter elements, and DECIBEL AL 300 acoustic louvres at intake and exhaust points.

Using 3D particle-based simulations, the team optimised panel densities, perforation ratios, and louvre spacing before fabrication. Each prefabricated module was craned into position with millimetre precision, ensuring acoustic continuity across all seams and joints.

Result

Post-installation measurements confirmed an average reduction of 15.8 dB(A), exceeding design expectations. A mid-range compressor reduced low-frequency hum by up to 14 dB and virtually eliminated high-frequency reflections.

The outcome is a rooftop enclosure that blends function and form, silent, efficient, and discreet. You can read the full case study for more details here. 

Across Europe’s urban centres, rooftop HVAC systems are among the fastest-growing sources of environmental noise. The Fabrik1230 project demonstrates how data-driven design, predictive simulation, and precision engineering can eliminate this challenge. Get in touch with DECIBEL to explore professional soundproofing and acoustic solutions tailored to your needs.