Acoustic Louver
Outdoor Air Louvers with Noise Reduction for Fresh Air and Exhaust Air Openings
Acoustic Louver is a special outdoor air louver used at fresh air intake and exhaust air openings in HVAC systems. It helps reduce airborne noise while limiting the entry of rain, leaves and birds.
Its sound-absorbing blade structure, aerodynamic form and perforated metal protection for the absorption material make it suitable for façade and ventilation applications where air passage and acoustic comfort must be considered together.
Acoustic Noise Reduction
Sound-absorbing blades help reduce airborne noise at outdoor air openings.
Outdoor Protection
Protects air handling units and ventilation systems against rain, leaves and bird entry.
Single / Double Row Option
A single-row louver can be selected for standard acoustic needs, while a double-row louver is available for demanding requirements.
What Is an Acoustic Louver?
An acoustic louver is a special louver type installed on a façade or air duct opening that allows airflow while contributing to sound absorption. Unlike standard outdoor air louvers, its blades contain sound-absorbing material.
This construction is used for fresh air intakes, exhaust air discharge openings, generator rooms, technical spaces, mechanical room ventilation and applications requiring noise control on the building façade.
Acoustic Louver Operating Principle
Air Passage
Fresh air or exhaust air passes between the aerodynamic louver blades.
Sound Absorption
The absorption material inside the blades contributes to reducing airborne noise.
Protection from Outdoor Elements
Closely spaced blades and bird mesh limit the entry of rain, leaves and birds.
Low Pressure Drop
The aerodynamic blade form helps keep the differential pressure under control during airflow.
Key Technical Features
Acoustic outdoor air louver for fresh air and exhaust air openings.
NL single acoustic louver, NL-H double-row high-performance louver, NL-D inactive section.
Galvanized steel sheet or aluminium body and blade construction.
Aerodynamic blade structure with 150 mm blade spacing.
12 × 12 × 1 mm galvanized steel bird mesh.
Standard construction, powder coating or anodized surface option.
Acoustic Louver Technical Information Table
| Technical Item | Value / Description |
|---|---|
| Product type | Acoustic outdoor air louver |
| Application area | Fresh air intake and exhaust air discharge openings |
| Maximum single-piece size | 1800 mm width × 2250 mm height |
| Multi-section width | Combined construction across widths of up to 3600 mm |
| Multi-section height | Combined construction across heights of up to 4500 mm |
| Recommended face velocity | Maximum 2 – 2.5 m/s for fresh air openings |
| Airflow range | 666 – 24,372 m³/h at 1.75 m/s, for single-piece construction |
| Differential pressure | Approximately 25 – 75 Pa for fresh air and 30 – 100 Pa for exhaust air at 1.75 m/s |
| Absorption material | Mineral wool faced with glass fibre fabric and protected by perforated metal sheet |
| Test standard | Sound power level and airborne noise absorption have been tested according to ISO 7235. |
Acoustic Louver Types
| Type | Description | Application Note |
|---|---|---|
| NL | Standard single acoustic louver | Used for fresh air and exhaust air openings with normal acoustic requirements. |
| NL-H | High-performance double-row acoustic louver | Preferred for demanding acoustic requirements and applications requiring higher sound insulation. |
| NL-D | Inactive section without acoustic function | Can be used with active louver sections to provide a uniform façade appearance. |
Acoustic Performance Table
The values below are based on sound attenuation and sound insulation performance at the listed centre frequencies.
| Performance Item | Type | 63 Hz | 125 Hz | 250 Hz | 500 Hz | 1000 Hz | 2000 Hz | 4000 Hz | 8000 Hz / Rw |
|---|---|---|---|---|---|---|---|---|---|
| Sound attenuation De, dB | NL | 3 | 4 | 7 | 8 | 13 | 15 | 13 | 15 |
| Sound attenuation De, dB | NL-H | 3 | 6 | 9 | 16 | 21 | 24 | 24 | 30 |
| Sound insulation value R, dB / Rw | NL | 3 | 4 | 7 | 8 | 13 | 15 | 13 | Rw 12 |
| Sound insulation value R, dB / Rw | NL-H | – | 7 | 9 | 16 | 25 | 27 | – | Rw 21 |
Materials and Construction Features
Installation and Application Notes
Application Areas
Application Note
When selecting an acoustic louver, airflow rate, face velocity, pressure drop, façade opening, rain risk, sound absorption requirement, material selection, surface coating and installation method should be evaluated together. For fresh air intakes, it is recommended that the face velocity does not exceed 2 – 2.5 m/s.
Get Technical Support for Acoustic Louver Selection
Acoustic louver selection should be based on airflow rate, louver dimensions, face velocity, noise reduction target, pressure drop, façade conditions and installation type.
You can request a project-specific technical assessment for your fresh air, exhaust air and façade acoustic louver applications.
