Acoustic Panels—How to Choose a System for an Office, Hotel, or Conference Room?

Acoustic panels are wall and ceiling cladding elements that absorb sound wave energy in the 250–4,000 Hz range—the frequency band most critical for speech intelligibility. The selection of a system for a commercial facility is based on three parameters: the weighted sound absorption coefficient αw (in accordance with PN-EN ISO 11654), the sound absorption class from A to E, and the installed area determined by the room’s reverberation time analysis (PN-B-02151-4:2015). For offices, hotels, and conference rooms, the decisive factor is matching these parameters to the interior’s function, rather than the panel’s appearance alone.

What Are Acoustic Panels and How Do They Absorb Sound?

Acoustic panels absorb sound energy by converting sound waves into heat within their porous structure or through mechanical resonance. The two most commonly used mechanisms are porous absorption (mineral wool, melamine foam, PET polyester nonwoven fabric) and resonant absorption (perforated MDF or HDF panels with a layer of mineral wool behind the holes).

Commercial buildings primarily use composite systems consisting of a CPL surface panel or veneer, calibrated perforations (8% to 22% open area), and a mineral wool core with a density of 40–80 kg/m³. This design absorbs a wide frequency range—from 125 Hz with an appropriate air gap up to 4,000 Hz.

The PN-EN ISO 11654 standard defines five sound absorption classes (A–E) and the weighted coefficient αw, which serves as a single numerical measure of a panel’s effectiveness. This is a key parameter in architectural specifications—the higher the αw value, the less acoustic cladding is needed to achieve the specified reverberation time.

In commercial building projects, acoustic panels are often used in conjunction with a second acoustic system: movable walls with enhanced sound insulation. The first solution reduces reverberation inside the room (αw parameter), while the second provides sound insulation between adjacent rooms (Rw parameter). Together, these two solutions provide comprehensive acoustic treatment for conference rooms, hotel lobbies, and banquet halls. A detailed description of the movable systems is available on the Optimal Poland movable walls category page.

Key Acoustic Parameters – αw, Absorption Class, and NRC

The specifications for acoustic panels in a commercial facility should always include three values: αw, absorption class A–E, and NRC. Each of these describes a different aspect of acoustic performance, and they are not all interchangeable.

In architectural practice, Class A refers to a premium panel with nearly total sound absorption (αw ≥ 0.90)—this is the standard for office ceilings and conference room walls. Class B (αw 0.80–0.85) works well as wall cladding in hotel restaurants and lobbies. Class C (αw 0.60–0.75) is used to complement the side walls in conference rooms—to maintain sound clarity without creating a “deaf” room effect. Classes D and E serve primarily decorative purposes.

The use of NRC alone in the European specification is incomplete. This parameter covers only four octave bands (250–2000 Hz) and is a simple arithmetic mean. The αw index, in accordance with PN-EN ISO 11654, additionally takes into account the 4000 Hz band (important for speech articulation) and introduces the shape indices L, M, H, which describe the frequency range in which the material performs most effectively. For a complete characterization at low frequencies (below 250 Hz, where air conditioning noise and foot traffic occur), an analysis of the full αp curve in third-octave bands is necessary. For commercial buildings in Poland, the binding specification criterion remains αw in accordance with PN-EN ISO 11654.

How to Calculate the Surface Area of Acoustic Panels for a Room

The surface area of acoustic panels for a given room is calculated based on the required reverberation time T specified in the PN-B-02151-4:2015 standard (Building acoustics—Noise control in buildings—Part 4: Requirements for reverberation conditions and sound absorption in rooms, and guidelines for testing). The basic formula is Sabine’s equation:

T = 0.16 × V / A

where T is the reverberation time in seconds, V is the volume of the room in m³, and A is the total sound absorption in Sabine m². The absorption coefficient A is the sum of all surfaces: A = Σ (Si × αi), where Si is the area of the i-th surface, and αi is its absorption coefficient at a given frequency.

The PN-B-02151-4:2015 standard specifies acceptable reverberation times for various room uses. Typical design values for commercial buildings:

The values in the table represent the maximum permissible reverberation times for rooms in use, applicable when the rooms are fully equipped with functional furnishings. The architect should conduct an acoustic analysis (most commonly using Odeon, EASE, or CATT-Acoustic software) or commission one from an acoustic specialist, especially for spaces larger than 500 m³. For rooms with atypical proportions—such as atria, multi-story halls, and long corridors—Sabine’s equation requires adjustment, as its assumption of a diffuse field is no longer valid.

In design practice, for open-plan offices, approximately 30–50% of the ceiling area is covered with Class A panels, and for conference rooms, the rear wall (behind the audience, opposite the presenter) is also covered —this is the surface from which sound waves reflect, generating a return echo. This treatment reduces the reverberation time from the typical 1.2–1.8 seconds in an untreated interior to the required 0.6–0.8 seconds. The Optimal Poland online configurator provides support for quantitative specifications.

Acoustic panels for open-plan offices

In open-plan offices, acoustic panels serve two purposes: they shorten the reverberation time (reducing echoes) and lower the background noise level in the speech frequency range, which improves the intelligibility of phone calls and conversations taking place nearby. The PN-B-02151-4:2015 requires T ≤ 0.8 s for offices larger than 200 m³—without acoustic treatment, this value is practically unattainable in modern interiors with large amounts of concrete, glass, and flat surfaces.

The most cost-effective solution is Class A ceiling panels using cassette technology (module dimensions: 600 x 600 or 1,200 x 600 mm), installed in a T-24 or T-15 suspended ceiling system. These are complemented by wall panels that serve a dual purpose: they absorb sound in the 500–4,000 Hz range and act as decorative cladding.

In design practice, three configurations have proven effective:

• Open-plan space for up to 50 people: Class A ceiling panels (covering 40–60% of the surface area), walls behind desks lined with vertical panel modules (for decorative and acoustic purposes).
• Open-plan space for up to 150 people: Class A ceiling covering 80–100% of the area, movable acoustic partition walls between functional zones, and meeting rooms (focus rooms) with fully equipped interiors.
• Hybrid zones (open space + meeting rooms): acoustic panels on shared walls, movable acoustic partitions to divide the space—a flexible solution for offices with changing layouts.

When designing an office, it’s worth considering a system of movable acoustic walls—it allows you to transform a single space into a workshop or conference room without altering the building’s structure. We describe the details of this solution on the Optimal movable acoustic wall system page.

An example of flexible office space layout is the project at the Sii office — a small movable wall with hidden side profiles and a concrete-look laminate serves as the backdrop for the recreation area and allows for a quick expansion of usable space when the interior layout needs to be changed.

Acoustic panels for hotels—lobbies, restaurants, conference rooms

Hotels require acoustic treatment in several areas with different functional requirements: the lobby (first impression, background noise), the restaurant (conversation comfort at tables, reduction of the Lombard effect), bar or wellness area (reverberation control in high-ceilinged rooms), conference rooms (speech intelligibility). Each zone has a different reverberation time specified in PN-B-02151-4:2015 and a different aesthetic permitted by the interior design.

The Lombard effect is a phenomenon in which restaurant guests unconsciously raise their voices in an attempt to speak over the reverberation and noise of other conversations. The result: the noise level in the dining room skyrockets, and the comfort of conversation decreases. Acoustic treatment reduces this phenomenon, improving the guests’ comfort and reducing staff fatigue.

Hotels most commonly use two strategies:

• Lobbies and restaurants: Class A or B acoustic ceiling panels integrated with lighting, and veneered wall panels as a visual focal point—the decorative cladding also serves as sound-absorbing material.
• Hotel conference rooms: Class A on the side and rear walls, Class A or B ceiling (depending on the height), and movable acoustic partitions that divide the banquet hall into smaller sections.

The Optimal 110 ALU system was used in the conference area of the StayInn Hotel. The project specifications required maintaining a high level of acoustic performance to allow for the simultaneous hosting of different events in adjacent rooms. The natural stone-colored finish in shades of gray remained consistent with the hotel’s existing interior design.

The project at the Gromada Hotel, a venue with a long-standing tradition, utilizes movable walls with high acoustic performance and a wood-grain laminate finish. The design maintains a seamless surface—with no vertical joints and concealed side edges—thereby providing a neutral backdrop for the historic mosaic located nearby.

At the Focus Hotel Premium Lublin, the Optimal 110 system was used in three different applications: as a movable partition wall separating the hallway, with a total length of over 15 meters, a partition wall separating the ballroom, and a wall in the restaurant covered with custom-designed wallpaper. This project demonstrates that the same structural system allows for a wide variety of surface finishes—ranging from neutral laminate to custom-designed wallpaper.

Acoustic panels for conference rooms and auditoriums

A conference room requires speech intelligibility, measured by the STI (Speech Transmission Index), of at least 0.60, and in reception rooms, above 0.70. This value depends on the reverberation time, the signal-to-background-noise ratio, and the room’s frequency response—which is why acoustic treatment is a fundamental requirement here, rather than merely a finishing touch.

For a conference room with a volume of 100–300 m³, the target reverberation time T is 0.6–0.8 s in the 500–1000 Hz frequency band. In design practice, this means:

• Full ceiling coverage with Class A panels (or Class B panels for larger volumes and larger window areas).
• The rear wall (behind the audience, opposite the presenter), which is 100% covered with Class A panels—this is the surface responsible for the reverberation.
• The side walls are partially (40–60%) covered with Class B or C panels—to maintain clarity without creating a “deaf” room effect.
• Exclusion of glass surfaces from the image projection area.

In university auditoriums (volume 500–2,500 m³), large-format acoustic panels are installed on the side and rear walls and integrated with the sound system. For rooms larger than 1,000 m³, an additional acoustic analysis with 3D modeling (Odeon, EASE) is required.

The Optimal 110 Plus ALU system was installed at the Lublin Conference Center in semi-automatic mode. A distinctive feature is the cross-connection of the walls, which allows for flexible division of the conference room into four independent modules. The natural veneer finish gives the space a prestigious look consistent with the facility’s standard.

The project at the Lodz University of Technology features the tallest mobile stepped wall ever manufactured by Optimal Poland—the OPTIMAL 110 Sky system. The tallest module is 10.85 m high and, despite its considerable weight, can be operated by a single person thanks to the power-assisted mechanism. Its safety and technical specifications are confirmed by the National Technical Assessment issued by the Building Research Institute. The installation is located in the Prof. T. Paryjczak Auditorium at the Faculty of Chemistry (Alchemium) of the Lodz University of Technology.

At the UMCS Faculty of Political Science, a stepped wall—nearly 6 meters high at its highest point—was installed and is operated semi-automatically. The finish, featuring wood-grain laminate panels in a beech wood color, was chosen to complement the aesthetics of the university’s interior.

Materials, Finishes, and Design of Acoustic Panels

The finish material of an acoustic panel determines three key factors: durability in a commercial facility, fire rating, and aesthetics that complement the interior design. Four main types of finishes are commonly used in commercial facilities: CPL laminates, natural veneer, technical fabrics, and lacquered MDF. This choice of finishes is reflected in Optimal Poland’s projects—ranging from natural veneer at the Lublin Conference Center, through wood-effect laminates (Gromada Hotel, UMCS), to concrete-effect laminate (Sii).

CPL and HPL—two decorative laminate technologies

CPL (Continuous Pressure Laminate) and HPL (High Pressure Laminate) are two technologies for decorative laminates manufactured from the same raw materials: decorative paper and overlay impregnated with melamine resins, and kraft paper impregnated with phenolic resins. The difference lies in the manufacturing process.

CPL is produced in twin-belt presses using a continuous process, typically at a pressure of 30–70 bar in an 8–15-second cycle. HPL is manufactured in multi-deck presses at higher pressure (≥50 bar, 20–60-minute cycle). As a result of this difference in the manufacturing process, HPL offers slightly higher resistance to mechanical damage and abrasion—a difference that is significant in high-traffic areas but less noticeable in typical applications such as movable walls in conference rooms, offices, or hotel rooms.

For most interior applications of movable walls—low exposure to mechanical impact, no contact with water, and stable climatic conditions— CPL of a grade appropriate for the application meets the technical requirements and is functionally equivalent to HPL. A bid specification requiring “HPL” for typical commercial interior applications can be met with CPL laminate without any loss of functionality, while offering a wider range of available sizes and shorter lead times.

When HPL Has a Real Advantage

HPL remains the recommended choice for applications with specific mechanical or climatic requirements:

• Hotel lobbies and high-traffic reception areas that are subject to impacts from luggage, service carts, or furniture.
• Surfaces in wet areas—hotel bathroom entryways, wellness areas, and swimming pools.
• Countertops, reception desks, mechanically loaded surfaces, and horizontal surfaces.
• Applications requiring increased chemical resistance—laboratories, treatment rooms, food service areas (exposure to industrial detergents).

For typical wall paneling in conference rooms, offices, and hotel rooms, CPL of a grade suitable for the application meets the same performance requirements as HPL.

What does this mean for an architect?

Optimal Poland supplies acoustic panels and cladding with a CPL finish from leading European manufacturers of decorative laminates. For projects, this means access to a wide range of designs (wood, concrete, stone, solid colors, original patterns), compliance with fire reaction standards (minimum class B-s1,d0 according to PN-EN 13501-1+A1:2010), and full functionality for typical mobile wall applications—with a wider range of available sizes and shorter lead times than with HPL.

Natural veneer

Natural veneer is a thin sheet of hardwood (oak, ash, walnut, wenge) with a thickness of 0.5–0.9 mm, bonded to an MDF or HDF substrate. A premium finish for prestigious venues—used, among other places, at the Lublin Conference Center. It requires a matte or semi-matte varnish with a minimum fire reaction class of B-s1,d0 according to PN-EN 13501-1+A1:2010.

Technical Fabrics

Acoustic fabrics (technical polyester, microfiber, flame-retardant fabrics) are used as the outer layer of resonance-absorbing panels. Available in hundreds of colors and patterns, they are easy to match to the visual identity of a hotel or office. However, they require hygiene monitoring in high-traffic areas—CPL is a better choice for restaurants and bars.

Custom Finishes

In hotel projects, custom finishes are also common—such as wallpaper with an original design (Focus Hotel Premium Lublin, restaurant area) or laminate that mimics unusual materials: architectural concrete, natural stone (Hotel StayInn). The modular wall construction remains the same in both cases—only the outer layer changes.

Optimal Poland’s Project Portfolio – Acoustics of Spaces

Optimal Poland designs, manufactures, and installs movable wall systems for commercial facilities in Poland and in export markets. Most of its portfolio consists of systems with acoustic properties—a solution similar to acoustic panels—which, when used together, provide comprehensive acoustic treatment for conference rooms, hotel lobbies, and multifunctional spaces.

Each project includes an acoustic analysis, selection of system parameters, delivery of BIM models to the architect (available on BIMobject), manufacturing, installation, and after-sales service. For facilities with specific mechanical requirements—such as the Lodz University of Technology—the technical parameters are confirmed by a National Technical Assessment issued by the Building Research Institute. A complete list of projects can be found on the Optimal Poland Projects page.

FAQ – Frequently Asked Questions About Acoustic Panels

Summary

Selecting acoustic panels for a commercial facility involves three steps: determining the reverberation time in accordance with PN-B-02151-4:2015 for the given room function, selecting the absorption class (A–E) in accordance with PN-EN ISO 11654, and calculating the cladding area using Sabine’s equation. The choice of finish—CPL, veneer, fabric, or custom laminate—does not affect the acoustics when the panel construction remains the same, but it determines the durability and aesthetics of the facility. For typical applications of movable walls, CPL of a class suitable for the application is functionally equivalent to HPL, which expands the selection of available decors and formats.

If you are designing an office, hotel, or conference room and need assistance specifying an acoustic panel system, use the Optimal Poland online configurator or view the full product lineup on the Acoustic Panels page. BIM models of Optimal systems are available on the BIMobject platform.