Hoe specificeer je biofiele akoestische wandsystemen in 5 stappen
A repeatable decision framework for architects, acousticians, and consultants, from the acoustic brief to the installed system. Covers performance data, fire compliance, and certification mapping.
Table of contents
Why specifying biophilic acoustic systems is different
Specifying biophilic acoustic solutions should be straightforward. In practice, it rarely is.
Project teams face a consistent set of obstacles: acoustic data tested under conditions that don't match the project, fire classifications that are unclear or incomplete.
The result is a specification process driven by assumption rather than evidence. Materials are selected for how they look, not how they perform.
This article proposes a different approach. A structured 5-step decision framework from the acoustic brief to the complete system specification — with fire compliance, certification mapping and documentation at every stage.
#Le cadre de spécification en 5 étapes
From the acoustic brief to the installed system
Each step builds on the previous one. Skipping a step — or reversing the order — is where most specification issues originate. Selecting a product before defining the acoustic target is the most common mistake.
The framework applies to any biophilic acoustic material. This article illustrates each step with Greenmood preserved systems — Ball Moss, Velvet Leaf, Forest, Reindeer Moss, and Cork Acoustic Tiles — where acoustic, fire and sustainability data is available for each step.
How to define acoustic targets for interior spaces
Every acoustic specification begins with a question: what should this space sound like?
The answer depends on how the space will be used, how many people will occupy it, what surfaces already exist and what level of speech intelligibility or comfort is required.
The two most important metrics for interior acoustic comfort:
- Réverbération Time (RT60) — How long sound persists in a space after the source stops. For open offices, the target is generally 0.5–0.8 seconds.
- Background Noise Level — Measured in dB(A). Most offices exceed 45 dB(A), above the threshold for sustained concentration. Reducing reverberation directly impacts perceived noise.
Before selecting a material, the project team must establish:
A common rule of thumb: in a typical 200 m² open-plan office, reducing the RT60 from 1.2 seconds to 0.6 seconds may require approximately 60–80 m² of absorptive surface with an NRC above 0.65, depending on existing finishes and room geometry. This figure should be validated by an acoustician during design development, but it provides a useful starting point for feasibility discussions.
This step is not about choosing a product. It is about defining what the product must achieve.
Choosing between moss, cork and preserved foliage for acoustic performance
Once the acoustic target is defined, the next decision is to determine which material family best meets both the performance requirement and the design intent.
In biophilic acoustic design, three material families are most commonly specified: preserved moss, preserved foliage and natural cork. Each absorbs sound at different rates, with different frequency profiles, and each suits different project contexts.
| Material | NRC | ISO Class | Best application |
|---|---|---|---|
| Ball Moss | 0.73 | D (ISO 11654) | Large surfaces, ceilings, open-plan offices, atriums — highest absorption in the collection |
| Velvet Leaf | 0.65 | C (ISO 11654) | Accent walls, lounges, corridors, hospitality — intermediate absorption with visual depth |
| Cork Acoustic Tiles (Parenthèse, Sillon, Brickx, Morse) |
Tested ISO 11654 | Tested | Meeting rooms, branded spaces, modular walls - designed by Alain Gilles in four architectural patterns |
| Reindeer Moss | System-level | Part of system | Background textures, mixed compositions — used in compositions Forest and custom combinations |
The selection depends on three factors:
From left to right: Ball Moss (NRC 0.73) · Velvet Leaf (NRC 0.65) · Cork Acoustic Tiles — three material families, each suited to different acoustic and design requirements.
- Performance priority. If the primary objective is maximum sound absorption per square metre, Ball Moss with an NRC of 0.73 offers the highest absorption. For moderate absorption with a distinctive visual impact, Velvet Leaf with an NRC of 0.65 offers strong mid-frequency performance with visual complexity. For modular applications, Cork Acoustic Tiles combine pattern flexibility and tested acoustic data.
- Design language. Cork panels offer four architectural patterns — Parenthèse, Sillon, Brickx et Morse — designed by Alain Gilles, where acoustic performance is integrated into a deliberate design vocabulary. Preserved moss and Forest compositions offer organic, textural qualities that cannot be replicated with synthetic alternatives.
Cork Acoustic Tiles — four architectural patterns by Alain Gilles: Parenthèse, Sillon, Brickx and Morse. Modular wall systems where acoustic performance meets design intent.
- Application context. Ceilings and large open walls favor Ball Moss for uniform absorption. Brand spaces and meeting rooms favour Cork for pattern control. Mixed compositions using multiple foliage types — such as in the Forest collection — create visual depth while maintaining acoustic integrity at system level.
At this stage, the specification should include the material family, target surface area and expected NRC contribution — validated against the acoustic target established in Step 1.
Fire classification requirements for preserved green wall systems
Fire compliance must be confirmed before a product enters the specification — not after procurement. This is the step most often deferred, and the one most likely to cause project delays or forced substitutions.
The critical distinction, covered in depth in our fire safety guide, falls between material-level testing and system-level testing. A fire test on a flat moss sample does not represent the performance of a complete wall assembly with backing, adhesive, frame and fixing.
Four questions to verify fire documentation:
Greenmood fire classifications (system-level):
| Standard | Classification | Region | Basis |
|---|---|---|---|
| EN 13501-1 | B-S2-d0 | EU / UK | Complete assembly tested |
| ASTM E84 | FSI 0 / SDI 15 | US / North America | Complete assembly tested |
These classifications apply to the installed system — not to individual material samples. If any of these conditions is unclear for a product under consideration, the specification is not ready to proceed.
How biophilic acoustic products contribute to LEED v5, BREEAM and WELL credits
Many projects today target environmental or wellbeing certification — LEED, BREEAM, WELL or regional equivalents. Biophilic acoustic solutions can contribute to multiple credit categories when properly documented, but this contribution must be identified at the specification stage, not retroactively.
| Credit category | How biophilic acoustics contributes | Required documentation |
|---|---|---|
| Indoor Environmental Quality (LEED EQ / BREEAM Hea / WELL Son) |
Certified sound absorption data (Ball Moss NRC 0.73, Velvet Leaf NRC 0.65). Contribution to RT60 reduction. Improvement in speech intelligibility and occupant comfort. | NRC test reports (ISO 11654). In-situ measurement data when available. |
| Materials & Resources (LEED MR / BREEAM Mat) |
Natural preserved materials with traceable sourcing. Extended life cycle with zero replacement. No synthetic components in the main foliage. Cork bark harvested without cutting the trees (renewable every 9 years). | Material sourcing documentation. Lifecycle data. Preservation process description. |
| Biophilic Quality (LEED v5 Connexion avec la nature / WELL Mind) |
Direct, non-representational connection to nature using real plant material. Sensory richness and visual complexity. Alignment with the 12 biophilic attributes recognised by LEED v5. | Product composition documentation. Biophilic attribute mapping. Installation photography. |
The operational advantage of preserved systems in certification contexts is significant. Unlike living installations, preserved walls require no irrigation logs, no plant replacement records, no seasonal maintenance schedules and no ongoing horticultural management documentation. This simplifies the most time-consuming element of certification: operational compliance over the building lifecycle.
What the complete specification of a biophilic wall system includes
The last step is where most specification documents fall short. They name a product — "preserved moss wall" — without defining the system: the backing, the mounting, the interface with the substrate, the edge conditions, the maintenance protocol (or lack thereof).
A complete specification for a biophilic acoustic system includes:
When a green wall is specified as a system — with acoustic data, fire classification, dimensional precision and certification mapping — it ceases to be a decorative choice and becomes a documented, defensible architectural element.
System-level specification in practice: custom-fabricated panels, precise dimensional fit and wrapped corners that follow the architecture — not generic flat panels cut on site.
#En pratique : le projet Wisecom, Paris
Measured acoustic improvement in a real workspace
Wisecom - Paris, France
For the Wisecom project in Paris, acoustic comfort was the primary design driver. Noise levels in the open workspace affected concentration, speech intelligibility and day-to-day usability. The brief required reducing reverberation without partitioning the space — no dividers, no layout changes.
The solution, designed and delivered by Greenmood France, combined two complementary interventions:
- Preserved Ball Moss walls — contributing to broadband sound absorption while introducing a strong natural, biophilic dimension to the interior.
- Suspended acoustic circles above workstations — improving reverberation control precisely where it matters most, while visually structuring the open space without physical barriers.
Wisecom, Paris — Ball Moss walls combined with suspended acoustic circles. Measured result: −10 dB across the entire open workspace.
The measured result — a 10 dB reduction across the entire workspace — represents a substantial improvement in acoustic comfort, with a direct impact on concentration, communication clarity and perceived noise levels.
This project illustrates the framework in action: an acoustic target was defined (reduce reverberation in the open workspace), materials were selected for their performance and design suitability (Ball Moss walls + suspended elements), fire compliance was verified for the French market, and the solution was specified and installed as a complete system.
#Acoustic performance data: Greenmood product reference
| Product | NRC | ISO Class | Fire (EU) | Fire (US) | Care |
|---|---|---|---|---|---|
| Ball Moss | 0.73 | D | B-S2-d0 | FSI 0 / SDI 15 | None |
| Velvet Leaf | 0.65 | C | B-S2-d0 | FSI 0 / SDI 15 | None |
| Sparse Forest (mixed composition) |
System-level | System-level | B-S2-d0 | FSI 0 / SDI 15 | None |
| Reindeer Moss | System-level | System-level | B-S2-d0 | FSI 0 / SDI 15 | None |
| Cork Acoustic Tiles (Parenthèse · Sillon · Brickx · Morse) |
Tested ISO 11654 | Tested | B-S2-d0 | FSI 0 / SDI 15 | None |
Preserved moss texture detail — the variation in density, depth and surface structure between foliage types directly influences acoustic absorption characteristics.
#Specification scenarios by space type
What to specify for open-plan offices, meeting rooms and lobbies
| Space type | Target RT60 | Recommended product | Indicative surface | Notes |
|---|---|---|---|---|
| Open-plan office (200 m²) |
0.5–0.8 s | Ball Moss walls + suspended acoustic elements | 60–80 m² absorptive surface (NRC ≥ 0.65) | Combine wall treatment with ceiling elements for the best broadband absorption. See Wisecom case study for a measured example (−10 dB). |
| Meeting room (30 m²) |
0.4–0.6 s | Cork Tiles collection (Sillon or Parenthèse) or Velvet Leaf feature wall | 8–14 m² absorptive surface | Cork panels offer pattern control suited to branded or formal environments. Velvet Leaf offers a more organic alternative. Speech intelligibility is the priority metric. |
| Lobby / reception (100–300 m²) |
0.8–1.2 s | Forest or large-scale installation of Ball Moss feature | Variable - depends on volume and ceiling height | High-volume spaces require acoustic modelling. Forest compositions offer large-scale visual impact while contributing to system-level absorption. Custom fabrication (wrapped corners, non-standard panels) is often required. |
These are indicative starting points. Greenmood provides project-specific acoustic estimates during the specification consultation process, taking into account room geometry, existing finishes and target performance levels.
Biophilic acoustic treatment integrated into a professional workspace — the specification scenarios above translate directly into installations like this.
#Documentation provided at each project phase
| Project stage | Available from Greenmood |
|---|---|
| Concept / briefing | Product sample box. Configurator . Preliminary acoustic estimates based on room type and surface area. |
| Schematic design | Technical data sheets per product. NRC and fire classification summaries. Material composition descriptions. |
| Design development | Full acoustic test reports (ISO 11654). Fire test reports (EN 13501-1 / ASTM E84). Pack support LEED with credit mapping. CAD plans and dimensional drawings. |
| Construction documents | Panel-by-panel dimensional specifications. Installation guides. Custom fabrication documentation (wrap corners, non-standard panels). |
| Post-installation | As-built documentation. Maintenance protocol (confirming zero ongoing maintenance). Photographs for certification submissions. |
#Specification checklist
Verify before the product enters the specification document
#Frequently asked questions
What NRC rating do I need for an open-plan office?
For open-plan offices targeting an RT60 of 0.5–0.8 seconds, specify materials with an NRC of 0.65 or above. Ball Moss (NRC 0.73) and Velvet Leaf (NRC 0.65) both meet this threshold. The required surface depends on room geometry and existing finishes — as a starting point, plan for 30–40% of the ceiling or wall area to be treated with absorptive material.
Do preserved moss walls require fire testing?
Yes. Preserved moss walls must be fire tested as complete assemblies — not as isolated material samples. A test on a flat moss sample does not represent the fire behaviour of the installed system. Greenmood systems are rated B-S2-d0 under EN 13501-1 (EU/UK) and FSI 0 / SDI 15 under ASTM E84 (US), based on system-level testing. Full test reports are available on our downloads page.
Can biophilic acoustic products contribute to LEED v5 credits?
Yes. Preserved biophilic systems can simultaneously contribute to multiple LEED v5 credit categories: Indoor Environmental Quality (acoustic performance), Materials and Resources (natural sourcing, extended life cycle), and the new biophilic quality credit Connection with Nature. A Pack support LEED is available with detailed credit mapping for consultants.
What is the difference between sound absorption and sound insulation?
Acoustic absorption reduces reverberation within a space — it is measured by NRC and improves speech intelligibility and acoustic comfort. Sound isolation blocks sound transmission between between spaces — it is measured by STC. Preserved mosses and Cork Walls provide acoustic absorption. They significantly improve acoustic conditions within a room but are not designed to prevent sound from travelling to adjacent spaces. For more details, see our acoustic performance guide.
How much preserved moss wall area do I need to improve acoustics?
As a guideline, a 200 m² open-plan office may require 60–80 m² of absorptive surface with an NRC above 0.65 to reduce the RT60 from 1.2 seconds to 0.6 seconds. The exact requirement depends on existing finishes, room geometry and ceiling height. In the Wisecom project, combining Ball Moss walls with suspended acoustic elements achieved a measured reduction of −10 dB. Greenmood provides project-specific acoustic estimates during the specification process.
Do preserved green walls require ongoing maintenance?
No. Preserved green wall systems require no irrigation, no plant replacement and no ongoing horticultural maintenance. This also simplifies certification documentation — no irrigation logs, no seasonal maintenance records, no replacement schedules. The system performs as installed, for its expected lifespan, at no operational cost.
#Complementary A&D guides
This article consolidates the specification thinking from three complementary articles, each covering one dimension of the framework in depth:
Key takeaway
Biophilic acoustic solutions perform best when they are specified as systems — with acoustic targets, fire compliance, certification mapping and documentation integrated into the process from the start. The framework is simple. The discipline to follow it is what distinguishes specification from selection.
