Biophilic Acoustic Solutions for High-Ceiling Buildings: What Owners and FMs Should Know

While high ceilings are grand and visually appealing, they contribute to sound reverberation, creating a loud, echoing soundscape of muddied noises. Biophilic design offers unique acoustic solutions for high ceiling rooms—living walls and porous natural materials.

Incorporating Greenery Into Acoustic Design

Biophilic design is an approach to urban planning that mimics the natural environment to reinforce a relationship with nature while enhancing occupant comfort. Engineers incorporate trees, grasses, shrubs, mosses, vines or ornamental plants into walls, ceilings, and roofs. They also draw inspiration from nature, leveraging natural materials, light, and ventilation. 

The larger and more complex the layouts get, the more creative the approach. For an office space with high ceilings, vertical gardens, and a living facade are easy enough to achieve with climbing and trailing plants. A large mall, on the other hand, may require a park-like atrium with tall foliage or a green canopy suspended over open-air walkways. 

This design trend was formally introduced to the field of architecture in 2006 at the landmark Rhode Island conference. In the decades since, it has become mainstream and is widely accepted and used. Its popularity is driven by more than just aesthetics, but also a need to address the adverse effects of urbanization. 

Urban areas are becoming larger and more populated. Experts estimate that 70% of people will live in cities by 2050. Already, approximately 4.4 billion live in metropolitan areas. As this number rises, cities will become increasingly dense, polluted and loud. 

Biophilic architecture has emerged as a promising solution to this looming problem because it addresses a host of issues related to urbanization. In addition to improving acoustic conditions, it mitigates the heat island effect and enhances air quality.

Acoustic Properties of Biophilic Architecture

Whether professionals are planning new construction or retrofitting an existing building, integrating vertical gardens, moss walls, porous natural wood, and plant canopies improves acoustics, air quality, and aesthetic appeal. 

Vegetation acts as an acoustic solution for high ceiling rooms because it naturally diffuses, scatters, and absorbs noise. Due to their porous structure, leaves can absorb sound waves. Stems and branches scatter sound, preventing direct reflections. Of course, factors such as vegetation coverage, plant species, substrate thickness, and moisture level influence the effectiveness. For instance, the absorption coefficient is five to 10 times higher in dry soil.

Professionals can use virtually any plant for a living facade or canopy. Even common houseplants have sound-absorbing properties. For instance, tradescantia zebrina—a perennial colloquially known as the inch plant—has a noise reduction coefficient (NRC) between 0.23 and 0.52 depending on its thickness. It can absorb up to 52% of the sound energy that strikes it.

Biophilic design also contributes to indoor air quality, as many plants can naturally purify the air by removing pollutants. All plants absorb carbon dioxide—which is considered a pollutant when released in excess—and produce fresh oxygen through photosynthesis. Some species can also address particle pollution from vehicle exhaust. 

Aesthetics may seem inconsequential in comparison, but building professionals understand the importance of visual appeal. Whether vegetation climbs, creeps, or flowers, it is appealing. While shape, scent, and color influence people’s attractiveness perception, plants generally add character to a space, create a sense of naturalness, and enhance overall ambience.

The Viability of Biophilic Acoustic Solutions

With proper planning, builders can incorporate greenery into almost any building’s walls, roof, ceiling, or facade. However, they cannot place it between floors or on every internal wall. This means vegetation cannot replace conventional sound-dampening materials. 

Take multitenant properties, for example. Property managers can install green walls in the hallways of an apartment complex because they offer easy access for maintenance. However, they cannot place plants in units—where sound dampening is arguably most important—to reduce the noise between rooms because upkeep would be impractical. 

Biophilic architecture is not limited to living walls, however. Professionals can use porous natural wood or volcanic rock. They can even leverage conventional, proven solutions, such as fiberglass batts. When paired with vertical gardens and living canopies, insulation can amplify sound absorption and increase the building’s energy efficiency.

Selecting the Best Noise-Dampening Materials

When selecting acoustic solutions for high ceiling rooms, decision-makers must evaluate each option’s NRC and sound transmission class (STC) ratings. Moss, wood, fiberglass, stone, and vinyl block or absorb sound at varying levels. 

Mass-loaded vinyl (MLV) is the industry’s preferred choice for blocking sound transmission between rooms, as it is cost-effective and versatile. High-quality MLV barriers have STC ratings between 21 and 34, meaning loud speech from the opposite side of a wall remains audible but is almost unintelligible.

Biophilic alternatives with excellent acoustic properties have entered the market. For instance, mineral wool is a type of insulation made by melting basalt rock and recycled industrial slag. The molten material is spun into fine fibers and cut into dense batts.

A 2-inch-thick mineral wool panel has an STC rating between 45 and 52 and an NRC ranging from 0.95 to 1.09, giving it excellent sound deadening properties. Compared to fiberglass batts, it has a 22% to 37% higher R-value per inch. However, it is roughly 50% more expensive than fiberglass and is unpleasant to work with (tiny slivers can pierce skin and enter the lungs).

Combining safe, cost-effective, conventional insulation materials with living canopies, walls, and roofs is an excellent way to optimize sound reduction, energy efficiency, and occupant comfort. However, it matters what these materials are attached to. Whether ivy clings to concrete or a multilayered facade comprising waterproofing, irrigation, and substrate impacts its STC rating.

A Multifaceted Approach to Biophilic Design

Biophilic design does not promise a one-size-fits-all solution. A substrate covered in moss may work for a library with high ceilings but still be ill-suited for sound-dampening in an office. Factors such as plant species, insulation material, substrate thickness, and vegetation composition can affect sound absorption and diffusion. 

Incorporating biophilic elements into modern architecture remains critical, however. The built environment is responsible for an estimated 40% of the world’s energy-related carbon dioxide emissions. Natural light, ventilation, and vegetation passively improve heating, air circulation, and carbon sequestration, thereby minimizing buildings’ energy losses. 

Building industry professionals must take a multifaceted approach to biophilic architecture. It can help them achieve desirable acoustic conditions, pleasant views, high indoor air quality, and exceptional occupant comfort. Moreover, it creates a self-sustaining feedback loop. Plants thrive under real-world conditions with proper daylighting and natural ventilation.

Glass walls, skylights, solar tubes, and clerestory windows allow light in, while reflective surfaces ensure sunlight reaches shadowed interior spaces. Smart buildings can use daylighting systems to maximize natural light while minimizing power consumption. 

Natural ventilation uses strategically placed openings in the building envelope to allow airflow into and out of the building. Operable windows, vents and narrow rooms passively support airflow, reducing the strain on smart building systems. Air movement is driven by changes in wind speed and barometric pressure.

Pick Acoustic Solutions for High Ceiling Rooms

Natural wood, volcanic rock and vegetation are excellent biophilic acoustic solutions for high ceiling rooms. Conventional insulation materials can enhance their sound-dampening performance while also contributing to energy efficiency and occupant comfort. Decision-makers should carefully consider their options to ensure they pick synergistic combinations.