From improving the visual appeal of a building to creating a more calming and soothing indoor environment to improving the quality of life in the building environment, green walls can do it all. Their role in improving air quality and reducing energy costs for heating and cooling buildings has been well documented. However, green walls and noise attenuation is something that needs to be talked about more. Despite the fact that green walls offer numerous benefits to a building in terms of efficiency, beauty, and sustainability, more studies need to be conducted on exploring their acoustic insulation. The limited studies that have been done conclude that green walls have significant potential as sound insulation tools for buildings.
Plants and trees have been used along roads and highways to reduce noise and green walls take this a step further. Vegetation is known to block high-frequency sound naturally while the supporting structure aids in lowering low-frequency noise. They help in reducing noise levels by reflecting, refracting, and absorbing acoustic energy thereby providing a pleasant, healthier indoor environment. A study called ‘Evaluation of Green Walls as a Passive Acoustic Insulation System for Buildings’, showed that the walls exhibited a weighted sound reduction index of 15db as opposed to conventional walls. It further showed that the green walls provided a weighted sound absorption coefficient of 0.40.
Zaloa Azkorra, an agricultural engineer of the UPV/EHU-University of the Basque Country while conducting research on the benefits of green walls at the University School of Mining and Public Works Engineering found that green walls can be used in buildings to achieve acoustic improvements. Conducted in a reverberation chamber, the noise absorption test featured a range of frequencies, and living walls were found to perform very well in high as well as low frequencies with respect to noise reduction. This is a remarkable finding since other materials that are used in the construction of buildings only perform well at either high or low frequencies.
And it’s not just about real plants. Artificial plants and trees contribute towards reducing sound levels by reflecting and scattering sound with the help of their trunks, branches, twigs, and leaves. In some cases, the foliage or vegetation can also help in sound absorption, and hence, green walls making use of such specialized or preserved plants life can aid sound attenuation.
Simply put, green walls with real or artificial plants have varied capabilities as sound insulation tools for buildings.