Experimental evaluation of a vertical green system for indoor noise reduction

Abstract

Noise is a major challenge in open-plan offices, where irrelevant speech, casual conversations, phone ringing, and discussions frequently disrupt productivity, increase stress, and reduce overall workplace comfort. Common solutions to mitigate these issues include sound-absorbing surfaces and noise-reducing partitions. Meanwhile, green solutions—such as green roofs and vertical green systems—have been developed to integrate vegetation into the built environment, offering benefits like stress reduction, improved air quality, and enhanced mental well-being. These systems can also boost employees’ cognitive performance, further increasing productivity. However, indoor green walls can also reduce noise pollution and sound transmission in enclosed environments. Therefore, this study aims to address noise transmission in open-plan office environments by evaluating the effectiveness of a vertical green system as a noise-reducing partition. The study was conducted by testing a modular green wall system measuring 1.28 × 1.28 m under four different vegetation coverage conditions (bare, 1/3, 2/3, and full coverage). The results demonstrated that with full vegetation coverage, there was a noticeable reduction in sound pressure levels across most frequencies compared to the bare condition. The highest insertion loss (IL) was observed at 1250 Hz, measuring 16.2 dB. Additionally, increasing vegetation coverage was associated with a decrease in sound pressure levels across most frequencies.