Valuation of Green Walls and Green Roofs as Soundscape Measures: Including Monetised Amenity Values Together with Noise-attenuation Values in a Cost-benefit Analysis of a Green Wall Affecting Courtyards

Knut Veisten,Maarten Hornikx,Jian Kang,Marjan Mosslemi,Ronny Klæboe,Yuliya Smyrnova

doi:10.3390/ijerph9113770

Abstract

Economic unit values of soundscape/acoustic effects have been based on changes in the number of annoyed persons or on decibel changes. The normal procedure has been the application of these unit values to noise-attenuation measures affecting the noisier façade of a dwelling. Novel modular vegetation-based soundscape measures, so-called green walls, might be relevant for both noisy and quieter areas. Moreover, their benefits will comprise noise attenuation as well as non-acoustic amenity effects. One challenge is to integrate the results of some decades of non-acoustic research on the amenity value of urban greenery into design of the urban sound environment, and incorporate these non-acoustic properties in the overall economic assessment of noise control and overall sound environment improvement measures. Monetised unit values for green walls have been included in two alternative cases, or demonstration projects, of covering the entrances to blocks of flats with a green wall. Since these measures improve the noise environment on the quiet side of the dwellings and courtyards, not the most exposed façade, adjustment factors to the nominal quiet side decibel reductions to arrive at an estimate of the equivalent overall acoustic improvement have been applied. A cost-benefit analysis of the green wall case indicates that this measure is economically promising, when valuing the noise attenuation in the quieter area and adding the amenity/aesthetic value of the green wall.

Highlights

Recent efforts of researchers, planners, architects, entrepreneurs and authorities dealing with increasing noise problems in European cities and urban areas have put an increased emphasis on the quality of soundscape [1,2,3]
Economic unit values of soundscape/acoustic effects have been based on changes in the number of annoyed persons or on decibel changes [9]
Acknowledging the theoretical objections to unit pricing of greenery, this paper aims to propose a practitioner approach proposing some initial unit values that can be tested in simplified cost-benefit analyses

Summary

Introduction

Planners, architects, entrepreneurs and authorities dealing with increasing noise problems in European cities and urban areas have put an increased emphasis on the quality of soundscape [1,2,3]. Noise is understood as a sound that is loud, unpleasant, unexpected, or undesired, while soundscape can be defined as a sound or combination of sounds that forms or arises from an immersive environment; referring to both the natural acoustic environment and sounds generated from human activity [2]. These aspects have received special attention through the protection of quiet areas in The Environmental Noise Directive (2002/49/EC). Neither is the acoustic aesthetics only a matter of noise protection, but it encompasses a soundscape entirety” [8]

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