A sustainable development perspective on urban-scale roof greening priorities and benefits

TL;DR

This study assesses urban roof greening in Hong Kong using geospatial data, highlighting its potential to significantly increase greenspace exposure and economic benefits, while playing a limited role in heat mitigation and carbon offsetting.

Contribution

It provides a comprehensive, data-driven assessment of roof greening priorities and benefits at a city scale, informing sustainable urban development strategies.

Findings

85.3% of buildings have urgent roof greening demand

Green roofs could increase greenspace exposure by ~61%

Economic benefits amount to hundreds of millions HK$ annually

Abstract

Greenspaces are tightly linked to human well-being. Yet, rapid urbanization has exacerbated greenspace exposure inequality and declining human life quality. Roof greening has been recognized as an effective strategy to mitigate these negative impacts. Understanding priorities and benefits is crucial to promoting green roofs. Here, using geospatial big data, we conduct an urban-scale assessment of roof greening at a single building level in Hong Kong from a sustainable development perspective. We identify that 85.3\% of buildings reveal potential and urgent demand for roof greening. We further find green roofs could increase greenspace exposure by \textasciitilde61\% and produce hundreds of millions (HK\$) in economic benefits annually but play a small role in urban heat mitigation (\textasciitilde0.15\degree{C}) and annual carbon emission offsets (\textasciitilde0.8\%). Our study offers a comprehensive assessment of roof greening, which could provide reference for sustainable development in cities worldwide, from data utilization to solutions and findings.