Localizing and prioritizing roof greening opportunities for urban heat island mitigation: insights from the city of Krefeld, Germany

Abstract

Context Climate change may increase the frequency, intensity, and occurrence of urban heat islands (UHI) in cities worldwide, often with harmful impacts on citizens. Strategic planning and implementation of multifunctional green roofs promises to help mitigating UHI effects, but cities often lack up-to-date scientific understanding of best-suited locations. Objectives The aim of this paper is to develop and apply a socio-ecological approach to explore and prioritize present and prospective opportunity spaces for roof greening based on remote sensing data to mitigate UHI effects. Methods The city of Krefeld, Germany, serves as a case study. The research design consists of three steps, applied to the conditions of 2019 and a 2030 scenario: (i) Examining residents’ vulnerability to heat, (ii) Assessing existing green roofs and potentials for greening, and (iii) Prioritizing opportunity spaces for roof greening to reduce UHI effects. Results Findings showed that the area of high vulnerability due to combined high heat exposures and densities of sensitive residents in Krefeld accounts for almost 300 hectares in 2019 and may triple until 2030. More than 90% of evaluated horizontal roofs have no vegetation cover. Highest priority for roof greening is attributed to 59 ha and 113 ha of roofs in 2019 and 2030, respectively. Conclusions The findings can inform strategic roof greening efforts for climate adaptation, e.g. for the extension of cadasters, and facilitate communication to increase understandings, public and policy support, and implementation.

Feasibility study of geosynthetic vegetation substrate for hard-surface ecological restoration part 2: Biodiversity and environmental effects

“…Owing to the plant cover, the vertical green wall can not only insulate indoor environments against outdoor noise but also provide heat insulation. Consequently, the use of energy-consuming equipment such as air conditioners and heaters is expected to reduce, lowering the cost of air conditioning inside the building and effectively saving energy [1].…”

Butterfly community composition within a tropical urban landscape is influenced by habitat type and temperature

“…Anthropogenic impacts in tropical urban systems, such as increasing land‐use change, have continued to degrade key ecosystems (Shellberg et al, 2016), with tropical systems such as South America, southeast Asia and central Africa experiencing the most degradation (Baranowski & Bharti, 2023; Hansen et al, 2013). In the tropics, increasing ecosystem degradation with rising urbanisation rates is modifying ecosystem services and regional/local climates (Brenner et al, 2023; Fang et al, 2023; Foley et al, 2005; Okoro et al, 2023), having the potential to heavily impact habitat availability and resource use by native species (Baranowski & Bharti, 2023; Haddad et al, 2015; Oeser et al, 2023; Okoro et al, 2023). Rising environmental perturbation caused by land conversion is expected to impact many native urban species by modifying or removing their habitats and resources.…”

Environmental heterogeneity across habitats within a tropical urban landscape influences butterfly community compositions

“…Anthropogenic impacts in tropical urban systems, such as increasing land-use change, have continued to degrade key ecosystems (Shellberg et al, 2016), with tropical systems such as South America, southeast Asia and central Africa experiencing the most degradation (Hansen et al, 2013; Baranowski and Bharti, 2023). In the tropics, increasing ecosystem degradation with rising urbanisation rates is modifying ecosystem services and regional / local climates (Foley et al, 2005;Brenner et al, 2023;Fang et al, 2023), having the potential to heavily impact habitat availability and resource use by native species (Haddad et al, 2015; Baranowski and Bharti, 2023;Oeser et al, 2023;Okoro et al, 2023). Rising environmental perturbation caused by land conversion is expected to impact many native urban species by modifying or removing their habitats and resources.…”