Book chapter

Soon to be published online, you can already read the abstract of a new book chapter titled 'The impacts of urban green infrastructure on water and energy resources: Lessons from and the need for integrated studies'. I wrote this with my colleague Joanne Vinke-de Kruijf, and it will feature in Urban Green Spaces - New Perspectives for Urban Resilience, with as editors C. M. Monteiro, C. Santos, C. Matos, A. B. Sá. from IntechOpen.

Abstract

Green infrastructure (GI) can bring both water and energy benefits to urban environments. Yet, installation and maintenance may incur additional water and energy demand. Despite the wide range of GI reviews, insight is lacking of to what extent and how existing empirical and modelling studies quantify GI impacts on urban water and energy resources in an integrated manner. We systematically reviewed 21 studies that quantify GI’s impacts on both water and energy and 86 studies that focus on green infrastructure. We investigate the parameters and quantification methods that are used for the most promising type of urban GI (green roofs) in-depth, and identify research gaps and develop a research agenda. Our review shows that relatively few studies quantify impacts on both water and energy resources. Moreover, existing studies tend to focus on positive impacts, such as heat abatement, energy savings, and runoff reduction, with little attention for negative impacts, such as energy demands or emissions. Considering water and energy impacts, green roofs are the most promising urban GI. They are easy to install and maintain in dense urban areas, reduce energy demand, and require little water. We find that all GI’s impacts highly depend on local climate and GI’s design, especially structural and storage parameters, vegetation, and soil depth. Green roof performance mainly depends on vegetation, soil moisture, substrate characteristics and depth; and different combinations of these factors can lead to important tradeoffs for water and energy resources. The results call for extending and improving life cycle assessments, especially by quantifying negative impacts such as the energy costs of irrigation, and optimizing the identified tradeoffs between the potential beneficial impacts of GI and their negative water and energy impacts.