Cost and benefits
Information on the costs and benefits as well as the long-term effectiveness and efficiency of green infrastructure are crucial when making decisions about whether or not to implement a green, hybrid or grey solution or as a means to promote green infrastructure’s ‘value for money’ within policies and to the general public.
Benefits of green infrastructure
The benefits generated through GI extend across multiple sectors and can have positive impacts for society, the environment (including for biodiversity) and the economy. These commonly accrue over an extended period of time and sometimes only emerge after a given number of years (e.g. benefits for biodiversity). Examples include:
- Economic benefits: outputs of food and natural resources, indirect and direct increases in employment, saved costs from increased energy or water efficiency, reduced costs from environmental damage, increased property values, and reduced public health costs...
- Environmental benefits: provisioning of habitat for biodiversity, air and water quality regulation, climate mitigation…
- Societal benefits: increased recreation opportunities, physical and mental health benefits, improved social cohesion, climate adaptation...
Many of these benefits are classified as ecosystem services, and are outlined in the Common International Classification of Ecosystem Services (CICES). The specific types and value of benefits generated by a given GI project depends on the design, implementation and local context of the project.
Costs associated with green infrastructure
Unlike the benefits of GI, associated costs are much more easily measurable. There are two main types of direct costs associated with GI projects, with the most significant usually being the one-off (i.e. incurred only once) costs for identifying, mapping, planning, creating, and restoring green infrastructure. The other major associated cost category is for ongoing maintenance and monitoring of the impact of GI projects, which can extend across the lifetime of the project.
Measuring the costs and benefits of GI
There is a large evidence base qualitatively describing the benefits of GI, and a smaller but robust evidence base quantifying the associated economic, social, and environmental costs and benefits. Costs are usually more straightforward to assess than benefits, as benefits are multifaceted, need to be assessed over long timeframes, and are often indirect and influenced by complex ecosystem services. There is no single accepted methodological approach for quantifying benefits. Instead there exists a variety of tools and approaches that depend on local data availability, types of projects, and types of benefits targeted. Methods to assess the benefits of GI often focus on valuing the generated ecosystem services. In cases in which the costs and benefits of green infrastructure projects have been quantified, benefits tend to significantly exceed the involved costs (see examples below).
Illustrative case studies