Module costs, benefits, financing

osts, benefits, and financing of blue-green infrastructures represent the socio-economic dimension of the BGCC Toolbox.
They often pose challenges that arise from the specific configuration of these infrastructures. Climate-adapted urban development—based on the deployment of blue-green-grey infrastructures—is not only a planning and technical challenge but, above all, a socio-economic transformation task.
Blue-green-grey infrastructures—comprising water-related (blue), vegetation-based (green), and technical (grey) systems—offer numerous benefits, such as improved flood prevention, reduced urban heat, enhanced biodiversity, and increased quality of urban life. However, their practical implementation involves socio-economic questions that must be carefully considered in the planning and financing processes.
The specific costs of such infrastructure projects can vary significantly and depend largely on the technical design and local conditions of each case. In general, two types of costs can be distinguished in connection with the introduction of blue-green infrastructures:

  1. Transaction costs, which are often higher compared to traditional centralized drainage systems and arise during the planning, coordination, and stakeholder alignment.
  2. Replacement and supplementary costs, associated with retrofitting or augmenting existing urban drainage systems with blue-green infrastructure elements.

It is also important to differentiate between microeconomic and macroeconomic perspectives:

  • From a microeconomic perspective, the focus is on the costs (and benefits) at the level of individual plots or infrastructure components, involving property owners, users, and local stakeholders. Here, specific interests frequently emerge, requiring negotiation and cooperation among actors.
  • From a macroeconomic perspective, blue-green infrastructures can affect land and property values, neighborhood quality of life, and the public good. Their broader effects—such as improved quality of life, climate adaptation, and increased resilience—justify public investment, while also raising questions of fair cost-benefit distribution. Put simply: Who pays and who benefits?

The widespread implementation of blue-green infrastructure changes and redistributes cost structures and responsibilities. For example, maintenance costs previously assigned to the urban drainage department might reappear as maintenance expenses for green spaces under the parks department.
Climate-adapted urban development through blue-green infrastructures goes far beyond technical issues. It requires an integrative approach that considers not only ecological but also economic and social dimensions—thereby laying the foundation for a sustainable and socially balanced urban transformation.

The BGCC Toolbox offers the following instruments, which have repeatedly proven their value in practical application:
  • netWORKS 4 Info Cards: A tool to support participatory planning processes (more information available at: https://networks-group.de/de/networks-4/infokarten.html)
  • Constellation Analysis: A method for developing cooperation models in the implementation of blue-green-grey infrastructures (Schramm, Engelbert; Trapp, Jan Hendrik; Stein, Christian; Rauchecker, Markus (2023): Establishing and Maintaining Blue-Green-Grey Infrastructures for Municipal Climate Adaptation. Case Studies, Constellations, and Cooperation Management. Published by the research consortium netWORKS. Berlin (netWORKS Papers, 39). Available online at: https://repository.difu.de/jspui/handle/difu/583721; originally developed by: Schön, S., S. Kruse, M. Meister, B. Nölting, D. Ohlhorst (2007): Handbook of Constellation Analysis: An Interdisciplinary Bridge Concept for Sustainability, Technology, and Innovation Research. Oekom, Munich 2007.)
Example of a constellation analysis (Schramm et al., 2024, p. 23)
Example of a constellation analysis (Schramm et al., 2024, p. 23)