Social value of urban NbS in Essen, Germany

Essen is a city in the Ruhr region of Germany, characterised by post-industrial urban landscape with ongoing regeneration. It has a high population density typical of German urban areas..

To estimate the social value of nature-based solutions implemented in urban areas through willingness-to-pay assessment, enabling comparison of benefits against implementation and maintenance costs to inform investment decisions.

Challenges addressed

The project mainly tackles environmental management in a densely built, post-industrial city.

Costs of NbS

The 240 ha Krupp Park was restored to improve environmental conditions, open the area for recreation and extend the city’s urban nature network. Implementation cost about EUR 7.6 million, and maintenance is estimated at about EUR 1.24 million per year. Over a 40-year lifetime, total costs come to about EUR 36.3 million (2023 prices, 3% discount rate).

Potential impacts/benefits

The restored park gives residents new space for recreation close to home, supporting health and wellbeing. It also supports biodiversity and links habitats across the city’s urban nature network. Residents value these benefits at about EUR 50.3 million per year (2023 prices).

Benefit–cost ratio

 Over a 40-year lifetime at a 3% discount rate, these benefits give a BCR of 32: the park returns far more to residents than it costs to create and maintain.

• Application of benefit transfer valuation method based on meta-analysis of 60 primary valuation studies. 
• Collection of socio-economic data including GDP per capita and population density. 
• Estimation of implementation costs and annual operational costs by intervention type. 
• Calculation of net present value and benefit-to-cost ratio using 3% discount rate over 40-year lifetime.
• Sensitivity analysis testing alternative discount rates and cost assumptions.

 None available

Study overview

Essen participated in a European-wide assessment of nature-based solutions (NBS) social value across 85 urban interventions spanning 13 countries. The study evaluated the aggregate social value generated for urban residents through implemented NBS, using benefit transfer methods based on willingness-to-pay meta-analysis.

The research analysed 60 NBS projects where cost data was available, with total implementation costs of US5.39 billion across all projects.Average annual maintenance costs were estimated at US 14.7 million, while median annual maintenance costs were US$ 1 million per project. These costs varied substantially by intervention type, ranging from street tree plantings and green walls to larger infrastructure such as parks, green corridors and sustainable urban drainage systems.

For Essen and comparable German sites, a benefit-to-cost ratio (BCR) analysis was conducted using a 3% discount rate over a 40-year project lifetime. Across all 60 projects assessed, 39 interventions (65%) demonstrated a BCR above 1, indicating positive social returns on investment when valuing benefits to residents. This includes health and wellbeing improvements, quality of life enhancements and other social values captured through citizen preference studies.

The valuation methodology applied a meta-analytic value transfer function accounting for socio-economic factors including GDP per capita and population density. The approach captured direct use values, indirect use values and non-use values of urban nature. Projects classified as 'multiscapes' incorporating multiple nature types showed higher estimated per-hectare values.

Sensitivity analyses confirmed the robustness of findings. At a 5% discount rate, the percentage of projects with positive net present value remained stable, while at 1% it increased to 67.3%. Even with a 50% increase in operational costs, 61.67% of interventions retained positive NPV.

The study demonstrates that urban NBS generate measurable social value for residents that can justify public and private investment. For cities like Essen, this evidence supports integrating NBS into urban redevelopment plans, potentially accessing municipal health and wellbeing budgets, real estate development funding or NGO contributions alongside traditional public financing.

Estimating the social value of nature-based solutions in European cities