Calculation tool for water storage solutions - Eindhoven

The city of Eindhoven in the Netherlands provides all building projects with a digital calculation tool to calculate the amount of storage needed to fulfill a 2019 requirement - 'Destination plan water storage 2020'. The aim is to stimulate the greening of building projects and therefore the whole city. Building projects are able to freely decide what kind of water storage method will be used to fulfill the requirement, but the destination plan dictates that the greener the total building solution will be (including greening the surrounding area), the lower the amount of water that needs to be stored. The tool provide calculations as well as practical examples on how to use green methods of be store water. The results of the tool serve as a direct input for the permitting process. In doing so, three goals are achieved (1) increased green roofing on new buildings to make the municipality more climate resilient; (2) more green area’s/façades in the city on privately owned plots; and (3) easier (but mandatory) permit process concerning stormwater storage solutions. The measures contribute not only to water management (i.e. reducing pressure on the sewage system), but also help combat heat stress, improve air quality and benefit biodiversity. Since the introduction of the tool in 2019, about 70% of new building projects include green roofing, as compared to circa 10% before the tool.

Overview

Type of instrument:

Knowledge, communication and innovation instruments›Knowledge and/or innovation

Challenges addressed

Water management (e.g. reuse)
Green space management (e.g. accessibility)
Watershed restoration/water quality
Flood risk: pluvial and fluvial / soil permeability
Heat stress and heat island effect
Air quality

Consideration of nature-based solutions:

The tool directly stimulate the use of a range of nature-based solutions, which both address water management challenges as well as urban health challenges (e.g. heat stress and poor air quality). Eligible measures include, for example: reducing paved surface areas and greening areas; making a green roof; rerouting water to be stored, preferably in a swale type solution; realize extra measures in the building plan with green facades and waterbarrels. Benefits of these measures extend to the soil health, biodiversity, and reduced energy investments in water purification due to reduced water quantities entering the wastewater plant.

Targeted (peri-)urban areas:

Green areas for water management

External building greens

Good practice characteristics:

Sustainable in the long-term

Locally appropriate

Governance

Government body/bodies

Initiating body:

Eindhoven City Council

Instrument design:

Details about how the instrument was designed:

Over the last two decades, the municipality of Eindhoven has increasingly realized that climate adaption cannot be done on its own land, as around two-thirds of the city area is privately owned. This means that the municipality recognized importance of involving citizens to jointly tackle the climate challenge. One of the ways to get people to act is subsidizing, while another is to force those who are building to include adaptation measures. The politicians agreed on this vision and commissioned the design of the ‘Rekentool Klimaatopgave’ by Atelier GroenBlauw.

Involvement of non-governmental actors:

Private sector, corporate, business

Type of actor involvement:

Co-planning or co-design of instrument (e.g. boards, advisory role)

Instrument implementation:

Type of involvement:

In the Netherlands, requirements are a common instrument to motivate action by other parties. However, this requires that the responsible municipality follow a precise procedure and exert it’s legal control in order to implement the legal obligation as envisioned. In this case, a destination plan was developed by the city of Eindhoven and provides the legal basis for the tool. The tool itself is available on a website of the municipality and is to be used by all parties having to fulfill the requirement within building projects.

Type of non-governmental actors involved:

Use and application of the calculation tool

Targeted actors:

Public sector institution (e.g. school or hospital)

Private: household, real estate developer, business , financial

Citizens or community groups (CBOs), NGOs

Financing

Budget:

Less than 50 000 €

Details about instrument financing:

Eindhoven municipality has financed the tool since 2019 from the tax of sewer management. Every year, the municipality determines the amount of this tax of sewer management because of the use by the citizens of all collective (waste)water facilities.

Monitoring, evaluation and impacts

Achieved outcomes and impacts:

Until January 2023, the municipality has received 1096 building applications with a stormwater storage obligation. The tool brings also more awareness for the sustainable use of rainwater. More and more other ideas are presented for the re-use of rainwater like the irrigation of trees or green fields, creating water storage under sport fields, making waterbarrels for flushing toilets.

Success factors and lessons learned:

The success of the tool comes from it’s simple layout and the direct link to the implementation of the regulations. The applicant can easily fill in a digital form and directly calculate the effects of the chosen solution. He is also automatically stimulated to choose green methods and provided with good practice examples, which can serve as inspiration. The results help the user to develop a clear and sustainable plan for effective water storage.

Sources and further information

References

List of references:

https://www.eindhoven.nl/bouwen/klimaatrobuust-bouwen?search=waterberging

Further documents

Weblinks:

https://www.ruimtelijkeplannen.nl/web-roo/transform/NL.IMRO.0772.80348-0301/pt_N…

https://rekentool.eindhovenduurzaam.nl/

https://www.eindhovenduurzaam.nl/klimaatadaptatie/wat-kun-je-zelf-doen

Photos

@M.Bosch