Green Roof Subsidy - Rotterdam

Since 2008, citizens can apply for a green roof subsidy from the city of Rotterdam in the Netherlands to partially cover the otherwise large costs of installing such interventions. The goal of the program is to achieve a total of 800.000 square meters of multi-functional roofs with greenery, water retention systems, and solar panels by 2030. In order to be eligible for the subsidy, roofs must be able to retain 30 ml of water per square meter. In return, building owners (private individuals, home owners associations, organisations, contractors and property owners) can get up to €500 for every cubic meter of water collected through the green roof. The city also pushes the construction green roofs on top of municipal property. By increasing the total surface of roofs covered with soil and greenery, the municipality aims to enhance water retention capacities as well as heat absorption during heatwaves. Green roofs, by acting as isolators, also increase the overall durability of the underneath building, and the new green spaces offer opportunities for various uses, such as gardening and food production. The access to subsidies is conditional upon the selection of plants which include native and non-native species particularly beneficial to biodiversity.

Overview

Type of instrument:

Economic and fiscal instruments›Payments as rewards/for ecosystem services, subsidies, incentives

Challenges addressed

Water management (e.g. reuse)
Heat stress and heat island effect
Air quality
Nature appropriation / stewardship
Reconnection to the biosphere / environmental education
Human health, comfort and well-being

Consideration of nature-based solutions:

The goal of the subsidy program is to achieve a total of 800.000 square meters of multi-functional roofs with greenery, water retention systems, and solar panels by 2030. In 2019, the City introduced a color system to differentiate types of green roofs according to the ecosystem and other services they provide: Green roofs provide greening and increased biodiversity in the city, blue roofs store water and ensure delayed drainage, yellow roofs generate sustainable energy, red roofs house social functions and look after social cohesion, orange roofs are used for mobility, purple roofs are residential roofs and grey roofs harbor technical functions. Added value is created by combining various different functions or colours: so called golden combinations. Ultimately, the program provides an integrated approach to roofs, ensuring they deliver ecological, social and climate benefits.

Targeted (peri-)urban areas:

Green areas for water management

External building greens

Urban green space connected to grey infrastructure

Good practice characteristics:

Support multifunctional NBS

Potential to be replicated / upscaled

Innovative

Policy business case

Governance

Government body/bodies

Initiating body:

City of Rotterdam

Instrument implementation:

Type of involvement:

As only a minority of buildings in Rotterdam are owned by the city, the ownership and use of roofs largely lies with private individuals, home owners associations, organisations, contractors and property owners. Hence, the involvement of these stakeholders is key to the success of the program. Once a roof has been greened, house owners and residents become co-responsible in maintaining the roof. These efforts are supported by awareness raising campaigns, an online tool to support information dissemination and decision-making, and engagement activities to increase participation in the program (more details provided under 'lessons learned').

Type of non-governmental actors involved:

Implementation of NBS (e.g. with government funds)

Targeted actors:

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

Private: household, real estate developer, business , financial

Citizens or community groups (CBOs), NGOs

Financing

Sources of funding:

Public local authority’s budget

European Union funds

Budget:

Unknown

Details about instrument financing:

The municipality provides the funds for the subsidy program. Additional funds are provided by the European Union through the LIFE@Urban Roofs project, which is part of European LIFE program for environment and climate action. To green a roof of 750 square meters, the estimated costs are EUR 4,400 with a municipal subsidy of EUR 1,900.

Monitoring, evaluation and impacts

Achieved outcomes and impacts:

In 2018, 10 years after the start of the subsidy program, 360,000m2 of green roofs and 168.000m2 of solar panels were installed throughout the city on rooftops. In addition, citizens showed great interest in the the accompanying awareness raising campaigns: In 2018, 20,000 people visited the Rotterdam Roof Days.

Success factors and lessons learned:

A sustainable maintenance of the green rooftops requires ownership by the local community. To enhance ownership, continuous efforts by the city of Rotterdam have proven useful. For example, the city of Rotterdam has identified front runners who have successfully greened roofs as well as sample projects to help communicating the benefits of green roofs. To further encourage building owners to retrofit their roofs, the city has also created an interactive online tool. The tool provides information about the load-bearing capacity of a specific roof, the costs and potential subsidy as well as different options for greening it and for installing solar panels. To raise awareness about the potential of green roofs, the city celebrates the annual The Rooftop Days festival. The festival includes an extensive program of tours, concerts, exhibitions, and dinners on selected green roofs. In 2022, the city additionally organised a Rooftop Walk for citizens. The walk covered a route of different rooftops within the city centre and connected iconic buildings. Challenges remain as some communities may be showing more ownership than others. In particular in vulnerable communities, it can be difficult to ensure a high degree of onwership for the maintenance of green roofs. Here, awareness raising campaigns that are tailored to the needs of particular groups can be helpful.

Sources and further information

References

List of references:

Gemeente Rotterdam (2021). Groene Daken. Available at: https://www.rotterdam.nl/wonen-leven/groene-daken/ (Retrieved on 17.07.2022)

Velazquez, Aramis (2022). Inside Rotterdam’s Quest to Green 10 Million Square Feet of Rooftops. https://www.greenroofs.com/2022/06/02/inside-rotterdams-quest-to-green-10-million-square-feet-of-rooftops (Accessed: 16 July 2022).

Gemeente Rotterdam (2022). LIFE@Urban Roofs. https://www.rotterdam.nl/wonen-leven/urban-roofs/ (Accessed: 16 July 2022).

Gemeente Rotterdam (2020). Rotterdam Weather Wise Urgency Document. https://www.rotterdam.nl/wonen-leven/rotterdams-weerwoord/Urgentiedocument-2020_EN.pdf (Accessed: 16 July 2022).

Kerssen, A. (2021). Green Roofs and Living Walls in the Netherlands. Living Roofs. Available at: https://livingroofs.org/green-roofs-in-the-netherlands/ (Retrieved on 17.07.2022)

Gemeente Rotterdam (2021). Subsidie voor opvang regenwater en meer groen. Available at: https://www.rotterdam.nl/wonen-leven/subsidie-klimaatadaptatie/ (Retrieved on 17.07.2022)

Gemeente Rotterdam (2019). Working towards a Rotterdam Roof Landscape Programme for Multifunctional Roofs. https://www.rotterdam.nl/english/multifunctional-roofs/2019_Working-Towards-a-Rotterdam-Roof-Landscape-Programma-for-Multifunctional-Roofs.pdf (Retrieved on 17.07.2022)

Further documents

Weblinks:

https://www.rotterdam.nl/wonen-leven/groene-daken/

https://www.youtube.com/watch?v=w2ugPQmgvkE

Photos

@CHUTTERSNAP en Unsplash