1. General information
Location and description of the intervention
City or FUA
Hamburg
Region
Europe
Native title of the NBS intervention
Dachbegrünung in Hamburg
Short description of the intervention
Due to the challenges caused by climate change, Hamburg decided to become greener and developed a comprehensive, pioneering green roof strategy. The strategy aims at creating 100 hectares of new green walls by 2019 by providing grants for building owners for greening roofs and offering them rain water fee reduction owing to the rain water retention of the green roofs. (Reference 1) The financial support offered until the end of 2019 is 3 million EUR. (Reference 2) The services offered by the city in this plan consist of four pillars: promotion (financial incentive), dialogue, regulation, and scientific support. (Reference 7)
Address

Hamburg
Germany

Location
The NBS is a city-wide initiative, the GIS point marks the centre of the city
Total area
1000000.00m²
NBS area
1000000.00m²
Type of area before implementation of the NBS
Building
Website of the intervention
http://www.hamburg.de/gruendach
Timeline of intervention
Start date of the intervention (planning process)
2014
Start date of intervention (implementation process)
2015
End date of the intervention
2019
Present stage of the intervention
Completed
Goals of the intervention
- improving the quality of open green city spaces
- encouraging space efficient leisure areas
- improving the city’s rainwater retention capacity
- increasing biodiversity
- improving the city climate (reduction of the heat island effect)
- improving the liveability of the rapidly growing city (Reference 2, 3 and 7)
Quantitative targets
The description on the webpage of the European Climate Adaption Platform writes: "The goal is to plant a total of 100 hectares of green roof surface with plants and flowers in the metropolitan area by 2020, the equivalent of double the surface of ‘Planten un Blomen’ city park (45 hectares). New residential constructions alone provide a 44 hectare green roof potential over 5 years, new business constructions provide an additional potential of 66 hectares. The city’s ambition is to have 20% of the green roofs on new buildings to be made available to residents or employees for recreation, in the form of sports fields and parks, or as gardens in shared use by the housing community" (Reference 2).
Monitoring indicators defined
- number of green roofs
- area of green roofs
- % of the green roofs on new buildings to be made available to residents or employees for recreation (Reference 2)
Sustainability challenge(s) addressed
Climate action for adaptation, resilience and mitigation (SDG 13)
Climate change adaptation
Water management (SDG 6)
Flood protection
Stormwater and rainfall management and storage
Green space, habitats and biodiversity (SDG 15)
Habitat and biodiversity conservation
Green space creation and/or management
Environmental quality
Air quality improvement
Regeneration, land-use and urban development
Regulation of built environment
Promote natural styles of landscape design for urban development
Health and well-being (SDG 3)
Enabling opportunities for physical activity
Creation of opportunities for recreation
Economic development and employment (SDG 8)
Real estate development
Climate change adaptation: What were the goals of the NBS?
Reduce the impacts of climate risks events on urban places and communities
Climate change adaptation: What activities are implemented to realize the conservation goals and targets?
Increase or improve urban vegetation cover to help reduce outdoor temperature
Create or improve outdoor spaces to help people escape from urban heat
Implement green walls or roofs to lower indoor temperature and provide insulation
Habitats and biodiversity conservation: What types of conservation goals are / were defined for the NBS intervention?
Ecosystem-focused
Habitats and biodiversity conservation: What activities are implemented to realize the conservation goals and targets?
Protect and enhance urban habitats
Preserve and strengthen existing habitats and ecosystems
Promote environmentally-sound development in and around protected areas
Create new habitats
What types of restoration goals are / were defined for the NBS intervention?
No information provided regarding the goals of the intervention.
Implementation activities
For fulfilling the ambitions of the Green Roof Strategy, the city combines promotion, dialogue, regulation and scientific support:
- Promotion: providing subsidies for building owners (private and public) for installing green roofs voluntarily as refurbishment or as an element of a new building. Citizens or companies can apply for the funds if they voluntarily plan to install at least 20 sqm of green roofing with a soil layer of at least 8 cm in depth. (Reference 8)
- Communication and dialogue: organizing an awareness raising campaign (“On Your Roofs, Get Set, Green!”), starting a dialogue with local politicians, authorities, architects, engineers and economists on the topic.
- Regulation: incorporating or enhancing the strategy into legally binding instruments like the Hamburg Building law, the wastewater law, planting regulations on structural systems and land-use plans
- Scientific support: HafenCity University supports the program by evaluating international findings on green roofs, developing recommendations for Hamburg’s green roof construction, and collecting data on water retention and the water management effectiveness of green roofs. As part of the project, the city of Hamburg published a comprehensive guide about how and why to implement green roofs. (Reference 1, 2)
Type of NBS project
Creation of new green areas
Knowledge creation and awareness raising
Strategy, plan or policy development
NBS domain and interventions
Ecological domain(s) where the NBS intervention(s) is/are implemented
Nature on buildings (external)
Green roofs
Parks and urban forests
Pocket parks/neighbourhood green spaces
Green areas for water management
Sustainable urban drainage systems
Type of Green Roof
Extensive Green Roof: depth 3 - 5 inches; plants: Mosses, Sedums, Succulents, Herbs and few Grasses; Low maintenance and costs
Please specify the number of plots or allotment gardens
unknown
What is the level of innovation / development of the NBS related to water management?
Low: Simple rain water collection intervention (rain garden, local seepage pit) or simple permeable areas
Vegetation Type
Grass
Shrubs
Flower beds
Garden beds
Other
Amenities offered by the NBS
Sports areas and equipment
Services
Expected ecosystem services delivered
Regulating services
Local climate regulation (temperature reduction)
Air quality regulation
Flood regulation
Habitat and supporting services
Maintenance of genetic diversity
Cultural services
Aesthetic appreciation
Recreation
Mental and physical health and wellbeing
Scale
Spatial scale
Meso-scale: Regional, metropolitan and urban level
Sub-microscale: Street scale (including buildings)
Beneficiaries
Primary Beneficiaries
National-level government
Local government/Municipality
Private sector/Corporate/Company
Researchers/University
Citizens or community groups
Please specify other local relevant strategy
Nature conservation act: "in accordance with the Nature Conservation Act green roofs are considered a possible measure in the context of compensating building impact on nature" (Reference 2).
Hamburg Building law, the wastewater law (Reference 1, 2)
Governance
Governance arrangements
Co-governance with government and non-government actors
Non-government actors
Private sector/Corporate/Business
Researchers, university
Citizens or community groups
Please specify the roles of the specific government and non-government actor groups involved in the initiative
"The Hamburg Ministry for Environment and Energy is providing financial support for the creation of green roofs to the sum of € 3 million until the end of 2019 [...] Within the city a stakeholder group was established including housing estate companies, constructors, landscape architects and urban planners. Parallel to the dialogue with other cities this group was involved in defining the incentive programme. The group has remained active since and during its bi-annual meetings the Green Roof Strategy is evaluated by the working group" (Reference 2).
Hamburg is the first German city that has developed a comprehensive green roof strategy. Furthermore, the German Federal Ministry for the Environment, Nature, Building and Reactor Safety supports the strategy as a pilot project within their programme “Measures for adaptation to climate change” (Reference 2).
Key actors - initiating organization
Local government/municipality
Land owners
Public space owned by the city
Key actors - Other stakeholders involved (besides initiating actors)
National government
Local government/municipality
Researchers/university
Citizens or community group
Land owners
No information found
Participatory methods/forms of community involvement used
Dissemination of information and education
Joint implementation (e.g. tree planting)
Policy drivers
NBS intervention implemented in response to an Regional Directive/Strategy
Unknown
NBS intervention implemented in response to a national regulations/strategy/plan
Yes
Please specify the national regulations/strategy/plan
The description of the project writes: "The current Green Roof Strategy combines the urban development policy objectives of sustainable area development with the objectives of adaptation to global warming and climate change [...] in accordance with the Nature Conservation Act green roofs are considered a possible measure in the context of compensating building impact on nature" (Reference 2).
NBS intervention implemented in response to a local regulation/strategy/plan
Yes
Please specify the "local regulation/strategy/plan"
The description of the project writes: "The current Green Roof Strategy combines the urban development policy objectives of sustainable area development with the objectives of adaptation to global warming and climate change. In Hamburg binding green roof regulation has been incorporated in many land-use plans for 20 years. Also, in accordance with the Nature Conservation Act green roofs are considered a possible measure in the context of compensating building impact on nature. From 2020 onwards Hamburg plans to have green roofs to be compulsory by law. The city of Hamburg also regularly reviews its green roof legislation in particular with regards to the ecological quality standards for the roofs. Specifically, when updating Hamburg’s regulations next time, the aim is to increase the standard green roof thickness up to 12-15 cm" (Reference 2).
Mandatory or voluntary intervention
Voluntary (spontaneous)
Intervention is mandatory
Spatial planning law
Environmental regulation
Building regulation
Please specify other type of voluntary intervention
The implementation of the green roofs is voluntary, however: "From 2020 onwards Hamburg plans to have green roofs to be compulsory by law. The city of Hamburg also regularly reviews its green roof legislation in particular with regards to the ecological quality standards for the roofs. Specifically, when updating Hamburg’s regulations next time, the aim is to increase the standard green roof thickness up to 12-15 cm" (Reference 2).
Enablers
Presence of specific city-level GI/NBS vision/strategy/plan - mentioned in connection to the project
Yes
Please specify
Green roofs in Hamburg are implemented in response to the "Green Roof Strategy" of the city that is an NBS strategy of Hamburg to increase the number and area of green roofs in the inner city (Reference 2).
Presence of specific city-level GI/NBS section/part in a more general plan - mentioned in connection to the project
Yes
Please specify the general plan with GI/NBS section
In 2011, Hamburg was chosen to be the Green Capital of the EU (Reference 2). This programme aims to promote and award commitment and innovation to resolve environmental challenges in cities (Reference 5). The Green Roof Strategy is in line with the green strategy that the Green Capital Award projected and it is mentioned in the selective report of the city ("Hamburg: European Green Capital: Five years on") being published in 2016 (Reference 6).
If there is a relevant strategy or plan, please specify the theme / type of the plan.
City specific green space strategy or plan
Municipal / city level environmental plan or programme
Other
Please specify other vegetation type
Mosses, perennials (Reference 4)
-new green walls (Reference 1)
green roof surface with plants and flowers (Reference 2)
Presence of city network or regional partnerships focused on NBS - mentioned in connection to the project
Yes
Please specify
The description of the project writes: "Hamburg is using a wide range of networks and cooperation with other cities to present itself as a climate action centre at regional, national, European and international level. The experience gained in this process is used in its own response to climate change. When developing the incentive programme for green roofs, Hamburg involved other cities in a search for good practice and soliciting for feedback on draft versions of the incentive programme. Based on this interaction with other cities Hamburg decided to have their financial incentive program based on surface and thickness of the green roofs instead of water retention capacity as is the case in most other programs in other cities. This decision led to constructors not only focusing on water retention but also considering other benefits that green roofs may have such as in the context of biodiversity and space utilization" (Reference 2).
Presence of GI / NBS research project - mentioned in connection to the project
Yes
Please specify
The description of the project writes: "it has been questioned whether green roofs indeed provide the needed water retention capacities especially with a heavy storm water event. The concern is that support for this only stems from small scale experimental settings and that real and large roofs would not provide adequate retention service. To solve the matter HafenCity University is currently researching this question. Further, when initiating the Green Roof Strategy it was challenged whether Hamburg was having sufficient flat roofs to be able to succeed with the strategy. GIS-based research solved this question, showing that over 40% of the cities roofs are flat and suitable for greening".

In addition, Hamburg’s Ministry for Environment and Energy and the Harbour City University receive € 300,000 in federal grants on expenditure basis from the German Ministry of the Environment under a funding programme supporting local activities for the adaptation to climate change. This federal grant on an expenditure basis is used to pay a full time communications officer and a part-time HafenCity researcher for 2-3 years" (Reference 2).
Subsidies/investment for GI / NBS in the city - mentioned in connection to the project
Yes
Please specify
The description of the program writes: "Hamburg’s Ministry for Environment and Energy invests ca. € 500,000 of its own resources for the implementation of the overall Green Roof Strategy, including efforts in all four areas of activity: promotion/support, dialogue and communication, scientific support, and policy/regulation. It also includes a full-time employee based at the Ministry.

In addition, Hamburg’s Ministry for Environment and Energy and the Harbour City University receive € 300,000 in federal grants on expenditure basis from the German Ministry of the Environment under a funding programme supporting local activities for the adaptation to climate change. This federal grant on an expenditure basis is used to pay a full time communications officer and a part-time HafenCity researcher for 2-3 years" (Reference 2).
Co-finance for NBS
Yes
Co-financing governance arrangements
Unknown
Was this co-governance arrangement already in place, or was it set up specifically for this NBS?
Unknown
Financing
Total cost
€2,000,000 - €4,000,000
What is/was the Cost/Budget (EUR) of the NBS or green infrastructure elements?
3,000,000 (Reference 2)
What are the total amount of expected annual maintenance costs?
unknown
What is the expected annual maintenance costs of the NBS or GI elements?
unknown
Please specify cost savings
unknown
Please specify total cost (EUR)
3 million EUR untill 2019 is provided by the municipality of Hamburg. For each individual project within the programme, the project can receive up to 60% funding from the municipality, with the remainder being funded by whoever is implementing the green roof(s). (Reference 2)
Source(s) of funding
Public regional budget
Public local authority budget
Type of fund(s) used
Direct funding (grants, subsidies, or self-financed projects by private entities)
Tax exemption
Non-financial contribution
Unknown
Business models
Risk reduction model
Green densification model
Please specify other environmental impact
Improved urban climate (Reference 9)
Rooftop gardens protect homes and offices from snow, rain and heat (reference 7)
Which of the involved actors was motivated by this model?
Public actor (e.g. municipality)
Citizens / local communities
Type of innovation
Social
Policy innovation
Please specify social innovation
Hamburg is the first German city that has developed a comprehensive green roof strategy. Furthermore, the German Federal Ministry for the Environment, Nature, Building and Reactor Safety supports the strategy as a pilot project within their programme “Measures for adaptation to climate change” (Reference 2).
Novelty level of the innovation
The innovation is copied/derived from previous initiative(s) with substantial adaptation
Please specify novelty level of the innovation
The intervention is considered as a pilot project by the Federal Ministry the Environment, Nature, Building and Reactor Safety. In developing the project as an own response to climate change Hamburg took into consideration best practices and experiences of other cities (Reference 2).
Replicability/Transferability
Unknown
Please specify Replicability/Transferability
unknown
Impacts, benefits
Environmental impacts
Climate change
Lowered local temperature
Strengthened capacity to address climate hazards/natural disasters
Reduced emissions
Energy efficiency improvements
Environmental quality
Improved air quality
Improved protection against strong wind
Water management and blue areas
Increased protection against flooding
Improved stormwater management
Green space and habitat
Promotion of naturalistic styles of landscape design for urban development
Increased green space area
Increased conservation or restoration of ecosystems
Reduced biodiversity loss
Increased number of species present
Other
Description of environmental benefits
Between 2014 and 2018, the number and area of green roofs in the city grew rapidly from 80 hectares in 2014 to 138 hectares in 2018. (Reference 7) As a result of the well-subsidised project, no less than 70% of all suitable rooftops in the central area are to be topped with vegetation. (Reference 8) Rooftop gardens protect homes and offices from snow, rain and heat, and contribute strongly to energy efficiency and the reduction of emissions by delivering a natural building envelope. Local flora and fauna profit from a larger habitat and, finally, there is the option to combine green roofing with photovoltaic or solar thermal systems, which many projects within the programme have utilized. (Reference 8) And finally, the project has contributed to an improved urban climate and the reduction of biodiversity loss. (Reference 9)
- new habitats for species: "On one of the industry flat roofs a sea gull colony of >5000 individuals has found a new home, putting off other businesses to also install green roofs" (Reference 2)
Economic impacts
Reduce financial cost for urban management
Please specify other socio-cultural impact
Creating a more attractive city appearance. (Reference 8)
Description of economic benefits
For those taking part in the programme and implementing their own green walls, costs for sewers and retention reservoirs are reduced and fewer rainwater drainage fees save money. (Reference 8)
Social and cultural impacts
Social justice and cohesion
Improved liveability
Improved access to urban green space
Increased opportunities for social interaction
Health and wellbeing
Improved physical health
Gain in activities for recreation and exercise
Other
Description of social and cultural benefits
According to the municipality of Hamburg, there are plenty of results that can be attributed to the green roofs. Green facades in Hamburg contribute to the quality of life as they make the urban space more attractive. They ensure a better urban climate, create healthier living conditions and make the cityscape more beautiful. (Reference 9) Residents and employees are provided with additional green areas for sports and leisure activities. (Reference 8)
Type of reported impacts
Achieved impacts
Indicators
- increase of number of green roofs: since the beginning of the project in 2015 the total area of green roofs in Hamburg has already increased from 80 hectare to 124 hectare (Reference 2, 4)
- new habitats for species: "On one of the industry flat roofs a sea gull colony of >5000 individuals has found a new home, putting off other businesses to also install green roofs" (Reference 2)
Environmental, social and economic impacts
Climate action for adaptation, resilience and mitigation (SDG 13)
Water management (SDG 6)
Green space, habitats and biodiversity (SDG 15)
Environmental quality
Regeneration, land-use and urban development
Health and well-being (SDG 3)
Analysis of specific impact categories
Job creation: The NBS created ...
No information available
Environmental justice: The implementation of the NBS project resulted in ...
Improved access to green and/or blue spaces
Negative impacts: Did the project cause any problems or concerns?
No information was found regarding negative impacts of the project
COVID-19 pandemic
Unknown (in September 6, 2020)
Methods of impact monitoring
Process of recording NBS impacts
Collection of monitoring data continuously throughout the project to aid evaluation
Methods used to evaluate the impacts of NBS
Measurements of biophysical aspects of the NBS (e.g. temperature, water flow)
Evidence for use of assessment
Presence of an assessment, evaluation and/or monitoring process
Yes
Presence of indicators used in reporting
Yes
Presence of monitoring/evaluation reports
No evidence in public records
Availability of a web-based monitoring tool
No evidence in public records
Impact assessment mechanism
Name of any specific impact assessment tools
HafenCity university is providing scientific support to the Green Roof Strategy for evaluation. Scientists at the university are collecting data on water retention and the water management effectiveness of green roofs especially with severe cloudbursts. (Reference 2)
Link to the output of assessments
https://ec.europa.eu/environment/europeangreencapital/wp-content/uploads/2011/0…
Use of GIS in mapping impacts
No evidence in public records
Citizen involvement
Citizens involvement in assessment/evaluation
Unknown
Citizens involvement in the analysis of the assessment/evaluation
Unknown
Follow-up to the evaluation / assessment
Unknown
References
Web links relevant to the intervention
Reference 1: The official website of the program
Refernce 2: The description of the project on the website of Climate-Adapt
Reference 3: Green Roof Strategy for Hamburg
Reference 4: Green roof price
Reference 5: Green Capital
Reference 6: Hamburg, Green Capital, 5 years on
List of references
1. Hamburg.de. (2017). Hamburger Gründachförderung: "Auf die Dächer - fertig - grün!". [online] Available at: http://www.hamburg.de/gruendach [Accessed: 1 Sept. 2020].
2. Climate.adapt.eeea.europa.eu. (2016). Four pillars to Hamburg’s Green Roof Strategy: financial incentive, dialogue, regulation and science. [online] Available at: http://climate-adapt.eea.europa.eu/metadata/case-studies/four-pillars-to-hamburg2019s-green-roof-strategy-financial-incentive-dialogue-regulation-and-science/#legal_aspects [Accessed: 1 Sept. 2020].
3. Bornholdt, H. (2016). Green Roof Strategy for Hamburg, Hamburg: Behörde für Umwelt und Energie. Available at: https://www.bfn.de/fileadmin/BfN/klimawandel/Dokumente/ECBCC2015/2015-11-18/Session4/Bornholdt_-_Green_roof_strategy_Hamburg.pdf [Accessed: 1 Sept. 2020]
4. Behörde für Umwelt und Energie (2017). Dokumentation: Hamburger Preis für grüne Bauten. Hamburg: Behörde von Umwelt und Energie. [online] Available at: https://www.hamburg.de/hamburger-preis-fuer-gruene-bauten/9190570/hamburger-preis-fuer-gruene-bauten/ [Accessed: 01 Sept. 2020]
5. ec.europe.eu. (2017). European Green Capital. [online] Available at: http://ec.europa.eu/environment/europeangreencapital/index_en.htm. [Accessed: 01 Sept. 2020].
6. Ministry of Environment and Energy. (2016). Hamburg – European Green Capital: 5 Years On: The city takes further. Hamburg: Ministry of Environment and Energy. Available at: https://ec.europa.eu/environment/europeangreencapital/wp-content/uploads/2011/04/Hamburg-EGC-5-Years-On_web.pdf [Accessed: 1 Sept. 2020]
7. Köhnlein, B. (2019). Green Roof Strategy Hamburg. Hamburg: Behörde für Umwelt und Energie. Available at: https://ec.europa.eu/info/sites/info/files/6.2_green_roofs_hamburg_kohnlein.pdf [Accessed: 1 Sept. 2020]
8. Hamburg.com. (nd.) Green Hamburg: Green Roofs. [online] Available at: https://www.hamburg.com/residents/green/11836394/green-roofs/ [Accessed: 1 Sept. 2020]
9. Behörde für Umwelt und Energie. (nd.) "An die Wande - Fertig - Grün!". Hamburg: Behörde für Umwelt und Energie. Available at: https://www.hamburg.de/contentblob/13871400/094cf33ea1fa2fb603901be28f742038/data/d-fassadenguide.pdf [Accessed: 1 Sept. 2020]
Comments and notes
Comments
2020 comments:
The strategy was evaluated by a working group, but I can't find any details about it. "Within the city a stakeholder group was established including housing estate companies, constructors, landscape architects and urban planners. Parallel to the dialogue with other cities this group was involved in defining the incentive programme. The group has remained active since and during its bi-annual meetings the Green Roof Strategy is evaluated by the working group." (Reference 2)
Public Images
Green roofs aerial photo
Green roofs aerial photo
Green Bunker
Green Bunker