Green roof strategy - Basel

The "Green Roof Strategy" (2005-2007) is an initiative of the city of Basel in Switzerland with the main aim to increase the coverage of green roofs in Basel through the use of a combination of financial incentives and building regulations. The instrument is the successor of an earlier initiative that provided subsidies for the installation of green roofs between 1996 and 1997. As a nature-based solution, the green roofs promoted by this policy instrument offer multi-functional benefits for e.g. climate change mitigation (reduced energy consumption of buildings) and adaptation (lower temperatures, reduced surface runoff, etc.), as well as for the protection of biodiversity. The Strategy was supported by an awareness-raising campaign to promote the acceptance of the measures.

Overview

Type of instrument:

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

Challenges addressed

Water management (e.g. reuse)
Green space management (e.g. accessibility)
Heat stress and heat island effect
Human health, comfort and well-being

Consideration of nature-based solutions:

In densely built-up areas where it is impossible to create extensive parks and plant trees, green roofs are a viable greening option. With its green roof strategy, the city of Basel supported the mitigation of the urban heat island effect by lowering temperatures (which also reduces the need for cooling) and achieving better insulation of buildings, thus resulting in more energy-efficient buildings as well as carbon sequestration and storage through the plants. Additional benefits include improved stormwater absorption and delayed runoff (reducing the risk of flooding during heavy rain events), improved air quality, and potentially biodiversity protection.

Targeted (peri-)urban areas:

External building greens

Good practice characteristics:

Effective

Support multifunctional NBS

Locally appropriate

Potential to be replicated / upscaled

Governance

Government body/bodies

Initiating body:

National Department of Environment and Energy; City of Basel

Instrument design:

Details about how the instrument was designed:

While the city of Basel provided the political framework for the green roof strategy and accompanied it with an awareness campaign, the Department of Environment and Energy was responsible for implementing the financing of this instrument, as the levy was collected from citizens through their energy bills. Prior to the first incentive programme (1996-1997), the Department of Environment and Energy conducted a poll with the Swiss public to determine the level of support for an electricity tax to pay for energy-saving measures. The focus on green roofs was promoted by researchers from the Zurich University of Applied Sciences in Wädenswil (Switzerland), who aimed to influence decision-makers in Basel to amend the building regulations and offer financial incentives to increase green roof coverage. Various stakeholders were consulted when developing the green roof strategy, and in establishing the first incentive programme: the local business association, the horticultural association, the green roof association, the Pro Natura Basel environmental organization, the Department of Parks and Cemeteries in the City of Basel, and the National Department of Environment, Forest and Landscapes.

Involvement of non-governmental actors:

Private sector, corporate, business

Researchers, university

Citizens or community groups / NGOs

Type of actor involvement:

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

Expert task force consultation

Instrument implementation:

Type of involvement:

The city of Basel incentivised green roofs in Basel through a combination of financial incentives and building regulations. The incentive programmes were targeted at businesses as well as the residents of Basel. While the incentive programme does not cover public buildings, the laws enacted for the mandatory greening of new and renovated flat roofs apply to all buildings in Basel.

Type of non-governmental actors involved:

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

Targeted actors:

Researchers, university

Financing

Sources of funding:

Public regional budget

Budget:

Unknown

Details about instrument financing:

The programmes were funded from the Energy Saving Fund made up of 5% of all customers’ energy bills in the Basel canton. The City of Basel has promoted green roofs via investment in incentive programmes, which provided subsidies for green roof installation (1996-1997 up to 20 CHF per m2, then 2005-2007 up to 30-40 CHF per m2, in the latter case only for retrofitting existing buildings).

Monitoring, evaluation and impacts

Is a monitoring framework in place?:

Did an evaluation take place?:

Achieved outcomes and impacts:

A comprehensive suite of mechanisms, from incentives to statutory regulations, has ensured a wide uptake of green roofs in Basel and laid the foundation for the second funding round to support the strategy. Outcomes of the renewed green roof strategy (2005-2007) include the delivery of climate change mitigation benefits (e.g. reduced emissions and carbon sequestration) and adaptation benefits (reduced temperatures), improved risk management and resilience, enhanced physical and mental well-being (e.g. provision of health services, a more natural urban environment), and increased awareness of green roofs and their effectiveness and potential co-benefits. With 5.71 m2/inhabitant in 2019, the city of Basel in Switzerland has the largest area of green roofs per capita in the world. For developers, installing green roofs is now considered routine and they make no objections to installing them.

Success factors and lessons learned:

While the original motivation was to save energy, the focus of the strategy shifted over time to concentrate on biodiversity and then to the role of green roofs in adapting Basel to climate change. The strategy also serves as a good example of seeking out and utilising opportunities for climate change adaptation and biodiversity conservation that are provided by existing/ongoing urban and infrastructure developments that are driven by other goals. Green roofs are an excellent example. Championship of the project by the Zurich University of Applied Sciences also contributed to the initiative’s success. The involvement of all stakeholders from the beginning of the initiative helped to address questions and concerns and ensured that everyone’s goals were met. During the incentives programme in 1996-97, the media interest was high, and newspapers and posters were used to inform residents of Basel about the subsidies. This played an important role in its success because it increased awareness of green roofs across a range of stakeholder. A number of technical lessons emerged from the implementation of the strategy, relating to the growing medium and ecological requirements of green roofs to maximise their benefits.

Sources and further information

Further documents

Weblinks:

https://climate-adapt.eea.europa.eu/metadata/case-studies/green-roofs-in-basel-s…

https://oppla.eu/casestudy/18381

Photos

@Michael Zogg