Oslo, Norway
City population: 591933
Duration: unknown – 2015
Implementation status: Completed
Scale: Sub-microscale: Street scale (including buildings)
Project area: 7 m2
Type of area: Central Business District / City Centre
Last updated: October 2021

The Urban Ecology Agency of Oslo (Bymiljøetaten) installed two CityTrees in the city of Oslo to act as green lungs in the city and reduce air pollution. The two CityTrees were placed at the Solli plass by Sommerrogata and on Nordraaks plass, close to Slottsparken. The CityTree is an environmentally-friendly plant wall with benches. (Ref. 2) It is an invention of a German company, Green City Solutions, and acts both as an aesthetically attractive furniture for resting, while simultaneously combating air pollution in city centres. (Ref. 1)

CityTree Project
Monica Thorud Olsen, retrieved 08/24/2018


Nature-based solution

  • Nature on buildings
  • Green walls or facades
  • Other

Key challenges

  • Climate action for adaptation, resilience and mitigation (SDG 13)
  • Climate change mitigation
  • Green space, habitats and biodiversity (SDG 15)
  • Green space creation and/or management
  • Environmental quality
  • Air quality improvement
  • Noise reduction


Creation of new green areas

Project objectives

This NBS aimed to achieve the following: Reduce air pollution, air temperature and noise using mosses; Self-sufficient energy and watering system; Environmentally friendly construction; Increase in biodiversity and green space in cities (Ref. 1)

Implementation activities

-Mosses, suitable for the local climate, were planted on a vertical wall (Ref 2, 3). -The construction contained sensors collecting environmental and climatic data, to regulate and control the unit and ensure that the plants survive. The CityTree combines mosses with IoT technology, enabling measuring, analysing and controlling the environmental benefits of the wall in real time. (Ref 2, 3). -The plant wall also contained various plants that attract insects that contribute to the biological diversity in the city (Ref. 2)

Climate-focused activities

Climate change mitigation:

  • Increase green urban nature for carbon storage (wetlands, tree cover)

Main beneficiaries

  • Local government/Municipality
  • Private sector/Corporate/Company
  • Citizens or community groups


Management set-up

  • Government-led

Type of initiating organisation

  • Local government/municipality

Participatory approaches/ community involvement

  • Consultation (e.g. workshop, surveys)

Details on the roles of the organisations involved in the project

Local Government: Oslo Municipality (Bymiljøetaten) - Installment of City Trees (Ref. 5) Private Sector: Green City Solutions - Provider of the product. (Ref. 1). Citizens: The Urban Ecology Agency posted the news of their instalment of the two CityTrees on their Facebook page and engaged with citizens commenting on the new features in Oslo's cityscape (Ref. 5)

Project implemented in response to ...

... an EU policy or strategy? Unknown
... a national policy or strategy? Unknown
... a local policy or strategy? Unknown (Unknown)


Total cost

€50,000 - €100,000

Source(s) of funding

  • Public local authority budget

Type of funding

  • Unknown

Non-financial contribution


Impacts and Monitoring

Environmental impacts

  • Climate, energy and emissions
  • Lowered local temperature
  • Enhanced carbon sequestration
  • Environmental quality
  • Improved air quality
  • Reduced noise exposure
  • Green space and habitat
  • Increased green space area

Economic impacts

  • Unknown

Socio-cultural impacts

  • Health and wellbeing
  • Gain in activities for recreation and exercise

Type of reported impacts

Expected impacts, Achieved impacts

Presence of formal monitoring system


Presence of indicators used in reporting


Presence of monitoring/ evaluation reports

No evidence in public records

Availability of a web-based monitoring tool

No evidence in public records


CityTree (2015)
Monica Thorud Olsen, retrieved 08/24/2018
CityTree (2015)
Monica Thorud Olsen, retrieved 08/24/2018
Source: Ref. 2, Svanhild Blakstad