The solution to quantifiably
improve city air
This is how it looks

Proof of performance from independent experts

Since its invention in 2014, the CityTree is continuously being further developed. This includes all parts of this worldwide unique product idea: from design to energy and water supply to environmental performance. Thereby, we don’t just build on our comprehensive background experience but also on the expertise from different research-, technology-, sponsor- and certification partners. A particular development focus is on the steady improvement of the City Tree’s environmental performance that is being verified and reviewed by independent experts in complex laboratory and field studies.


European Union Brussels

Expertise :
“Horizon 2020” is an investment instrument, an excellent flagship initiative that supports EU competitiveness at an international level through innovation

Cooperation :
Financing of development projects from Europe with a technological approach and high innovati on potenti al, here the measuring of air fi ltering performance

Climate KIC Berlin

Expertise :
Europe’s largest public-private network for innovations to prevent climate change, consisting of companies, institutes and the public sector

Cooperation :
Financial support for CityTree tests and certification projects in urban environments as part of a Europe-wide funding project („Scaler Project“)

ODINE Brussels

Expertise :
Leading European open data incubator for supporting new digital business models of mainly younger companies

Cooperation :

Financial support in the development of a software application (AirCare) for visualising air quality data

Research laboratory & field

Fiatec Mainleus

Expertise :
Laboratory specialising in air filter inspections and the development of international inspection standards for air filtering

Cooperation :
Execution and analysis of comprehensive measurements with regard to the particulate matter filter performance of various types of moss

Institute of Air Handling and Refrigeration Dresden

Expertise :
Expert contact for research and development questions in the fields of air handling and refrigeration and their areas of application

Cooperation :
Execution, analysis and documentation of laboratory tests to measure the filter capacity of mosses with regard to nitrogen oxides

TROPOS Leipzig

Expertise :
Leading insti tute for interdisciplinary and applicati on-
oriented basic research into the relati onships between health and climate

Cooperation :
Execution, analysis and documentation of measurements of the particulate matter filter performance of the CityTree under real test conditions

Karlsruher Institut of Technology Karlsruhe

Expertise :
Internati onally leading scienti fi c insti tuti on for basic research in the context of society and environment

Cooperation :
Development, execution and analysis of test procedures for measuring the CityTree’s take-up of nitrogen dioxide in a real-life environment

ISAC-CNR Bologna

Expertise :
The Institute of Atmospheric Sciences and Climate aims at an integrated scientific understanding of the atmosphere, the ocean and their processes

Cooperation :
Measurement on the effectiveness of the CityTree in an urban street canyon in Modena, Italy

Measurements & simulations

Grimm Aerosol Technic GmbH Ainring

Expertise :
World leader in the development and manufacture of high-precision optical particulate matter measuring devices including cutting-edge software applications

Cooperation :
Delivery and implementation of high-tech measuring devices for the precise measurement of the particulate matter filtering performance of mosses


Expertise :
Developer of software to simulate micro-climates and measure the effects of sustainable measures based on objective scientific methods

Cooperation :
Simulations to determine the most effective locations for CityTrees and their potential effect on the environment in the immediate surrounding area


TÜV Nord Hannover

Expertise :
Evaluates, inspects and certifies in safety matters in private and commercial areas, which leads to the awarding of an internationally highly regarded test seal

Cooperation :
Creates evaluations and plans certification for testing under laboratory conditions and in the real urban environment

Results from Research & Development

The process of permanent optimization of the product concept is based on a simple principle: at the beginning is the development of a prototype that is going to be produced on a small scale considering previously taken laboratory tests. In real urban living environments, the environmental performance is finally being tested, before a validation within the scope of a broader designed test scenario with several CityTrees is being conducted. The newly available product generation of the CityTree provides a better environmental performance. New performance data is always verified and gradually published in close collaboration with external research-, technology-, sponsor- and certification partners.

Particulate Matter

Average observed filtration efficiencies are 19±7%, 15±5% and 11±5% for PM10, PM2.5 and PM1, respectively.

(ISAC-CNR, Bologna, Italien, November 2017)

Particulate Matter

Despite some fluctuations, the mean value from the time series was 0.77 therefore, resulting in a reduction of the mass fraction after active filtering by the CityTree of 23%.

(Tropos, Leipzig, September 2017)

Particulate Matter

… at a constant
air flow of 5.5 m3/min, aerodynamic related efficiencies varied according to the moss species and ranged from 20%-53%, 26%-64% and 56%-86% for PM1, PM2.5 and PM10 respectively.

(Fiatec, Mainleus, April 2017)


Finally, results indicated that deposition of NOx were very different for the investigated materials with values ranging from 0 to 8%.

(ILK, Dresden, März 2018)

Cloud based communication between CityTree and AirCare

Before setting up several CityTrees – e.g. in a street canyon – an extensive location analysis is ideally being conducted. The networking of the CityTrees is ensured by the modern sensor technology in each CityTree and the permanent data transfer via the cloud to a proprietary software application (AirCare). It displays data about the environmental performance as well as the condition of each CityTree and also provides essential information for optimal maintenance and care.






Location analysis

Extremely complex and data-driven simulations, using the ENVI_MET® software, determine the best locations for the optimal impact of CityTrees in a customer-defined urban habitat (for example, in a heavily polluted street).


The installation (positioning, alignment & commissioning) is ideally based on results from the site analysis. The built-in sensors permanently transmit data to the cloud, providing information about both the condition and the environmental performance of CityTrees.


A specially developed dashboard visualizes the data accumulated in the cloud in real time and thus provides information on the condition monitoring and environmental performance of each individual CityTree – over individually defined periods or for comparison with objectives set by the customer.

Care & maintenance

The data generated by the sensor technology on the condition of each CityTree are made available to service teams via a maintenance app, thus ensuring an appropriate care (plant) and maintenance service (technology) that guarantees functionality and longevity.

Location analysis – for an optimum effect

Urban living spaces are increasingly exposed to environmental pollution. Motivated by the desire to make a valuable contribution to sustainably favourable living conditions in cites, the company ENVI_MET has developed particularly advanced simulation techniques. Based on microclimate models, the software rests on a foundation of scientifically-recognised methods and the approach of viewing the environment as a holistic organism. With the help of the software, sustainably effective measures to reduce environmental pollution can be visualised quantitatively with regard to their impact, and then evaluated.

3D modelling

One of the world’s leading software applications for microclimate simulations from ENV_MET® saves data from various sources on the local climatic, structural and geometrical conditions in preparation for the next step (complex simulation calculations).


In addition, local environmental factors such as the meteorological situation and the degree of air pollution are used as a basis for lengthy simulation calculations, so that their meaning with regard to the future impact of the CityTree can be visualised.

Result analysis

The huge amounts of data are processed in order to determine the optimum location for each individual CityTree – with the results also being presented visually – as well as to calculate its caculated effect on the reduction of air pollution in the section of urban living space being studied (for example a street).


Finally, the results of these micro- climate simulations are summarised in a report and presented together with corresponding recommendations. In this way, subsequent decisions regarding the implementati on of CityTrees in a particular urban living space are based on a solid foundation of information.

The world’s first bio-tech filter to quantifiably improve air quality

Mosses for cleaner air

Different types of moss bind environmental toxins such as particulate matter and nitrogen oxides while producing oxygen at the same time.

Cutting edge IoT technology

Integrated IoT technology delivers comprehensive information on performance and status as well as environmental data on the CityTree’s surroundings.

Variable ventilation

Controllable ventilation technology allows airflow to be intensified, meaning that the filter effect can be increased as required.

Optimum watering

Water provision is either connected or independent, thanks to a fully automated irrigation system.

Energy provision

Energy is provided via grid connection.

Pleasant cooling effect

Mosses store large quantities of moisture, and the considerably increased evaporation surface creates an immense cooling effect.

CleanAir+ – for more cleaner air

By activating the ventilation system already in place in the construction, airflow can be increased. The CityTree therefore becomes independent of the natural wind flow that can be very different from location to location. The amount of air flowing through can be controlled individually, to suit the respective air pollution situation or also within predefined periods of time during a day. The CityTree’s air filter performance is considerably increased – as is, therefore, the positive effect on the environment in the form of a larger amount of cleaner air.

AirCare – for proven environmental performance

The CityTree contains a unique IoT technology infrastructure that includes numerous points of measurement. The integrated sensors generate huge amounts of data in real time, which can be viewed using a specially developed dashboard. The data provides comprehensive information about the environmental performance and the status of the CityTree. Information on the environmental situation is also available. Therefore, the environmental performance of an individual – or of several – CityTrees can be quantitatively demonstrated at any time. In addition, optimum maintenance and care are guaranteed, which ensures that the CityTree remains functional and has a long life.