Sponge City

smart service | august 2021

healthy urban trees


Sponge City for Urban Trees is a concept that – using local materials – seeks to ensure a subsoil structure in streets that is conducive to the growth of healthy trees. Trees are not only fundamental to the city’s blue-green infrastructure but are also key to addressing climate change.

The Sponge City for Urban Trees aims to mitigate the climate impact in cities through a blue-green infrastructure based on the healthy growth of urban trees that are the best instrument to cool down the street and foster urban life.

The project aims to implement the Sponge City concept in several Austrian cities by planting trees in streets and squares with a substrate that offers the trees about 30% of cavities where their roots can expand and where the water necessary for their consumption is retained.

Status & Application:
The Sponge City for Urban Trees concept has been applied in different cities in Austria.


Characterization along 5 societal goals: Happiness, Safety, Innovation, Profitability, and Circularity.

The graph below shows for which of these themes the product is mainly relevant on a societal level. Some products are more specialized, while others may be covering all topics equally. The results are based on a self-evaluation questionnaire that was developed by URBAN MENUS and filled in by the products or services themselves.

Below is an explanation of how the product or service may contribute to the 5 themes, based on the information provided by the solutions in the onboarding process as well as research by the URBAN MENUS team.

For more details about the analysis and the 5 main themes, please click here.


Healthy urban trees and an overall greener environment can improve the quality of life and health in cities, therefore contributing to happiness – for instance by creating a more pleasant climate, an improvement of overall appearance and by creating outdoor spaces where people like to spend time together as a community.


Well-tended, healthy greenery can improve the overall impression of a neighbourhood as well as increase the social climate, thus potentially leading to an increased sense of safety in a community.


Even though trees are an integral part of most cities, giving them the root space they need is not commonly practiced yet. The Sponge city approach is innovative in this sense and carries several benefits.


Greenery such as urban trees can lead to cooling effects and improve the microclimate in a city, therefore relieving the healthcare system. Furthermore, with the Schwammstadt principle, the lifespan of urban trees is increased, reducing overall costs. Also, it can be an impulse for the emergence of Urban Forestry.


Sponge city provides natural air conditioning of the city. It allows the creation of shady, cooling, zones in the city by using trees as infrastructure to create climate-resilient areas without losing the multifunctionality of living urban spaces, using only natural building materials. Furthermore, excess rainwater from heavy rain events can be retained and the groundwater under the city can be replenished.