Biolit Vertical Green: The wall as an air freshener

Cities are growing all over the world: The UNO predicts that the percentage of the population living in cities will rise to over 60 per cent by 2030 – a development which, in combination with climate change, entails considerable challenges in urban areas. In order to reduce the formation of heat islands and improve the air quality in cities, the Fraunhofer Institute UMSICHT and its partners are researching and testing a new kind of solution for turning walls into green spaces. For the first time, they have taken a new approach in this respect and used sandy limestone, a cost-effective, absorbent and fluid-retaining building material.

As a consequence of climate change, researchers expect more severe heat waves and increased heavy rainfall. This is a problem, especially in urban areas where the rainwater cannot seep away due to the dense nature of construction. Any rainwater flows practically unhindered into the sewage system. In the case of very heavy rainfall, this means that the waste water systems reach their limits.

There is a further problem: the lack of plants reduces the natural capacity for evaporation, buildings and road surfaces store up the sunshine and the high number of buildings prevents the natural supply of air from the outlying districts reaching the inner city. This leads to the formation of localised heat islands, where the temperature is often above that of the surrounding area.

Engine for progress:

  • Improvement of the microclimate
  • Improvement of rainwater retention
  • Air purification
  • Effective adaptation measure for sealed areas
  • Innovative irrigation concept

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Photo: Fraunhofer UMSICHT

Herb wall at the state horticultural show in Würzburg

The way out: turning walls into green spaces

The Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT, in collaboration with Dipl.-Ing. Berthold Adler and Ruhrbaustoffwerke GmbH & Co. KG., which belongs to the UNIKA Group, has been researching and testing a solution for this problem. The system, which has been patented by Fraunhofer UMSICHT and Berthold Adler, is based on a building element that can be planted with vegetation and used to build up large walls in a modular way. With regard to its material structure, which is based on sandy limestone, the building element was specially developed for its capacity to store and transport water. The advantage of the system is that Biolit Vertical Green can simply be mass-produced since the established production processes for sandy limestone can be used. The walls can be planted at will on several levels. The sandy limestone absorbs water particularly quickly and releases it again just as rapidly. This allows the absorbent and fluid-retaining building material to be used directly as part of the watering system: the limestone is watered by means of an integrated system and releases the water to the plant substrate, meaning that the plants can be watered in an ideal way.

Sandy limestone and moss are a good combination

As a result of the plants in the walls, CO2 is absorbed and oxygen production is stimulated. The sandy limestone creates especially good growing conditions for mosses: they can flourish here and are said to be potentially able to filter particulate matter from the air. Especially in densely-built neighbourhoods in cities, the system can help to counteract the threat of heat stress, to improve the microclimate and air quality and to increase the retention of rainwater in the case of very heavy rainfall. Surfaces that are planted also provide good insulation and can therefore also offer energy-saving potential. The project is thus simultaneously developing possible solutions for various aspects of climate protection and adaptation to the impacts of climate change.

Fraunhofer UMSICHT

Foto: Fraunhofer UMSICHT

Biolit Vertical Green® is a new system for planting vegetation vertically, based for the first time on mineral substrates. The system can be used for a variety of purposes – as a separating wall, as wall covering, as a vertical garden and, in the future, perhaps as a planted noise barrier on streets and railways.

Dr Holger Wack, Deputy Head of Material Systems and High Pressure Technology, Group Leader Construction at Fraunhofer UMSICHT

Partners and sponsors

  • Dipl.-Ing. Berthold Adler
  • UNIKA Ruhrbaustoffwerke GmbH & Co. KG
  • Weckelmann Bautenschutz
  • Fraunhofer-Institut für Umwelt-, Sicherheits- und Energietechnik UMSICHT