Facade Greening on High-Rise Buildings
High sealing rates due to inner-city densification are increasingly having a negative effect on the microclimate in large German cities. The consequences are a deterioration in air quality due to increased emissions and a lack of green spaces, as well as sometimes extreme inner-city temperatures. In so-called urban heat islands, it can be up to 10 degrees warmer in summer than in the surrounding countryside. To counteract this development, various urban planning measures are currently being developed and applied. One of these is the greening of building roofs and, more recently, building facades. Greening of facades is particularly suitable for high-rise buildings, as they have a lot of vertical space. Green roofs and facades clean the air in the course of fine dust absorption, the evaporation of the plants causes a cooling of the temperature, traffic noise can be dampened and the general quality of stay increases. However, greening buildings poses a number of challenges: installation is complex and cost-intensive, and the plants require a complex irrigation system with modern building technology. Fire protection, in particular, is complicated. It is important which plant species are used and in which condition they are. The fire behavior of the greenery also depends on its wood content, growth form, leaf mass and attachment material.
It is still unclear what effect green facades have on biodiversity. Frankfurt architect Christoph Mäckler is critical of the trend and calls for more trees to be planted on the ground. Politicians oppose this and want to “turn the Frankfurt Skyline into a green silhouette.” Accordingly, there are to be mandatory specifications for greening high-rise facades in the next high-rise master plan.
Greening at the EDEN Tower in Frankfurt am Main
The EDEN Tower, which is currently under construction, is the first high-rise building in Frankfurt with a green facade. Designed as a lighthouse project, it is intended to set an example in terms of sustainable residential construction and to highlight possible new perspectives. 20 percent of the facade is greened, which corresponds to an area of 2,000 square meters. This involves 15 different plant species that were carefully selected, particularly in terms of fire protection, and would merely smolder in the event of a fire.
Around the high-rise building, 10 columns are installed from which green, fire-resistant mats weighing 40 kilograms hang. These are filled with a layer of mineral wool, on which the plants then take root. A drip system via hoses installed in the facade takes care of irrigation as well as supplying nutrient-rich fertilizer. There are sensors in the mats that measure humidity and thus efficiently regulate the water and substrate balance. Twice a year, the plants are to be pruned, with gardeners rappelling down the facades from a gondola mounted on the roof. The approximately 195,000 plants are expected to last up to 8 years, after which they will need to be replaced. In addition to the climatic benefits of the greenery, the plants also create a feel-good effect for the building’s residents as a separating element between the balconies. The roof terrace also follows the character of the high-rise building and is designed with lush greenery.
“The EDEN has taken on a pioneering role for the development of green facades in Frankfurt. It is all the more pleasing to see now that there are to be mandatory specifications for the greening of high-rise facades and hopefully many more buildings like the EDEN will follow. With the EDEN, 195,000 plants will contribute to an improved urban climate and ensure well-being for future residents. It gives us great pleasure to accompany this innovative project as it grows.”
Helen Lindner (Head of Residential Development Germany at the Real Estate Firm JLL)
The 98-meter-high residential tower has 27 floors, offering space for practical 1-room apartments through to spacious 5-room apartments. Originally started as a project by gsp Städtebau, construction of the EDEN Tower has been continued by Belgian real estate developer Immobel since 2019. Completion is scheduled for 2022.
The watering substrate
the plant mats
The roof terrace under construction
The SKYLINE ATLAS with Cengiz Aba from CMT Baumanagement
Vertical plant mats on the facade of the EDEN Tower