Complete Facade Greening: High-Rise Apartment Building in Milan

Flora and fauna take on added importance in this exemplary living concept for increasingly densely populated metropolises by becoming an integral part of the building's shell.

Architect: Boeri Studio
Location: Milan, Italy

The shells of the two high-rise apartment buildings at Porta Nuova are not merely home to plants. Thanks to the 730 trees, 5,000 bushes and 11,000 ground covers planted on the large balconies, the towers have created space for a 'vertical forest', which has more than a unique appearance; it enables many other positive features as well. On the one hand, the green façade provides protection from the sun in the summertime and improves the microclimate for a better living atmosphere. On the other hand, the architects consider this project as a good example of 'increased density and anti-urban-sprawl measures' for the cities of the future, which will be more densely built than they are today.

Rendering of the high-rise apartment buildings, 112 m and 80 m 

In terms of both economy and ecology, the idea of not using valuable urban space for small-scale development, but rather offering enhanced quality of life even in stacked apartments, has been around since the beginning of the Modern era. However, what is new is the attempt to give this desire a clearly structured, aesthetic and – literally – natural face. Stefano Boeri describes the high-rises as 'biological architecture that derives from technically and mechanically based aspects of ecological sustainability'. For him, sustainability means not only preserving resources, but also the possibility to bring organic life into the building.

Geothermal energy 

Diagram of the protective 

function of the façade greenery 

Selection and anchoring of the plants 
Densely built urban spaces

Unlike in more conventional construction methods, the forest that was to be integrated into the building shell proved relatively complex. For example, the characteristics of all 40 of the tree types used here were precisely analyzed and even tested in a wind tunnel in order to determine the most suitable species for the requirements of height, wind strength and sunlight at every level of the building. The olive and pomegranate trees were anchored in the substrate layer of the concrete boxes with stable rigging belts. An automatic hose-watering system gives the plants the correct amount of water according to the season, direction, storey and species, while specially introduced insects keep vermin at bay.

Construction works in summer 2013 with façade greenery

All the garden work here is carried out by a gardening company- the associated costs will go largely unnoticed by the inhabitants of this building, which is categorized as luxury real estate. It remains to be seen whether Boeri's high-rises, which will be ready for occupation in 2014, will prove to be an affordable model for the future, and whether it will be possible to keep the promises made by these impressive renderings.