Green roofing

Living roof

Mega-cities are developing at a rapid pace and are transforming the cityscape. Concrete and glass are displacing green areas and rural surroundings. Innovative ideas for environmental protection and sustainability are urgently required. In this context, plants on roofs and facades can achieve amazing things. Nonwovens from Freudenberg Performance Materials ensure that buildings and flora remain protected.

Cities promise a better quality of life, more attractive jobs and a broader cultural and educational offer. For these reasons, more and more people worldwide are taking advantage of the opportunities on offer in cities. According to the United Nations, more than half of the world’s population is already living in an urban environment. By 2050, that proportion is expected to have risen to 70 percent. So-called mega-cities are already being built and are now home to millions of people – especially in Asia.

Current residents: Tokyo: 38 million, New Delhi: 25 million, Shanghai: 23 million

By way of comparison: New York: 8.5 million, Berlin: 3.5 million, Paris: 2.2 million, Milan: 1.3 million

However, more and more green space is being lost as a result of urban development. As mega-cities in particular struggle against increasing pollution, green spaces are urgently needed to ensure good air quality. In addition, there are problems such as particulate matter and overheating. Urban planners are desperately looking for solutions to make urban development more environmentally balanced.

Plants as air purifiers

Plants absorb carbon dioxide and release oxygen, thus boosting the oxygen content of the air. But that is not all. Plants remove toxins, clean the air of chemicals and thus contribute significantly to improved air quality. More and more city planners and architects are therefore increasingly thinking about integrating larger quantities of plants into roofs and facades to arrest air pollution.

“With so-called ‘green roofs’, we can significantly improve air quality. In addition, with the right subsoil, the plants contribute to the improvement of thermal and acoustic insulation.”

Cristina Deponti, architect, Milan, Italy.
Green roofing

Competition design by Cristina Deponti for a comprehensive roof greening concept in Milan.

Cristina Deponti works as an architect in Milan and has already worked on some projects of this nature. Among other things, she took part in a contest with a proposal for a gardening concept for Milan’s roofs. But it doesn’t stop with the greening of roofs. Greening entire facades is a hot trend that is becoming more and more popular.

With the ‘Bosco Verticale’ (vertical forest), the 110- and 80-meter-high planted twin towers, Deponti has had the world’s most famous example of facade greening in daily view since 2014.

Bosco Verticale

Bosco Verticale in the center of Milan, Italy

The 900 trees and 2,000 plants of the Bosco Verticale in Milan, along with its terraces and balconies, together make up a forest area of around 7,000 square meters, roughly the size of a football field.

To allow the greening to actually function, the building needs to be protected from moisture while at the same time ensuring that the plants are supplied with essential nutrients. When combined with a suitable subsoil, sound and building insulation can also be improved.

“Special materials used as the subsoil for the greening can save a considerable amount of energy. The residents of the building are then protected from the cold in winter and the heat in summer. In addition, noise is less intrusive.”

Cristina Deponti, architect, Milan, Italy.
Green roofing

The right subsoil

Waterproof bitumen membranes ensure that moisture, substrate and roots stay safely where they belong, outside the building. Freudenberg Performance Materials supplies the ideal high-performance nonwoven for this purpose. The glass-fiber-reinforced polyester nonwoven is made from recycled PET bottles and serves as a carrier material for bituminous membranes. This forms the basis for permanent roof greening and is followed by layers of insulating material as well as drains and the nutrient substrate.

Roofing Construction

PET bottles are recycled at Freudenberg Performance Materials. It is a key raw material to manufacture a nonwoven used as carrier materials for bituminous waterproofing membranes or as thermal and acoustic insulation.

Greening improves wellbeing

“Being able to see something green out of the window has been proven to have a beneficial effect on us”, observed Prof. Dr. Riklef Rambow from the Department of Architecture Communication at the Karlsruhe Institute of Technology. Rambow is intensively involved in architecture psychology and the interaction between people, buildings and plants. For example, a green environment can to a certain extent aid the recovery of sick people, as indicated in a study conducted by Texan Professor of Architecture Roger Ulrich in 1984. Ulrich showed that a group of patients who were allowed to look at trees shortly after an operation recovered faster than a comparable group, whose gaze was restricted to the walls of buildings. The study marked the beginning of a series of similar investigations with the same result.

The microclimate of a building also benefits from a ‘green envelope’. In the summer, the planted areas and patios protect against excessive warming and replace the air-conditioning system with natural water evaporation. They also improve air quality, protect against noise and provide additional insulation in winter. What’s more, the environmentally friendly cultivation of fruit and vegetables on one’s own roof could become even more important in the future, due to the reduction in cultivable land.

“Young architects are much more open-minded and willing to experiment in their ideas and designs for innovative and sustainable urban greening than the older generation”, Rambow added. “So we can look forward to future plans and possible positive developments in large cities.”

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