The evolution of green roofs
Since the beginning of the modern era, many countries on several continents have kept the idea of the green roof alive. This concept has been widely adopted in different regions and cultures. In the mid-1880s, new technology introduced the idea of a living roof on top of a concrete roof. The first model of this roof appeared at the 1867 World’s Fair in Paris. The model illustrated a green roof with a waterproofing and drainage system and is considered the first modern design of an extensive green roof.
In the 20th century, the creators of modern architecture Le Corbusier, Alvar Aalto, and Frank Lloyd Wright began to apply the green roof and walls in their designs to unite the natural with the built. Their famous designs are a clear sign of this concept Villa Shodhan, Villa Mairea, and Millard House). The following photos represent famous buildings designed with green roofs between the 1920s and 1960s:
The Rockefeller Center rooftop green gardens in New York, considered the first modern green roofs in the United States (1930)
The House Over the Falls (Fallingwater), also known as the Kaufmann Residence, is a suburban house built in 1936-1939 by American architect Frank Lloyd Wright in southwestern Pennsylvania. It was built in a picturesque area called Bear Creek.
The name of the house is explained by the fact that it was built on a small waterfall. Soon after its completion, it gained a reputation as a benchmark for organic architecture. In 1966, it received the status of a United States National Historic Landmark.
The green roofs of Villa Mairea, designed by Alvar Aalto (1939)
A collage of materials among the trunks of countless birch trees in the Finnish landscape, Villa Mairea, built by Alvar Aalto in 1939, is a celebrated housing project that marks the transition from traditional to modern architecture. For the design of Harry and Meir Gülichsen’s country guesthouse, Aalto was permitted to experiment with his thoughts and styles. This freedom of creativity found expression in the Villa Mairea – radical for its time, perfect, and today one of the most outstanding representatives of the dawn of modern architecture.
The green roofs at the La Tourette Monastery, designed by Le Corbusier (built 1953-1961).
La Tourette Monastery was Le Corbusier’s last building completed in Europe and is considered by many to be his most iconic project. It was built as a secluded world for a community of silent monks of the Dominican Order, respecting their unique and specific way of life The monastery includes one hundred private cells, a common library, a refectory, a rooftop cloister, a church, and classrooms. The committee that decided to establish the building considered that the main duty of the monastery should be the spiritual awakening of the people, especially the inhabitants of the nearby areas. The only request to the architect from Father Marie-Alain Couturier was “that he creates a quiet dwelling for a hundred bodies and a hundred hearts”.
Le Corbusier inspects the construction of the green roofs of La Tourette Monastery, in the company of Dominican monks.
The Swiss-born architect, whose ideas changed the whole concept of architecture, formulated his five principles of modern architecture, to which he remained faithful for the rest of his life. One of the five principles is directly related to the green roof. Instead of a pitched roof, Le Corbusier almost always used flat roofs. In this way, the roof is used as an additional floor – landscaped like a garden. Green roofs – one of the principles of modern architecture.
Sources: www.archdaily.com / www.pro.magnumphotos.com
At the end of the 20th century, the emergence of the industrial era developed the concept of the green roof in Germany, following the innovation of H. Koch, which mixed gravel and sand with tar to achieve a non-flammable waterproof coating. With the help of nature, the new materials became the basis of the system for herbaceous plants that grow on the roof of the building. Later in the 1960s, both the sand and gravel layers were replaced with a simple drainage system and a new lightweight green roof design. Innovations and developments in roof technology made Germany the first country in the world to adopt the principle of the green roof in a building. The example was soon followed by Northern Europe and North America and later by several countries in Asia.
GREEN ROOFS IN HOT CLIMATES
The definition of hot climate in this section refers, for example, to Mediterranean, tropical, steppe climates. These climates accept green roofs as building elements or as a necessary roof garden in both traditional and monumental architecture in Asia, Africa, Eurasia, America, and Australia. The first appearance of the green roof was at Ziggurat in ancient Mesopotamia, from the fourth millennium to 600 B.C. The green roof, located in palace temples, consisted of grasses, shrubs, and trees planted on terraces of a stepped pyramid. And the most famous green roof in history was built around 500 B.C. The Hanging Gardens of Semiramis in Babylon are also famous as the world’s first botanical garden. Various species of plants, as yet unknown to the community, were grown there.
In Mediterranean civilizations, the existence of the green roof was discovered in the buildings of Pompeii, which were green islands in the heart of the city. The atrium-shaped green garden is found not only in public spaces but also on the roof of buildings. The Villa of the Mysteries (Villa Dei Misteri) is evidence of the existence of an intensive roof garden in Pompeii. The entrance of the house testifies to a roof garden, and the façade is a kind of hanging garden. The previous paragraphs have briefly presented some examples of green roofs existing in monumental architecture, used to mitigate hot weather conditions, as a recreational area, or to express the social status of the owner. Not far from the green roof concept of monumental architecture is the emergence of the dry roof in traditional, vernacular architecture. Because of the lack of water in some climatic areas, the use of bamboo, grass, leaves, and reeds as a structural element is applied in different regions, times, and cultures. The following is a comparison of different types of green roofs existing in traditional architecture in other regions and civilizations with hot climates.
A dome-shaped dwelling made of dry reeds and covered with dry grass in the lands of the Zulu tribe, South Africa. Dwellings designed with circular or geometric shapes were covered with dry grass laid on clay, stone, or reed houses. Thatched green roofs, used from antiquity to the present, were the most effective means of coping with hot weather.
In some European countries, a thatched roof is commonly used to keep indoor rooms cool. The design of the house is different in this area. As seen in the figure, thatched buildings were used by farmers in Greece as temporary shelter and storage.
Dry grass was used by the Native Americans, the Indians, as a building material even before the Spanish invasion. The grass was also laid on the steep roof to protect the palm fronds from the harsh conditions outside. Later, the Choza house adopted the square house design after the Spanish invasion or the roundhouse design borrowed from African migrants.
In Asia, dried plants are used as raw materials for building settlements in China, India, Japan, and Indonesia. A grass roof was used by villagers to cover their straight, circular, or pyramid-shaped roof. The figure shows a pyramid-shaped thatched hut in the Gulf. The thatched roof and walls were considered a successful technique for mitigating weather
GREEN ROOFS IN COLD CLIMATES
In cold environments, there are numerous examples of green roofs. Lack of water is usually not a problem in these climates. Therefore, green roofs are used as a type of insulation material to reduce heat loss from the inside to the outside. The use of dry grass in building materials in Europe dates back to prehistoric times. There are examples of the use of green roofs in Central Europe – in Germany, Poland, France, almost all Scandinavian countries, Ireland, and the UK. The existence of a green roof is also known in the construction of tombs. These simple constructions helped prehistoric nations to put their mark on landscape design. Apart from the thatched roof, the living, green roof is much more commonly used in the traditional architecture of people living in cold climates. Cool-weather allows grass to grow easily. Both roof techniques (thatched and living green roof) are widely known from prehistoric times to the 19th century in many areas around central and northern Europe, France, the British Isles, and Russia. Excavation evidence reveals that between 3600 BC and 2600 BC. the construction of thatched roofs on stone walls, straw bales, or brick walls was widely practiced. This technique proves that the green roof and the brown (thatched) roof were widespread in different types of buildings from churches, temporary shelters to houses. Even as people turned to farms and villages appeared in the period 3900-3600 BC, the concept of green vegetation and green roofing on huts and buildings continued to evolve. The following are some examples of the application of green roofs in the traditional architecture of people in cold climates.
A grass wall and a living, green roof were essential elements used during the Viking era to protect the building from cold temperatures in winter. This technique dates from 800 AD to the late 9th century. Photo shows green roofs at the Mailhaugen Open Air Museum in Lillehammer, Norway
The grass roof and walls concept was found in North America, L’Epaves Bay, Newfoundland, and L’Anse. The grass roof covering the winter house from the ground to the peak of the roof, or oval family compound, appears in the Yup’ik Eskimo in Alaska. The attached photo shows large vertical dwellings covered with grass at the Yukon River, Alaska
The photo illustrates the living grass on the roof of a home in Canada. In the 19th century, Russian migrants passed on their green roof technique to Canada. The grass walls and green roofs are shown in the dwellings of miners in the Thompson River Valley, in Canada. Dry branches and grasses on the roof were used as building materials to insulate the homes in the cold climate.