Winner | Asian Digital Media Awards 2020

Urban greenery sprouting atop city buses in Spain

An environmental landscape artist has devised a simple solution to different urban issues such as increasing carbon emissions and loss of green spaces via a roof garden system on public transportation

Spanish landscape artist Marc Grañén has devised an eye-catching rooftop garden system for city buses as a way of spreading his appreciation for nature, and currently, a prototype bus is shuttling tourists back and forth a camping site in Estartit, a town near the city of Girona in norheastern Spain.

Called the Phyto Kinetic roof garden system, the mobile garden is designed to create pockets of greenery in cities, improving the urban landscape and boosting photosynthesis to clean the air.

According to the European Environment Agency, in 2010, more than three-quarters of Spain’s population lived in urban environments and a significant proportion is intermittently exposed to high concentrations of pollutants. 

The advantage of the Phyto Kinetic system is the use of existing spaces, specifically the roofs of city buses, in increasing the amount of green areas in the city, which helps alleviate air pollution, Grañén explained to Robin Horton of Urban Gardens, a website on city life and nature, who first covered the system.

On top of a bus, a perforated stainless steel grid system is installed with a thin, lightweight hydroponic foam and sedum carpets. These components replace the use of soil and fix the garden in place, taking into consideration the technical aspects of both garden and vehicle. For example, the grid is shaped according to the roof of the bus, accounting for antennas, air-conditioning and emergency exits.

Grañén also noted that the Phyto Kinetic was designed to pass all control and safety tests imposed by European public transport regulations. The weight of the garden and its effects on sudden braking or even road accidents were carefully studied. 

Once the bare structure is mounted, small shrubs can be planted depending on the preference and creativity of the city government, transport company, or corporate sponsor. Plants like aromatic herbs, ornamental plants, ivies and different types of grass can be planted, and company signboards or logo can also be placed, he explained in an effort to encourage business partnerhships. He said, “These types of plants can be found everywhere in the world, but it is important to consider each city’s weather in determining which varieties to use.” 

As for watering the plants, Phyto Kinetic uses condensation from the bus’s air-conditioning to irrigate the roof garden, giving purpose to a commonly wasted by-product.

Alex Puig, a green wall expert in Catalonia, helped Grañén in creating this roof garden system, providing added technical expertise and the roof garden materials. 

According to Grañén, several other experts assisted in developing the system, such as a mechanical engineer from a big automotive firm. He said, “All these people have worked with me gratis because they trust and believe in the project.” 

Phyto Kinetic not only provides public transportation with “ecological and tourist appeal” but also increases carbon dioxide absorption, he wrote on his website. 

He added: “The lungs of a city must grow at the same rate as its population, but much needed green areas are not always available. Phyto Kinetic has grown out of this supposition with the goal of delivering a practical and tangible solution.” 

The roof garden system, he explained, also aids in energy reduction. During a test in the middle of summer, the Phyto Kinetic bus came out 3.5°C cooler than a regular bus. “Madrid, for example, has more than 2,500 buses. Imagine how many more are on the streets of New York City.” Approximating a bus roof size at 20 square metres, the landscape artist pegged the total amount of possible green roof space in New York City at 100,000 square metres. 

Currently, Grañén, who won the 2012 Iberflora Award for Best Sustainable Initiative, is in talks with a major auto company to fund an entire fleet of Phyto Kinetic buses in Barcelona. He also recently partnered with a Barcelona landscape design company to install the system on their vehicles, and come September, he will bring a Phyto Kinetic bus to the World Green Infrastructure Congress in France.

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