Ecological cities

More infrastructures for pedestrians and for cycling, more trees, more energy from renewable sources. These are just a few ideas, among the myriad of other possible activities, that a city can develop to improve and become more eco-sustainable, and transform itself from grey to green. Response to the current climate crisis is also coming from large or small urban conglomerates; what is needed is not just gardens in the midst of skyscrapers or hints of sustainable mobility, but rather ambitious projects with the objective of truly improving the future that is looming on the horizon by adapting technology and urban planning to the growing needs of the population. Some cities have already embarked on a few projects heading in the right direction, to diminish the impact on the environment and at the same time enrich the quality of life of its inhabitants.

Singapore is one of these cities, ahead of its time. Indeed, the creation of the Gardens By The Bay Park dates back to 2012. The Park consists of 250 acres of green space where there are 18 artificial trees rising up to 50 metres in height with steel frameworks that house 162,900 plants belonging to over 200 species. Wonderfully functional and ecologically marvellous, all the “supertrees” are equipped to collect rainwater, and some of them have photovoltaic cells that produce the chlorophyll of real trees and capture solar energy. Gardens By The Bay represents one of many ways in which a city can increase its ecological footprint, without renouncing a skyline with spectacular architecture.

Shenzhen, in China - a crowded city of 12 million inhabitants and vulnerable to flooding - has launched a project to transform its roofs into gardens. The reason, is simple but effective: gardens can contribute to absorb 65% of rainwater and they also help to reduce pollution through the release of carbon dioxide.

But modern gardens do not necessarily have to be located on a horizontal surface. Hanging gardens have become almost more widespread and more important in the struggle to keep our cities green. As a result of the limited space that is left on the ground and the progress of hydroponic cultivation, the walls of skyscrapers and similar structures have been taken over by flora and fauna. The Bosco Verticale (the vertical wood) in Milan and Edgware Road Tube Station in London incorporate a vertical garden in their structure created by the British company Biotecture.

The creation of green areas in cities brings about more than one benefit: it improves air quality, the mood of passers-by and it can also create greater resilience to warmer summer temperatures by stimulating evapotranspiration, a process in which evaporation of water from plant leaves reduces the temperature of the surrounding air.

Excessive heat is indeed one of the latest big problems that metropolitan areas are facing. In the last decade summers have become warmer, with heat waves that last for weeks because of pollution. A complete resolution of the problem is complicated, above all at city level, but there are systems that can alleviate the situation. White cladding or white materials used not only on roofs but also on walls and even on roads can reflect more solar energy away from a building. In New York, the volunteers of the Cool Roofs Initiative coated more than 500,000 m² of roofs in a reflecting white colour, reducing the amount of CO₂ produced by 2,282 tons per annum.

"Cool Roof" is a tested passive cooling system, thanks to which buildings reflect solar radiation to keep surfaces exposed to the rays of the sun cool, simply by using materials with high solar reflectance and high thermal emittance - that is, the ability to emit heat in the form of infra-red radiation keeping the roof cool even in the sun. In Los Angeles, a city that is known as the island of urban warmth, local administration decided to apply the same principle by painting the roads with a highly reflective white paint. And speaking of roads, white is not the only possible colour. In the Netherlands, as early as 2014, a bicycle lane covered with solar panels was inaugurated.

Energy from renewable sources is a fundamental chapter when we talk about the eco-sustainability of cities. From this point of view, Italy fares well. According to the Urban Ecosystem: Best Practices 2019 Report already today there are 27 provincial capitals where, thanks to a combination of renewable resources, have succeeded in covering 100% (or even much more) of the electricity consumption of resident families. This is the result of a theoretical calculation based on the estimated production of the various technologies in proportion to the average consumption of Italian families, but in any case it gives an idea of how even today, with the technology that is available, it is possible to produce enough energy to cover the requirements of the territory. For example, in Gorizia, a fundamental role in the production of energy is played by the presence of a plant running on bioliquids to produce electrical energy at the rate of 36 MW, in addition to more than 7 MW of solar photovoltaic, 6 MW of hydroelectric and biomass, a combination that in theory renders the city self-sufficient for electricity.

And even in relation to pollution Italy is moving in the right direction, by prohibiting the use of cars in certain areas or on certain days. The case of Milan is the most significant: having established Area C, which includes the Cerchia dei Bastioni (bastion perimeter wall), there is now Area B which includes the whole urban centre where entry for the most polluting vehicles is prohibited. And while the first Area already did a good job in the years between 2012 and 2017 of reducing traffic, accidents and CO₂ emissions, the second area will enable the reduction of PM10 emissions from traffic by about 25 tons. Modena in recent years has also returned to the community a historic area such as Piazza Roma thanks to pedestrianization, and the removal of the car park that previously dominated the area.

Decreasing the number of cars will result in an increase in the use of public transport and sustainable mobility. Since 2017 it has been possible to reach the historical centre of Florence by tram from the Autostrada del Sole motorway in just 23 minutes: a project that contributes towards the reduction of traffic - tourist coaches and cars - in the city, while encouraging the use of public transport around Florence. The Bicipolitana (a metropolitan bicycle lane network) format in Pesaro is also worthy of note. This is a network of bicycle lanes inspired by the layout of a metropolitan train network with lines in different colours which has changed people’s style of mobility within the metropolitan area where one in three people now travel by bike. There are currently 11 Bicipolitana lines covering 90 kilometres and other lines are being set up, as well as others perhaps in future in other cities.

Another important topic is separate waste collection and waste management. In Italy the average annual waste collection fee is EUR 304 per family. However, in Treviso it is only EUR 185 thanks to the excellent performance of the city and its citizens in managing separate waste collection and the recovery of recyclable waste. The city model does not envisage any waste and is based on the circular economy paradigm and the “the one who pollutes pays” principle: the more waste is produced, the higher the bill. Vicenza on the other hand hosts the “Insieme” (together) co-operative society, where recycling is part of the most pressing social needs: relocating old and new categories of workers in the job market. Thanks to this approach, with 4 second-hand shops, 2 centres for processing goods for reuse and the management of 12 provincial waste collection centres, in addition to giving a second chance to 500 tons of waste, the Cooperative manages to provide training opportunities for disadvantaged workers. And all of this is done by tracking the flow of waste and its potential of usable goods, countering illegal methods of disposal and also, and above all for the benefit of the city.