Thoughts on sustainability in cities

One of a big question in our world today is, how could we get our cities more sustainable?

Producing 70% of the global CO2 emission and consuming around two third of the worlds energy, cities are one of the main problems in terms of climate change. As the population and the size are growing, we need to create ideas and plans to make cities around the world carbon-free or at least a lot more sustainable than they’re now.

Good news is, there are many projects in different cities to fight climate change.

For example, the Dutch city Utrecht which makes most of its bus shelter roofs green. This is part of a strategy to make the city more sustainable. And the project is well recognized, other countries creating plans to do the same, and the Dutch city of Wageningen implements solar panels and green roofs on the bus stations as well.

But not only bus and train stations are options for green roofs. New skyscraper projects planning to plant trees and bushes in the facade. One of the most impressive buildings is “K?-Bogen 2“ in Duesseldorf, Germany. The building claims to be the greenest building in Europe and with around 30.000 hornbeambushes on its facade and roof, it probably is. The positive effects of the huge hornbeam hedge for the climate in the city center are impressive. The greening prevents the facade of "K?-Bogen 2" from heating up disproportionately to up to 70 degrees in strong sunlight and this heat from being returned to the surrounding air. The plants act like a heat buffer, and they slow down the rise in temperature around the new complex. The greenery also functions as a permanent energy converter. The hornbeam hedge is supplied with water and nutrients all year round by an irrigation system and the plants themselves release moisture into the air through their leaves. This creates a cooling effect, but there is more than that. The foliage binds fine dust, absorbs CO2 and produces oxygen. Only collections of fully-grown deciduous trees have similar ecological benefits.

And not only green roofs have a positive effect, white cities have it as well, not that strong, but at least… around 10 degrees warmer is a city than the land around. All the dark concrete absorbs the heat and gives it back in the air at night. In addition, the heavy traffic contributes to warming and air pollution. That is why it is often much warmer in cities than in the country. There all kinds of plants ensure pleasant coolness. They are missing in the city. Roads and roofs can help cooling down the city, as tests in the USA have shown. The city of New York, for example, has had more than 500,000 square meters of roof surfaces painted white in a "Cool Roofs" initiative so that they reflect the sunlight and entire streets in Los Angeles were painted white. According to the road authority, this should not only reduce the energy consumption of air conditioning systems, but also prevent heat-related deaths. And according to a study of the International Energy Agency, every second, 10 air conditioning systems are bought worldwide. So, until 2050, the power consumption in this area will be tripled. But white cities are nothing new. In the Mediterranean, for example, entire villages have been kept in white for centuries to keep the heat in summer as low as possible.

And what about new technology? Engineers have developed a new vertical wind turbine that will be placed in the middle of the city. The Enlil mini system generates electricity from the wind from passing cars and buses, transforming busy streets into sources of renewable energy. It also has a lot of intelligent additional functions for smart cities like Sensors which are measuring the temperature, humidity, wind strength and CO2 concentration. With this data, cities could possibly prevent or combat heat build areas in the inner city.

First steps could also be to provide more car-free areas and roads for bicycles. In this category too, Utrecht is one of the best cities in the world. But Copenhagen, Muenster, Amsterdam and others offer great infrastructure for bicycles. But there are also areas in other regions of the world which are doing more. Some studies show that cycling-friendly areas not only improve the climate in cities, but also the happiness of the people who live there.

It is not that important what the first steps are, it is more important that there are first steps! And I am sure there are a lot more great ideas out there than the few I’ve described.

In your opinion, what should be on the agenda of a city in the next few years to reduce the heat, purify the air and reduce power consumption?