11.01.2026

Ensuring Air Circulation in Cities – Planning Strategies to Combat Heat Buildup

Building design

How smart planning and fresh air concepts improve the urban climate

Heat buildup in the city, stifling air trapped between concrete facades—it doesn’t have to be this way! Smart urban planners think not only in terms of lots and parks, but also in terms of airflow. How can air circulation be specifically promoted to mitigate the urban heat island effect? What can planners, architects, and city governments really do? We’ll show how well-founded strategies, digital tools, and a dash of courage can bring fresh air back into the city—and why the issue of air circulation has long been a top priority.

Why Air Circulation in Cities Is a Key Issue for the Urban Climate and Quality of Life
Which physical and climatic factors determine air movement in urban spaces
How dense development and soil sealing turn cities into heat islands—and what that means in concrete terms
Planning strategies to purposefully create fresh-air corridors, green corridors, and open spaces
The role of building layout, street design, and vegetation in air exchange
Current digital methods for analyzing and simulating airflow in urban planning
Best-practice examples from Germany, Austria, and Switzerland that can serve as models
Challenges in implementation—from legal frameworks to public acceptance
Recommendations for planners, government agencies, and policymakers to sustainably ensure urban climate and air quality

Why air circulation shapes the urban climate—and why it is often underestimated

When people think of the urban climate, they usually think of record-breaking heat, particulate matter levels, and air conditioning. But the true heart of every urban microclimate is air circulation. Without it, warm air stands like an invisible wall between the asphalt and the attic; cooling fails to occur, and pollutants accumulate. Especially during the increasingly hot summers of recent years, residents and planners alike have come to realize just how vital a supply of fresh air and the removal of heat have become. Cities are not passive victims of the weather, but active shapers of their own atmosphere—in the truest sense of the word.

The physics behind this is easy to explain, but putting it into practice is anything but trivial. Air moves in response to temperature differences, pressure conditions, and obstacles. In a densely built-up city with tall facades, narrow streets, and impervious surfaces, so-called heat islands form. These heat up significantly during the day, store the energy, and release it only slowly at night. The result: The city remains warm much longer than the surrounding areas, and the temperature differences create local wind patterns. However, these are often so severely impeded by the built environment that the natural flow of fresh air is virtually nonexistent.

In addition, climate change is further exacerbating the problem. An increasing number of hot days, tropical nights, and extreme weather conditions are putting cities under pressure. The health consequences have long been documented: heat stress, increased mortality, and reduced performance. All of this makes ensuring air circulation a key task for urban planning. Those who ignore it risk not only the quality of life but also the city’s attractiveness and functionality.

Nevertheless, the topic of air circulation is still considered a niche issue in many municipalities. There is often a lack of knowledge, political priorities, and clear responsibilities. Urban wind conditions are too rarely considered a central planning criterion. Yet ensuring airflow is not a luxury, but a necessity—especially in densely populated neighborhoods, where every cubic meter of fresh air counts. The urban climate is not a marginal issue, but a decisive factor for urban resilience and sustainability.

Anyone who wants to design sustainable cities today must therefore learn to think in terms of wind. This requires a shift in perspective: away from purely land-use-based planning, toward a systemic understanding of the city as a breathing organism. Only then does it become clear how crucial the targeted promotion of air circulation is for a livable and resilient city.

The City as a Heat Reservoir—How Development and Soil Sealing Block Fresh Air

The classic European city takes pride in its density, its compact neighborhoods, and short distances. Yet it is precisely these qualities that become a problem in the face of climate change. The denser the development, the less space remains for natural air exchange. Building facades stand like walls against the wind, street canyons act as heat reservoirs, and impervious surfaces prevent rainwater from seeping into the ground—with dramatic consequences for the microclimate.

The phenomenon of the urban heat island has been extensively studied: Cities are often five to ten degrees warmer in the summer than their surrounding areas. The cause lies in the city’s materials: concrete, asphalt, and brick store solar energy and release it only slowly at night. At the same time, they reflect solar radiation rather than dissipating it through evaporative cooling. The result: the city “glows” well into the morning hours, and the air becomes stagnant—especially where there are no corridors of fresh air.

Added to this is the so-called roughness of the urban structure. The more protrusions, balconies, billboards, and trees narrow the street space, the more turbulence is created. While this turbulence can promote local air mixing, it generally results in large-scale air movements being severely slowed down. Closed perimeter-block developments without openings are particularly problematic. Here, there is simply a lack of entry points for fresh air. The few existing green spaces become small oases—but they are hardly capable of improving the climate of an entire neighborhood.

Soil sealing is another key concept. It not only prevents rainwater from seeping into the ground but also reduces the evaporative cooling that would otherwise be generated by planted areas and open soil. This natural “air conditioning” is largely absent in the city. The result: even more heat, even less air movement, and an even greater burden on residents. This is not an abstract problem, but a bitter reality in many cities—from Stuttgart to Vienna, from Zurich to Munich.

Anyone who looks at the current zoning plans of many German, Austrian, or Swiss cities can see the dilemma: densification is a political priority, but it is often poorly aligned with the need for fresh air and ventilation. The famous “backyards” are being densified, green corridors are being sacrificed, and transportation corridors are being planned in such a way that, while they accommodate car traffic, they no longer allow wind to pass through. Urban climatologists have been warning about these developments for years—yet there are still no binding guidelines on how to ensure air circulation.

The result: Anyone planning cities today must consciously address the interplay between building density, materials, land sealing, and wind patterns. It is no longer enough to simply build “green” or plant a few trees. What is needed are integrated strategies that define air exchange as a central planning goal and incorporate it at all scales.

Planning Strategies for Better Air Circulation—From Fresh Air Corridors to Rooftop Gardens

How can air circulation in cities be specifically promoted? The answer begins with a clear commitment: a paradigm shift is needed in urban planning, one in which fresh air is viewed not as an afterthought but as a central, fundamental principle. In practice, there is a whole range of strategies that—when properly combined—can make a noticeable difference.

The most important tool in the fight against heat buildup is fresh air corridors. These are unobstructed, undeveloped corridors that channel cool air from the surrounding areas into the city. These corridors can take the form of wide streets, parks, rail lines, or greenways. They should be consistently kept clear during the planning phase and protected from subsequent development. In cities like Stuttgart, binding regulations for this have been in place for decades—with measurable success for the urban climate.

The layout and shape of buildings also play a crucial role. Open building designs, open neighborhood structures, and strategically placed openings allow the wind to penetrate deeper into the city. Perimeter block development should be regularly interrupted by passageways, courtyards, or small plazas. Detailed flow simulations can help determine the optimal layout. Additionally, staggered building heights are particularly effective, as they can form a kind of “wind-guiding structure.”

Green spaces and bodies of water act as natural air conditioners. They not only cool the surrounding area but also create additional air movement through evaporation. Rooftop gardens and green facades make a valuable contribution here—provided they are designed on a large scale and integrated into an overall concept. Small parks, vacant lots, or planted traffic islands are also valuable components, as long as they are intelligently interconnected.

The design of the street environment should not be underestimated. Wide, tree-lined avenues promote ventilation, while narrow, high-rise street canyons block air circulation. When renovating and redesigning neighborhoods, it is therefore always important to examine how the layout and design of streets influence air exchange. Traffic-calmed areas, car-free zones, and wide sidewalks not only improve quality of life but also create better conditions for wind flow.

Ultimately, air circulation must be considered at all scales—from the overall urban development concept down to the detailed planning of individual buildings. Only when developers, architects, landscape planners, and public authorities work together in unison can a city be created where fresh air does not end at the city limits but remains palpable in every neighborhood.

Digital Methods and Best Practices—How Simulation and Public Participation Make a Difference

In an increasingly data-driven urban planning landscape, the analysis and simulation of airflow is no longer rocket science—it’s state of the art. Modern tools such as Computational Fluid Dynamics (CFD), urban climate modeling, and digital 3D city models make it possible to test, as early as the design phase, how planned buildings, streets, or green spaces will affect the urban climate. These methods not only provide impressive visualizations but also hard facts to support decision-making.

The city of Stuttgart is a pioneer in this field. For decades, urban climate assessments have been conducted here, serving as the basis for zoning plans. Digital models show where fresh air flows, where they are blocked, and what measures are needed to improve ventilation. The result: a sophisticated network of fresh air corridors, green corridors, and open neighborhoods that serves as a model for many other cities.

In Zurich, Vienna, and Munich, digital twins are now also being used to simulate the effects of new construction projects on the urban climate in real time. These Urban Digital Twins combine geodata, weather information, and traffic flows to make precise predictions. This makes it possible to run through various scenarios and find the best solution for each neighborhood—even before the first shovel hits the ground.

Another important trend is public participation. Digital platforms make it possible to visualize complex climate models in an understandable way and to involve citizens in the planning process. In this way, local experiences and needs can be linked to the results of the simulations. This not only fosters greater acceptance but also ensures that measures to improve air quality actually meet people’s needs.

However, there are also challenges. The availability and quality of climate data vary from place to place, and interpreting the models requires specialized knowledge. Added to this are legal and organizational questions: How can urban climate requirements be bindingly incorporated into zoning plans? Who is responsible for implementation? And how can we prevent economic interests from ultimately taking precedence over the urban climate? Here, policymakers, administrators, and the planning community are equally called upon to break new ground.

Conclusion: Fresh Air as a Planning Principle—An Investment in the City’s Future

Ensuring air circulation in cities is far more than a technical detail. It is a central prerequisite for health, quality of life, and climate adaptation in urban areas. Anyone planning cities today must view the wind as an ally—and guide it purposefully through streets, squares, and neighborhoods. This requires the courage to leave space, openness to new methods, and the will to critically question existing structures. Digital tools and simulations provide the facts, but in the end, people decide: Do they want a city where the air is stagnant, or one that breathes?

Examples from Germany, Austria, and Switzerland show that good planning works—when it is consistently implemented. Fresh-air corridors, open development patterns, green roofs, and innovative street spaces are not a utopian dream but have long been a reality. Yet they need strong advocates in politics, administration, and planning. The goal is to establish binding standards, pool expertise, and permanently place the issue of air circulation at the very top of the agenda.

Cities that are already investing in their “wind infrastructure” today are not only ensuring a better climate but also gaining a competitive edge in the race for talent, investment, and quality of life. They are creating spaces where people enjoy living, working, and spending time. And they prove that urban development remains shapeable even in the face of climate change—if approached with courage, creativity, and a fact-based approach.

Those who fail to address the issue of air circulation not only risk heat stress and poor air quality but also miss the opportunity to make the city of tomorrow truly sustainable. It’s time for today’s planners to think about the wind of tomorrow. Because fresh air isn’t a given—it’s the result of smart planning, bold decisions, and a new awareness of the invisible backbone of urban quality of life.

22.01.2025

Project

Co-creation instead of participation

Building design

Management

Participation versus co-creation: Would the Superkilen work better today if citizens had been integrated into the process from the outset?

Superkilen in Copenhagen has failed. The citizens as a whole use the square more as a place to pass through than to linger, even though they were integrated into the planning process through participation – according to a long-term analysis by students at the Danish Institute for Study Abroad. During the design and development process, the Superkilen planners asked citizens to suggest artifacts from their countries of origin for the new city square. Holistic planning with co-creation and prototypes would have been one way of increasing acceptance of the square.

Co-creation

Co-creation originally comes from the business world, which began to involve consumers in the product development process in the 1990s. The Leading Cities research group defines co-creation in urban development as “the active flow of ideas and information between five sectors: government, business, academia, non-profit organizations and citizens that promotes participation, engagement and development.”

What is the difference to citizen participation? Public participation is a means for planners to learn more about the attitudes and opinions of local residents and to develop new ideas. They increase acceptance for a project. Co-creation, on the other hand, involves the most important sectors of society on an equal footing from the outset.

It therefore offers citizens and citizens’ organizations a better opportunity to be truly heard and gain more influence in planning processes. Co-creation views users as proactive citizens rather than consumers, and focuses on long-term cultural change and the whole community rather than individual user groups. Where citizen participation seeks to integrate citizens’ opinions into an already prescribed program, co-creation helps future users to shape and enforce their own decisions. Co-creation is an endless process in the best sense of the word, with regular exchanges taking place between those involved.

Co-creation has a number of advantages. The public provides input and feels equal, citizens feel they are taken seriously. They become much more aware of their living environment. In return, the government has to be much more responsive and responsive to citizens and other sectors. In return, however, it saves costs because only what is actually needed and used is implemented and the risk of a new project is correspondingly low.

Prototypes

In large design projects such as Superkilen, it is extremely important to test ideas in advance before they become a permanent part of the landscape or city. It is a long way from the abstract idea, analysis and public participation to the concrete installation. The prototype should be seen as a learning tool that can be optimized and changed in the next step. Prototypes are a democratic way of dealing with public space, they also reduce the risk of a failed project and unnecessary expenditure.

The holistic approach

Combining co-creation with the prototyping approach makes it easier to explore the potential of a space. This holistic approach leads to more sustainable and vibrant places in the city. However, the Superkilen started with an assumption that co-creation and prototyping would have led to a different design. Users would accept the space better and make it more their own. Perhaps a more critical examination of the initial idea would also have been achieved.

You can read Bianca Hermannsen’s current analysis of the square here.
Robert Schäfer visited Superkilen in 2012, directly after the opening. You can read his review of the new city square in Copenhagen here.
Watch the video here to see how BIG travels with local residents to their countries of origin to select artifacts for Superkilen.

19.12.2024

Design

Heavyweight with a message

Building design

The Globo Uovo sculpture is an impressive work by stone sculptor Marc Reist and is currently on display at the Dürrenmatt Center in Neuchâtel, Switzerland. The artist made the 6.5-ton “global egg” out of white marble. In an interview with STEIN, the Swiss artist explains what message he wants to convey with his sculpture, why he only uses white marble and […]

The Globo Uovo sculpture is an impressive work bystone sculptorMarc Reist and is currently on display at the Dürrenmatt Center in Neuchâtel, Switzerland. The artist made the 6.5-ton “global egg” out of white marble. In an interview with STEIN, the Swiss artist explains the message hewants to conveywith hissculpture, why he only works with white stone and why he launched an appeal to collect eggshells before the opening.

Marc Reist: It’s a logical consequence of my artistic work and how I reflect on my surroundings by observing them. I notice how certain rules and mechanisms are similar on both a small and large scale. I never consciously came up with the topic, it just developed. I think it started in 2005.

The Globo Uovo symbolizes the world and the origin of life. Was there a specific reason for this idea?

Yes, that was in 2011. I was invited by a newspaper in Switzerland to write a few columns. I started to write about resources and food in these texts and about what bothers me: the way we deal with food, the way we deal with our environment. And during this phase, I designed the globe and then the egg. The eggs actually always resonate with me. Regularly for my wife – I only mention this in passing – for her birthday, for Mother’s Day, there are always drawings of chicken and egg. I either start with the chicken or the egg, but the egg always resonates.

Do the many openings in the sculpture also have a meaning?

The openings were created by the lines of longitude and latitude. And I found them very special as soon as I was able to work in the egg. There is a feeling of protection when you are in your human egg and you can see the outside world through these openings. At the same time, it could also be a prison. These feelings arose in me when I was working in the egg.

From a professional point of view – I trained as a stone sculptor and also took the master craftsman’s examination – I know almost all the materials. But even so, I used to only work with black stone for my shapes. And now, for years, I’ve only been working in white. For the small sculptures I make, I use a bright white marble. There is no other solution for me and for my forms. I have never used any materials with textures. They are beautiful, but not for my shapes.

But the marble for the egg has a certain texture. Was a block of 55 tons in pure white not available?

For the Globo Uovo, the stone is a little more marbled. Because this size in pure white – that would have been almost impossible and would have meant such a long wait. And the egg in this size in pure white would almost be a little too beautiful(laughs), almost baroque. That’s impossible. Visually too, it’s almost not rock anymore.

So the egg also looks much more “alive”.

Exactly, that’s what I mean. This methamorphosis of the rock, this mountain, that has to resonate.

How did the change from black to white rock come about?

That’s an interesting question. I have to go back to that. I wanted to make a really big sculpture in the 1990s. I chose a large block in Carrara without knowing what I was going to do with it. I wanted to be inspired by the material, by the block. I normally proceed differently. I have a drawing or a model and then work on the stone. But now I wanted to be influenced by the block. At the time, it was 20 tons in size. And that put an enormous strain on me(laughs). I suddenly realized that the further north the block was transported from Italy, the greater the strain in my head became. I was very blocked! And suddenly I found the solution. I then worked out a light cloth from this block. That was probably my solution, to release this heaviness in me in relation to the block. And since then I’ve only worked with white stone.

Are there purely visual reasons why you like to work with marble a lot, or is it also because of its properties?

Both, actually. My sculptures are also a matter of light. Not only with the large egg, but also with the other sculptures. The way the light passes through the opening and the edges is what makes it so good. And the properties for working are a pleasant side effect. It is easy to work with because it is so even, so homogeneous. But I mainly use marble because light and shadow are important for my sculptures.

You also want to send out a message with your art objects.

Yes, absolutely. I think that’s the greatest task of an artist. That his work is seen and heard, as the case may be. Communication is important. It makes no sense at all if I make an egg like this just to have another beautiful sculpture in a park somewhere. That wouldn’t be enough. It needs a message.

What message is that?

We have great difficulties with resources in general. This is most sensitive when it comes to food. And I really want to draw attention to the fact that people need to deal with the issue of food and resources. That a small train of thought changes.

Your sculpture is currently on display at the Dürrenmatt Center in Neuchâtel, Switzerland. Before the exhibition began, you launched an appeal to collect eggshells. What was the reason?

We had planned a performance with a dancer for the vernissage. I needed a lot of eggshells for that. Over the course of a year, people collected around 35,000 eggshells, washed them and brought them to me. Something you would normally throw away. For the exhibition opening, we laid them out on the floor of the museum and cleared paths, like a labyrinth. The dancer danced her way through it. But every now and then she made missteps on the eggshells, causing them to crack. And at the same time, with every misstep, a part of her body died. Because the shells represent our resources and if they are destroyed, the person dies too. And so she danced through the labyrinth and gradually died a dramatic death after three or four missteps.

Find out more about the project and the natural stone work in the February issue of STEIN. You can also find more information at www.stein-magazin.de/skulptur-des-monats-globo-uovo.