Our towns and cities will need to adapt in order to deal with challenges of climate change. But to allow our cities to adapt to the changing environment, we also need to change our lives and behaviour. The concrete measures this involves and the ideas they’re based on were presented by Prof. Matthias Rudolph, Paul Eldag, Gerhard Hauber and Rolf Messerschmidt at this year’s DGNB annual digital congress.
BLOG SERIES ON THE DGNB ANNUAL CONGRESS 2023 (PART 2)
The second digital annual congress of the DGNB took place on 14 and 15 February. The event featured a variety of open discussions, providing plenty of ideas and inspiration on different aspects of sustainable building. This series of blog posts offers a look back at the event with a summary of key insights.
“It’s getting hotter in our cities and even if we’ll always stay in the same place in geographical terms, in climate terms we’re edging into hotter and hotter places. Our cities are now built and we need solutions,” demands Prof. Matthias Rudolph. This issue lies at the crux of Rudolph’s research; he is a professor of building technology and climate-responsive design in the architecture department of the Stuttgart Academy of Art and Design.
The research topic of Rudolph is Convertible Urban Shades, with a focus on microclimate strategies for adapting to climate change. The underlying idea of these strategies is to cast shadows on streets in the summer months and then open up areas at night to allow cities to cool down.
The concept of urban shading is nothing new, especially in southern parts of the northern hemisphere where shade has been used for decades. What’s new is the choice of materials used to create shade. Some solutions are based on low-tech materials such as textiles, but there are also hi-tech systems, among them convertible membrane roofs that can adapt as required. Issues that still need to be considered include material sourcing, resistance to extreme weather and how best to clean materials.
Improving the quality of outdoor spaces by focusing on the areas between objects
The advantage of shading targeted areas is that this creates liveable spaces between objects in cities, providing areas for local inhabitants and visitors to spend time in during periods of extreme heat. Besides textile shading, the ideal way to do this is to use trees, not only because they create shade, but also because surface temperatures under foliage are much more comfortable.
“Trees and textile shading can be used in individual squares and they’re good for the microclimate within specific areas. We create cool spots in the city that make it possible for everyone living there to be part of urban life,” explained Rudolph. The one thing that has not yet happened as a result of these special measures, however, is a fundamental change in urban climate.
Heightened urgency depending on the season
Urban climate is not necessarily a new issue, but it has taken on renewed momentum due to extreme weather, and this has spawned new buzzwords on the agendas of cities and local authorities. We now hear talk of trees suffering from ‘drought stress’ and ‘cities at risk of heat stress’. One solution to this: sponge cities.
However, we do need to remember that perceptions are always subjective, and people feel differently depending on the season. People are more willing to think about and sign on to shading during heat waves than in the winter. Not only that, but you also need to take into account where people live. According to Paul Eldag, who heads up building land development at Niedersächsische Landgesellschaft, much depends on whether you live in an urban environment or the countryside, which is also why communication with all kinds of stakeholders is key to the success or failure of climate adaptations.
Thinking differently about water
“Sponge cities are a feasibility with the infrastructures we have now, but they present many challenges,” emphasises Rolf Messerschmidt, architect and urban planner at Eble Messerschmidt Partners. “We need to redefine spaces, think judiciously about where trees and plants are an effective solution, and consider how to integrate buildings that have already been built into such measures.” Above all, says Messerschmidt, it’s essential to tackle the issue of water. “Topics like recycling greywater need to be central to these considerations – especially new ways to recirculate water.”
For this reason, Gerhard Hauber, Managing Partner at Ramboll Studio Dreiseitl in Überlingen, calls for overall hydraulic assessments to be integrated into the planning process – from the very beginning. Why? Because often, at the times we need water most, it’s not available in the same volumes as rainwater, for example. He therefore focuses on greywater when conducting assessments, because that’s always available and thus supports more reliable water cycles. “Low-water plants, flora that can do without manmade irrigation – they’re the goal. But that’s not so easy to implement because especially in cities, plants have to deal with extreme demands related to things like soil conditions or pollutants from exhaust fumes. Also, often plants and trees don’t have the time to establish themselves in peace, Hauber added.
What do we want life to be like in the future?
“Many of the measures we’re already taking today, or will embark upon in the future, will eventually result in this depiction of sustainability,” said Eldag. For this reason, he believes it will be important to seek acceptance when it comes to climate neutrality and climate adaptation in rural communities, towns and cities. People are making more demands and they want more, and that’s an important step forward. The DGNB initiative on climate-positive cities and communities will help with this by calling for sustainability to be actively supported in practice, by promoting concrete climate protection and by fostering a better quality of life in the community.
As Rolf Messerschmidt emphasises, the key to urban redevelopment lies in communication and participation. He also believes that we need to raise more awareness for climate issues – and not just when things become acute, because this only leads to quick-fix solutions, not sustainable ones.