Climate and city are interdependent: The climate determines how the city is used by its inhabitants; in turn, the way the city is used by the inhabitants influences its climate. High temperatures demand cooling, cooling requires energy, energy emits pollution, and pollution leads to an increase in temperature. Sounds a bit confusing, we know, but can you see how everything is connected? There are, however, simple strategies to prevent overheating of cities, as well as to reduce urban carbon dioxide emissions. Stick to these easy-to-follow steps for healthier and more sustainable cities: 1. Implement urban parks and green areas When air flows through a vegetated area, the plants reduce temperature and increase humidity through a process called evapotranspiration. Due to differences in pressure, this cool breeze is able to go beyond the park’s limits, cooling surroundings areas, as well — even small parks can be efficient cooling sources.
Dramatic before and after of the concrete plant park. Photo credit: (right) Bronx River alliance (left) Joan Byron
Trees can filter pollutants and dust particles, as well as cast shade, and therefore are of great importance on urban streets. With regard to shading, a tree’s crown shape is more important than the density of its leaves. Street trees are a great strategy, as they are relatively inexpensive and are highly accepted by citizens.
GONÇALO DE CARVALHO; credit: Adalberto Cavalcanti Adreani
Vertical or horizontal green surfaces on buildings improve energy performance and the environmental conditions of the surroundings. Annual energy consumption in buildings with green roofs are said to be up to 16 percent lower than those with conventional roofs.
The Currents; credit: www.greenovergrey.com Jacques Côté, Desjardins.
And why not involve local residents in this initiative? Offering green areas may be mainly the municipality’s responsibility, but in the case of high-density cities, urban gardens can play a major role in balancing the local climate.
Private garden designed by Amir Schlezinger ; photo credit: Timothy Soar
Water can either cool by evaporation or by absorbing heat. Water features are a lot more effective if implemented on a big scale or if the water is flowing, in movement (like in fountains or jets). Water features are particularly recommended in high-use areas, such as commercial streets or squares.
Mill River Park; credit: Olin
Sankt Kjelds square in Copenhagen’s First Climate Resilient Neighborhood. Credit: www.tredjenatur.dk
Climate change alters rain patterns, so rain water management is a very important matter nowadays. Promote the use of permeable pavements and storage infrastructures, which are beneficial strategies in case of both drought and flooding.
Related article: Copenhagen’s First Climate Resilient Neighborhood 7. Pay attention to street width-height ratio This step is closely related to the previous one. Street width-height ratio (known as canyon geometry) influences airflow patterns, increasing or reducing wind speed. Ventilation is a great passive cooling strategy, as it also contributes to the dispersion of suspended particles and polluting gases.
8. Design the urban geometry carefully Building density and geometry influence the amount of solar radiation that reaches buildings and surfaces, which can store heat and therefore increase temperature both indoors and outdoors. Although buildings cast shade, this is not an excuse to fill a city with skyscrapers — there are other preferable shading strategies, such as through vegetation and movable shading devices that can be removed in winter.
Shade structures at Al-Fayah-Park; credit: Heatherwick Studio
Evaporation in urban areas is decreased because of waterproofed surfaces. Permeable materials and vegetation allow cooling by evaporation, so avoid the use of hard materials, which accumulate heat.
Before and After of car park site. Imaged credits: Google maps and OKRA
Rough and dark-colored surfaces absorb more solar radiation than smooth, light-colored, and flat surfaces. Therefore, due to the material’s properties, the latter is preferable in hot climates.
Sunken garden view. Photography Credits Go To Eran Karu
As we have seen, the relationship between climate and city is interdependent. Achieving a healthy balance is a major challenge for urban planners and landscape architects, especially in the current context of uncertainties regarding climate change. But there are simple and effective design strategies we can use. It is important to emphasize that, when dealing with urban scale, strategies applied individually do not work, due to the complex interactions among city elements (so don’t forget that the techniques must go together for relevant results).
Recommended Reading: Design with Nature by Ian L. McHarg
Principles of Ecological Landscape Design by Travis Beck Article written by Julia Lucchese
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