Cities have been expanding at an ever faster rate and more than half of the world's population now lives in urban environments. The percentage is predicted to rise up to 70% by the year 2050. This calls for a massive redevelopment of the world's urban areas to accommodate the impact they have on the environment and the people who inhabit them. (1)
In this article, we explore the causes behind contemporary challenges of cities and how green infrastructure, implemented on a national and municipal level, can solve them.
Our cities are getting hotter, more crowded and noisier. One of the most pressing problems we have been facing lately are increasingly frequent heat waves – the consequence of global warming and faulty city planning. Besides the discomfort this has brought upon city inhabitants, it places great stress on human health, the productivity of workers and it also causes infrastructure problems, as explained by Tony Matthews and Jason Bryne from Griffith University. (2)
Urban heat waves affect different communities in various ways, also increasing death rates. Among the particularly affected groups are the poor, the elderly and small children. People who live in highly industrialised areas are also highly vulnerable. (1)
The main reason is population density. Cities aren't only growing in size, but also in numbers. To put it into perspective; in 1950, 746 million people lived in cities, by 2014, the number had risen to 3.9 billion and it continues to grow, with predictions of up to 6 billion people inhabiting urban areas by the year 2045. (1)
The increase in urban heat is a result of many factors. The building materials used in modern cities have thermal properties that contribute to overheating. There is also the issue of air emissions, caused by traffic and other forms of pollution. Building heating and cooling systems represent a major factor, and one of the reasons is also connected with the way we design cities, with narrow street canyons trapping heat, preventing it from cooling down at night. (1)
We also have to bear in mind the albedo effect. The negative correlation between the albedo effect and surface temperature means that the lower the albedo, the greater the surface temperature and vice-versa. To lower the surface temperature of buildings we should therefore use materials with a high albedo value.
For instance – roofs painted white have an albedo of about 0.8, but it is not easy to maintain them without regular washing. According to research, green roofs can reach an albedo of between 0,7 and 0,85, which is what makes them great at lowering roof surface temperatures. (3)
The benefits of green infrastructure encompass many areas connected to heat reduction in cities and can also act as a substitute habitat for small animals.
Hard surfaces, such as concrete and asphalt increase urban temperatures by absorbing heat and radiating it back into the environment. Green infrastructure, such as green roofs and walls on the other hand, have the ability to regulate air temperatures with its high albedo effect and through natural evapotranspiration.
Evapotranspiration is a process where plants release water vapour into the atmosphere as a result of normal plant breathing, effectively cooling the surrounding atmosphere. (2) Plants can also improve urban air quality by removing various pollutants from the air. (1)
Germany has seen the benefits of applying green roofs for many years now. The first modern green roofs in 1960s were shortly followed by technological improvements and supportive policies by the local governments. (4)
Wolfgang Ansel, an expert in the field, explains that the German model is
mixture of federal and local laws, backed by supportive subsidies, and punitive higher taxes on run-off from conventional roofs. German federal law demands that each state produce a landscape plan, and federal nature conservation laws demand compensation for environmental damage in greenfield developments, which is generally done by installing green infrastructure.
Today, Germany has between 100 and 150 million square metres of green roofs, as estimated by the German Roof Gardens Association. (4)
At Urbanscape®, we have developed systems for various different problems and uses;
We are also keen on helping local communities develop mechanism to combat negative effects of global warming through green technologies and through education on the subject and its effective implementation to ensure the most efficient use of resources.
Visit our website to find out more about our green solutions:
https://www.urbanscape-architecture.com/solutions/
Blog written by: Ana Belčič, Studio Miao
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