Green roofs cool the city. Research and practice prove it

We regularly flee the city centres every summer to escape the unbearable heat. However, the phenomenon of the so-called “heat island”, which arises in densely built-up areas, represents a real problem that, in addition to higher temperatures, also causes air pollution and less precipitation.

green roof

The solution can be to plant pieces of greenery in endless concrete areas. So-called green roofs are becoming increasingly popular, thanks to which nature gets into the centre of modern city life. How can green roofs help reduce heat islands, and what other benefits do they offer?

What is heat island?

You may have heard the term “heat island” before, which refers to the centres of larger cities affected by extremely high temperatures in the summer. It doesn’t always have to be an outright “concrete jungle” in the style of New York – people flee from the heat in the summer to the countryside or the water, even from London or Manchester.

How green roofs can help cities:

City firehouse

The cause of urban heat is a large proportion of built-up and paved areas, which absorb a large amount of heat from the sun and subsequently release it into the surroundings. “During the day, the temperature difference in the city centre compared to the surrounding countryside is 1 to 3 degrees Celsius, but in the evening, it can reach up to ten degrees,” says Mr Josef Hoffmann from Isover, Saint-Gobain. Higher temperatures impact not only the physical and psychological well-being of the city’s inhabitants but also the quality of the environment, not to mention higher costs for air conditioning in buildings.

Thirty times higher dust concentration

The existence of a “heat island” negatively affects the amount of precipitation in the city and its atmosphere. It was overheating leads to the rise of warm air, which lifts dirt from the ground and accelerates smog formation. Compared to the forest ecosystem, the urban atmosphere has a ten times higher concentration of sulfur dioxide, twenty times higher concentration of carbon dioxide, and even thirty times higher concentration of carbon monoxide and dust. All these particles are harmful to human health.

Green roof helps

Green roofs are an investment in the future. From the experience of Hamburg, where the issue is intensively addressed, it can be unequivocally confirmed that they improve the urban climate, retain rainwater, bind pollutants and reduce noise pollution. A green roof creates a more pleasant building climate and helps save energy costs for heating or air conditioning – says Mr Tomas Sysel from the Institute of Healthy Living.

Cure of fever

“The only answer to these problems is to create a network of elements in city centres that are in harmony with nature, i.e. so-called green or blue-green infrastructure,” explains the expert from Isover. Blue infrastructure in the form of ponds, lakes, streams or retention tanks primarily serves to retain rainwater, while green infrastructure also helps to increase urban biodiversity.

Source: dumazahrada.cz

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