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  • Writer's pictureOlivia

How Are Green Roofs Essential to The “Net Zero by 2025” Pledge

Did you know that Green Roofs are an important part of the ‘Net Zero by 2050’ pledge taken by multiple nations across the globe?

Though this may sound implausible at first glance, the ground reality is far different.

Looking back a decade, several countries had cities that typically looked like a jungle of concrete with ashy asphalt, stark white corporate buildings, and in all a grayish landscape adding to the space conundrum in the cities.

Amidst this, a splash of greenery had become a necessity with the growing amount of fresh vegetables being brought into the cities. Totally a result of shrinking green space in cities.

Green rooftops, on the other hand, are a new trend that breaks up the monotony of widespread concrete roofs. Green rooftops, which have long been popular in Europe, have begun to appeal to homeowners, businesses, and even cities as an appealing way to promote environmentalism while solving the problems associated with conventional roofs.

What are Green Roofs?

A green roof is a flat or pitched roof surface with a growing medium over a waterproof membrane that is planted partially or completely with vegetation. Green walls are external or internal vertical building elements that support a vegetative cover that is rooted in stacked pots or growing mats.

Green roofs are a common feature of modern buildings in Europe, and some city and national governments even require them. Green roofs are required on all new residential and commercial buildings with rooftops larger than 100m2 in Linz, Austria, and green roof construction is encouraged in Germany by the Federal Nature Protection Act, the Building Code, and state-level nature protection statutes.

Green roofs can be especially useful in more densely populated areas, where they can compensate for the loss of productive landscape at ground level.

Green wall techniques can be used to improve the overall climate responsiveness of individual dwellings and even to treat wastewater on all types of housing in urban and suburban settings. Sydney's One Central Park apartment building has the world's tallest green wall.

Green Roof Types in Contemporary Age

Modern green roofs are typically available in two varieties: intensive and extensive.

In essence, intensive green roofs are elevated parks. With their intricate structural support, irrigation, drainage, and root protection layers, they can support shrubs, trees, walkways, and benches. A foot or more of growing medium is required for an intensive green roof, which results in a load of 80-150 pounds (36-68 kilograms) per square foot.

Green roofs are relatively light, weighing 15-50 pounds (7-23 kilograms) per square foot. They encourage hardy native ground cover that requires little upkeep. Extensive green roofs typically exist solely for environmental reasons and do not serve as accessible rooftop gardens.

Chicago's City Hall, one of the most well-known green roofs in the United States, combines extensive, intensive, and intermediate semi-intensive systems on a single retrofitted roof. The City of Chicago's Department of Environment City Hall pilot program, directed by the Mayor, launched a citywide push to support green rooftop systems with incentives and grants.

How Does Green Roof Benefit in Modern Buildings

There are several advantages to using green roof systems. Today, benefits and incentives, such as those set forth by the City of Chicago, are prompting the development of new green-rooftop projects. Prices will also fall as the American green-roof industry expands.

Meanwhile, the long-term economic benefits have already outweighed the startup costs.

Improve the drainage system

Sustainable drainage is an important component of any building because it prevents flooding in the event of heavy rain. Water has traditionally been controlled using a network of pipes connected to the sewage system. However, as urbanization increases, up to 75% of water runs off into urban areas.

Boosting thermal performance

Thermal performance is without a doubt one of the most beneficial benefits of a green roof, and it's amazing how much of a difference it can make. Poor insulation is one of the most serious issues that a typical roof faces, resulting in significant heat loss in the winter and sweltering conditions in the summer.

With the help of a green roof, all of this changes. By installing a green roof, you can improve energy efficiency while also limiting the use of air conditioning. Plants absorb the sun's energy, lowering the temperature of the roof in the summer and increasing thermal efficiency in the winter by trapping heat inside.

Helping out the environment

Carbon dioxide emissions are a major contributor to global warming, and as such, the government has been charged with meeting stringent EU targets by 2020. Green roofs are ideal for accomplishing this. According to the UK GBC, buildings account for 40% of total CO2 emissions.

Green roofs, like the point made above, reduce the need for air conditioning while also requiring less heat in the winter. CO2 is produced by both air conditioning and heat generation.

Supporting wildlife habitats

Green roofs also help wildlife and, as a result, can create a healthy habitat. While they will not directly replace ground environments, they are ideal for attracting birds and other wildlife, resulting in a thriving eco-friendly habitat.

The type of vegetation included in each green roof will support a variety of habitats. According to a study of 11 green rooftops in Switzerland, there are an incredible 172 different species.

Aiding air quality

Air pollution is still a major problem in the UK, with an estimated 24,000 people dying from it each year. As one might expect, air pollution is a greater issue in urban areas, particularly in larger cities like London and Birmingham.

Case study: Living green walls

The iconic East and West One Central Park Towers were designed by architect Jean Nouvel in collaboration with collaborating architect PTW, creating a gateway to the city's south. The innovative two towers feature ground-breaking architectural elements such as the Sky Garden green roof and Heliostat, as well as the world's tallest green walls (as of 2014), stretching 150 meters high. The building's iconic "Sky Garden'' floats 100 meters above the ground on a massive cantilevered platform that extends 42 meters beyond the East Tower (including the Heliostat).

The symbiotic and revolutionary living walls were designed by botanist Dr. Patrick Blanc and are based on his hydroponic system. Patrick Blanc's Le Mur Vegetal system is used to create the planted walls, which span over 1000 square meters and are interspersed in 23 different-sized panels across the facades of the two towers. In addition, simple wire trellising from planter boxes was installed all around the building, covering approximately 7 kilometers for climbers and trailing plants.

The 'living' green walls that wrap the One Central Park apartment building in Sydney are the world's first of their kind, spanning 34 storeys. They are made up of vertical vegetated wall panels and horizontal planter boxes with steel cables on which vegetation can grow. Because the vegetated walls lack soil, plants grow within a felt material.

To reduce weight and improve drainage, the planter boxes include soil as well as a lightweight growing medium. Plant species were chosen for their wind resistance and ease of maintenance, with the majority being native to Australia. An integrated irrigation system uses recycled water from the on-site treatment plant to water the plants.


Green roofs replace a hard infrastructure with one that's not only more efficient but also beautiful and useful. Green rooftops offer office workers a rooftop retreat and apartment residents a place to plant gardens or relax. Even non-accessible green roofs create stunning aerial views for surrounding neighbors and provide wildlife with a secluded, safe space.

The European region has already adopted green roofing and the US is also slowly adopting the same. One way or the other, this system is rapidly becoming a part of the modern city landscape and will stay for quite some time. As sustainability gains momentum, achieving ‘Net Zero by 2050’ with green roofs will be a new reality.

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