Our cities get denser and are threatened by climate change. To secure liveability in our cities, we need innovative solutions in future urban design. If we turn our eyes to the sky, we will find one of them.
Roofs make up around 20-25% of a building’s total area but are often not optimally utilized. The many unexploited spaces have a huge potential. They can be transformed from being traditional roof surfaces into life-giving green oases.
Green roofs are on the agenda worldwide and play a crucial role in the future sustainable city. Here’re some of the reasons why the future of urban design is found on top of the city:
Today we see an increase in temperatures in cities around the world – up to 5 ° C – compared to surrounding areas. The reason is called The Urban Heat Island Effect. Urban heat islands occur when cities replace the natural land cover with dense concentrations of pavement, buildings, and other surfaces that absorb and retain heat.
Contrary to light surfaces such as snow or sand with a high reflection, dark surfaces such as dark buildings have a low albedo effect and, therefore, poor ability to reflect sunlight. When dark buildings keep being warm, the temperatures start to rise, and urban heat islands emerge across the city.
We can lower the risk of the urban heat island effect by turning the heat-absorbing surfaces into green roofs with vegetation. They can help reduce the temperatures in the city, mainly in tree ways: Firstly, they shade the building from sunlight and protects them against solar radiation. Secondly, during their photosynthesis process, they absorb water, and convert carbon dioxide into oxygen. And thirdly, green roofs can act as a wind shield. Furthermore, green roofs protect buildings against temperature changes and reduce the indoor temperature during summer, improving the indoor environment.
Read more about the RAAFT by Milford green roof solutions.
Problems with flooding, issues with water quality, stormwater runoff, damage to buildings, infrastructure, and ecosystems. We are looking to a future with more heavy rainfall, and the consequences speak volumes – more than ever, ways to handle heavy rain are mandatory on the future city agenda.
One of the biggest challenges in the city is the large areas of impermeable surfaces such as roads, sidewalks, and squares preventing the rain from seeping in. This is also the case with rooftops where rainfall is often led to gutters and then directly to the sewer.
Turning roofs into green roofs is part of the solution. Green roofs have a rainwater catchment system that absorbs up to 80% of the annual rainfall, which reduces the load on the city’s sewer system. If it rains a lot, the green roofs delay the water on its way to the sewers. This way, the rainwater does not reach the sewers until there is enough space, preventing the risk of flooding. The rainwater catchment system also maintains and waters plants, and irrigation systems are therefore not always necessary.
There are thousands of square meters of unexploited potential across the city. By utilizing roofs, not only do we benefit from the environmental advantages. Green roofs also act as green oases that improve the quality of life.
We can create desirable cities with high living standards by transforming the roofs into recreational spaces such as green parks, playgrounds, vegetable gardens, etc. It’s spaces like these that can give citizens a sense of community, foster social interactions, and bring beauty to the concrete environment – all aspects that add value to the city life.
Although the installation of green roofs usually involves higher costs than a traditional roof, they have economic benefits that can make up for this. Green roofs are energy efficient and reduce the need for air conditioning in the summertime and provide isolation during winter, lowering energy costs.
Studies also show how green roofs may improve property values, especially in areas with little green spaces.
Last but not least, green roofs can increase the life of a roof by protecting the roofing materials from ultra-violet radiation and extreme temperatures. In the long run, this will reduce the costs for maintenance or roof replacement. It is estimated that a well-maintained green roof can double the life of a roof.
Green roofs can be classified into three types: extensive, semi-intensive, and intensive.
The extensive roof has the most shallow depth (typically between 60-200 mm substrate) and the most commonly used plants are sedum, mosses, and grass, as they require lower maintenance and feed off rainwater. The extensive roof also has other advantages. It reduces air pollution, noise, and the pollutants that are carried by rainwater. The extensive roof is suitable for most flat roofs, as the load on the roof is small. The cost is much lower than other green roofs, making the extensive roof the most common in the city.
The semi-intensive roof is a crossover between extensive and intensive roofs. It requires a deeper substrate depth (around 150-300 mm), making it suitable for more plant species than the extensive roof. Besides mosses and grass, the semi-intensive roof is also suitable for plants species such as herbs, shrubs, and small herbaceous plants that need periodically watering. The different plant species can help enhance biodiversity and provide bees, butterflies, and other insects with better conditions in the city. The semi-intensive roof can handle more weight than the extensive roof, making it suitable for small paths and recreational spaces. This type of roof requires moderate maintenance and cost.
The intensive roof has a very deep substrate and is most commonly used for roof terraces, gardens, and parks. Here users can take a stroll or sit on benches and enjoy the greenery. The roof carries all types of plants, suitable for rooftop gardens, urban agriculture, and recreational green areas. Because of its heavyweight, the intensive roof needs to be installed in a much stronger structure. The intensive roof needs a lot of maintenance and is costly to maintain and construct.
Read more about the RAAFT by Milford green roof solutions.