Green roofs has many positive aspects, ranging from physical health to mental well-being to recreation to reduction in energy bills. Research says that just having a view of trees and bushes from the house window contributes to overall well-being and work performance. Another study says that spending 120 minutes a week in nature contributes to well-being while also slowing down the progression of serious diseases, such as cardiovascular disease and diabetes. But not all city dwellers have the time or prioritize spending time in nature.
The initial cost investment along with the annual maintenance costs of green roofs can discourage project investors, but they provide a longer lifespan compared to conventional roofs and thus deferred replacement benefit. Additional monetary societal benefits that are “saved” or should be reduced from green roof implementation are air pollution, stormwater infrastructure, and healthcare.
One or the other?
The population growth in cities has increased and is expected to continue to increase until 2050 by an additional 60%, which means an increased risk and proportion of health-related complications.
Do we move the jungle into the cities as well to expand it to the same extent as population growth? In urban environments where there is no space to introduce green parks, concrete rooftops and building walls are utilized, and green roofs and trees are introduced, which also reduces the urban heat island effect. The urban heat island effect is the warming effect in cities due to a higher proportion of concrete than greenery. Like an urban sauna in the summer. The moisture evaporation and transpiration that occur in the green roofs lowers the heat levels.
The nurse Florence Nightingale, who treated war-wound during the 18th century and later laid the foundation for nursing education, emphasized the importance of holistic treatment of patients. For recovery and well-being, she said that people need a nice place to recuperate, sunlight, and clean air. Green plants and trees purify the air through the intake of nitrogen oxides and carbon dioxide, while also creating recreation and well-being. Buildings covered in greenery are nicer for the eyes and the soul.
Urbanization has negatively affected the land and the climate. Buildings are being built on land that otherwise could have been farmed, which in turn could have stored a large amount of nitrogen oxide and carbon dioxide that further lowers the climate and heat. The amount of heat in the city also depends on the leaf density of green roofs as well as the depth of the substrate, which stores more water and reduces heat.
Sunlight is affected by two factors. The leaf density of the plants, which absorbs more sunlight, reduces the heat, and the thickness of the soil layer. The thicker the soil layer, the greater the cooling effect released during the summer compared to thinner layers. Rainwater uptake can reach up to 70% per year, but this applies to flat roofs, as sloped roofs increase runoff. For landlords, it would lower their energy and heating costs throughout the building because it regulates them. In addition, green roofs increase the lifespan of roofs that would otherwise have required enormous investments and maintenance costs.
What do birds and airplanes have in common?
Airplanes make stopovers at airports in different nearby countries due to technical capacity limitations, such as smaller fuel tanks, among other things. Additionally, the airplane is further affected by, for example, the amount of headwind, which leads to stopovers because it consumes energy.
Birds function just like airplanes in that they need to make stopovers in parks or buildings with trees and bushes to be able to rest, intake nutrients, and reproduce. Research has shown that the continued population growth in cities, which is expected to increase by an additional 60% by 2050, has reduced bird diversity. Without the rare bird species’ stopovers and flight movements between nearby green parks and open green spaces, they become isolated and risk extinction due to their sensitivity to habitat changes. The invasive bird species that are more adapted to the urban environment become dominant. As Charles Darwin said in his theory of evolution, “survival of the ones most adaptable to change”. For their traits are better suited to endurance and changes and will thus be able to reproduce, which means more future generations of that species. It’s as if the environment filters species adapted precisely for their tough circumstances in a natural selection.
Pollinators and biodiversity
When we cultivate more greenery in the city, pollinators spread pollen among and between flowers. This is a prerequisite for the plants’ reproduction through seed formation and fertilization, from which we humans can eat fruits and vegetables. Globally, pollinators have decreased due to a smaller proportion of flowers, which affects our food supply. Insect pollination accounts for a third of our food. In order to promote an optimal habitat for them, urban city environments should be less than 50% hard surfaces. Greenery and trees are important corridors for pollinators and their habitats.
Bottom Line
Green roofs extends the lifespan of building roofs, attracts pollinators that secure a third of our food supply, creates homes for sensitive bird species, reduces the urban heat island effect, carbon dioxide and nitrogen oxide intake for cleaner air, and decreases the progression of diseases. Start growing on your roof, from lawns to fruits and vegetables, to take part in the benefits and contribute to a greener transition in cities.
References
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Green roofs photos. Green Roofs Pictures | Download Free Images on Unsplash
Krasner, H., (2023). 4 Anledningar till att flyg har tekniska stop (14 september, 2023). Flygblad för exekutiven.
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Pollinatörer. Pollinerande insekter i Sverige (u.d.). WWF. Pollinerare – Biologisk mångfald med pollinatörer
Wenzel et al. 2020. How urbanization is driving pollinator diversity and pollination -A systematic review. Biol Cons, 241:108321. https://doi.org/10.1016/j.biocon.2019.108321
