A trio of mid-rise residential towers proposed by Italian firm Stefano Boeri Architetti could help clean the air in Egypt's new administrative capital city, while also providing affordable housing for that city's residents. 

Of the verdant towers, dubbed "Africa's first vertical forest" by the architects, two would contain affordable housing units while the third will contain a hotel. The trio of forested buildings is slated for a new 6.5-million resident city currently under construction roughly 30 miles east of Cairo.

The experimental buildings are proposed as part of a new town plan developed by Boeri and architect Francesca Cesa Bianchi, and could contain up to 350 trees and 14,000 shrubs when completed. The sustainably-minded town plan also envisions bringing green roofs to the district's existing buildings, in addition to erecting new, vertically-oriented plant-filled surfaces. So-called "green corridors" will link the new city together, as well, solidifying the beneficial impacts of trees, shade, and greenery at the urban scale.

The three buildings, according to the architects, could absorb as much as seven tons of carbon dioxide every year while emitting roughly eight tons of oxygen back into the atmosphere. The project is being developed with local architects Shimaa Shalash and landscape architect Laura Gatti for developer MISR Italia. 

In a 2018 interview with CNN, Boeri said, "The ability to enlarge green surfaces inside and around our city is one of the most efficient ways to try to reverse climate change," adding, "So, a vertical forest is one of the possible ways to ... enlarge biological surfaces, in the horizontal and the vertical. (The solution is) not only gardens. Why not also the side of the building?"

Alluring as they might be, in the past, Boeri's structure-heavy vertical forest approach has yielded criticism due to the greater-than-usual amount of concrete that is required to construct buildings that can support growing trees and soil. 

Writing in 2018, Treehugger's Lloyd Alter took Boeri's tree-wrapped projects to task, explaining, after doing a bit of math, "if it takes just an extra cubic foot of concrete to support the weight of that tree, it will take 11.5 years for the tree to pay off the carbon debt of the concrete that is supporting it." Writing just a month later, however, Alter softened his stance by admitting that "there are other benefits of putting trees on buildings [other than absorbing carbon] including that it's biophilic and makes us happier."

The project in Egypt is slated to begin construction in 2020 with an estimated completion date of 2022.