DOWNTOWN NATIONAL FOREST
Plan would festoon skyscrapers with trees, shrubs
Imagine a Downtown skyscraper or apartment building festooned with trees, shrubs, and other greenery — not only to add color to the skyline but to make a difference for the environment.
That’s the idea behind an initiative being launched by the Pittsburgh Downtown Community Development Corp. to adorn new or repurposed buildings in the Golden Triangle with trees and other greenery to create a “vertical forest.”
In some ways, the concept amounts to a pumped-up version of the living wall that PNC Financial Services Group had on the south side of One PNC Plaza for seven years before dismantling it last summer.
That 2,380-square-foot vertical garden was filled with evergreens, ferns and other plants to
create a living tapestry. The development group’s initiative will go a step further, primarily seeking to use trees to grow up the sides of buildings.
John Valentine, the group’s executive director, said the initiative would be the first of its kind in North America, although vertical forests have been, or are, being created in Milan, Italy, and China.
“This is the wave of the future,” he said.
Mr. Valentine, scheduled to announce the plan at the Pittsburgh Downtown Community Development Corp.’s annual meeting Wednesday night, said he already has talked to some developers in Pittsburgh about the idea, which is still in the preliminary stages. He said they liked the concept but were concerned about the cost.
Perhaps the most famous vertical forest is in Milan, where architect Stefano Boeri used balconies to cover two residential towers in greenery. In all, 900 trees and thousands of plants and shrubs grow among the two buildings. On flat land, the vertical forest would take up an estimated 1,729 acres.
In China, Ms. Boeri is designing the Nanjing Vertical Forest featuring two towers, one housing a Hyatt hotel. There will be 1,100 large- and medium-sized trees and 2,500 plants and shrubs on their facades. The project is scheduled to be completed next year.
The greenery is expected to provide 132 pounds of oxygen each day, while absorbing more than 25 tons of carbon dioxide each year.
Mr. Valentine said vertical forest projects in Pittsburgh could have similar environmental effects, although perhaps not on as grand of a scale. They could help capture rain water and lower building temperatures.
The goal is to create something “sustainable with a long-term positive impact on our city, something that would be friendly to the environment and healthy for residents and the Downtown workforce,” he said.
Just how effective greenery can be is on display on the roof of the County Office Building at Ross Street and Forbes Avenue. The part of the roof covered with greenery was 40 degrees cooler than that lined with tar on a hot day last July, according to Mr. Valentine and county officials.
Aurora Sharrard, executive director of the Green Building Alliance, said the advocacy group has talked to the Pittsburgh Downtown Community Development Corp. about increasing green space on Downtown rooftops in the past. She said she couldn’t comment on the newest initiative without knowing the details.
However, the alliance sees every building facade as an opportunity to do something more beautiful, more healthy, and more high performing in terms of environmental impact, she said.
Developer Ralph Falbo supports the idea but cautioned that care must be taken in determining what types of trees and plants are used. Roots of some trees can damage foundations, he noted, while ivy can loosened the mortar in buildings.
“I’m very much in favor of this but you have to be careful with what you do so it’s not counterproductive to what you’ve built,” he said.
The types of trees “will be carefully chosen to fit with their positioning on the facades in terms of height,” Mr. Valentine said.
“The plants that we will use in this project will be grown specifically for this purpose and will be pre-cultivated. Over this period, the plants slowly get used to the conditions they would be placed in on the building,” he said.
Mr. Valentine plans to meet with developers, architects, building owners, and others in the months ahead to try to get the initiative moving.
The plan not only could produce benefits for the environment and make Pittsburgh a leader in cuttingedge sustainable design, but could be glorious for the eyes, he mused.
“Think how cool it would look in the fall when the colors change,” he said.