Will sky gardens take over U.S. buildings?

Due to continued urban growth, cities are under pressure to find new ways to include green space. In addition to allowing residents to relax outside, this also helps to control air pollution, stormwater runoff, and general environmental quality.

Green roofs and sizable, ground-level gardens are the main ways developers are incorporating this trend into projects today in North America. Green roofs can improve a building's insulation, lowering energy costs. Additionally, a thick layer of vegetation can keep sewer systems from overloading during heavy downpours. Many local governments even give tax breaks to property owners with such features.

In other parts of the world, especially those with tropical climates, vegetation is climbing the structure. These plant-filled crevices in highrises add more green space to crowded cities. Although they are gaining popularity outside of that area, whether they will establish themselves in the United States is still being determined.

What is a sky garden?

According to Tim Johnson of Miami-based Fernando Wong Outdoor Living Design, Singapore significantly accelerated the trend toward sky gardens, which feature lush greenery incorporated into a highrise's common areas, particularly inset into the facade. Johnson stated, "You've got to replace 100% of the [destroyed] landscaping if you build something there." Due to the island city-state's limited buildable land, this frequently necessitates adding green space to the building itself.

Singapore encourages building owners to add vegetation to their designs. The Green Mark building certification, similar to LEED but tailored to the significant air-cooling needs of buildings in the tropics and subtropics, is required for new construction in Singapore. The Skyrise Greenery Incentive Scheme, which provides funding for such projects, and the Landscaping for Urban Spaces and Highrise program, which coordinates numerous such initiatives in Singapore, are additional initiatives.

According to Johnson, the resulting gardens provide community space for locals who are used to multigenerational living, frequently in apartment-style accommodations, in addition to their environmental benefits. Elevated gardens also offer a cross-breeze opportunity, which means less air conditioning space. That presents the possibility of energy savings in a hot and muggy climate all year.

Would this work here?

Because of the low energy prices in the U.S., building owners would not be motivated to invest in such opulent features simply because air-cooling costs would be reduced. Johnson said that cisterns that collect rainwater and use it to irrigate plants might spark interest in water-conservation areas. Additionally, owners may ask that sky gardens be incorporated into tower design to meet the requirements of a building certification program like LEED.

However, the value of sky gardens in this situation is still being worked out.

Moving vegetation from the ground to the top of a highrise is not a very sustainable idea, according to Chris Mutter, project manager at the Atlanta-based landscape design firm HGOR. Every time you raise your voice, you hear the word "sustainability," but he said these ideas run counter to it. Because the sun will dry the vegetation more quickly at higher altitudes, more water is required, so sustainability would play a role in the irrigation system selection. 

Sky gardens are widespread in tropical and subtropical regions, where it rains frequently and naturally irrigates gardens. Another factor that might restrict where in the U.S. exterior vertical greenery is worthwhile is the requirement for a consistent climate to support vegetation that maintains itself year-round. According to Maureen Baker, an associate at Mancini Duffy in New York City, sky gardens may be feasible in temperate climates like California or tropical and subtropical regions like Florida.

However, according to HGOR Project Manager Lauren Standish, "sky gardens" are likely to be restricted to green roofs or building atriums across the nation for the time being.

That's due, in part, to the fact that American cities aren't yet as congested with people as Singapore and other Asian cities are. On the other hand, she claimed that many cities, such as Atlanta, have room to expand and have thus not felt the need to build vertical parks and other green features.

Maintenance, according to Mutter, is another difficulty.

Mutter said you can design the most beautiful thing for an office tower or condo tower, "but you have to be able to have someone take a mower to it." Due to limited physical access, the necessary landscaping tools cannot be carried up to terraces and other gardens throughout a building. Plans for such spaces might become impossible as a result.

Utilizing resilient, natural vegetation might ease some of that weight. As a continuation of their counterparts on the ground, sky gardens have a natural wildness that contributes to their beauty, according to the author. In many ways, they shouldn't be made to require a lot of maintenance; doing so lessens the pleasure of enjoying vegetation that is so high in the air.

Plans for vertical gardens can also be derailed by wind.

"If you have [green space] on a five-story-high building, it's very different on a skyscraper," Wong observed. He continued by saying that a tower-high garden might require a feature like a glass shield to shield plants from strong winds.

Baker, this is especially true for vegetable gardens. Without a designated team or responsible party, "[they] require a level of attention and participation that can be difficult to come by," she said. Although many successful ground-level co-op gardens exist in New York City, "trying to recreate that kind of experience 40 stories up in the air could create complications," the speaker said.

The term "sustainability" is bandied about whenever you're in the air, but these ideas counter sustainability.

 

Mr. Chris Mutter

HGOR's project manager

According to Baker, there is an increasing desire to grow one's own food or at least to be aware of its source. Therefore, it would not be surprising to see building occupants willing to tend to a more extensive garden in the future in exchange for its advantages. That would encourage support for sky gardens.

Depending on the project's goals, there may or may not be a move toward adding vegetation to the facades of North American buildings. 

"The opportunity is about creating the experience," said Mutter. There is no distinction between being in the air and being on the ground.

Baker is unconcerned. "The desire to find something green and alive in a city built by stone, concrete, and metal is not unique to any one place," she said. "It's in our nature,"