In the United States, from 1992 to 2012, we lost an average of 175 acres per hour of farmland to urban sprawl. That is an area the size of New York State converted from agriculture land to cities or suburbs in only those two decades. Accommodating population growth challenges us to create more buildings without completely zeroing out the beneficial plant life that is crucial for our health. 

In traditional real estate development, if you take a one-acre field and convert it to a 100-story commercial and residential skyscraper, you have maximized the commercial value of that property. Even where space is at its highest premium, a small percentage of modern construction projects are finding novel ways to incorporate plants and green spaces into their architecture. Could we bring beneficial green spaces back into modern cities by following their lead?

In Milan, Italy, there are many incredible architectural marvels. One of the newer additions to the architectural profile of the city isn’t a cathedral or museum. The Bosco Verticale is a two-tower apartment complex, housing about 500 residents. 

This project looks different from the surrounding buildings because it has planters all over the exterior of the building; CNN reports that there are roughly 20,000 trees, shrubs and plants now living on the outside. From a distance, they look like two towers with green beards.

‘Urban forestry’

The architect who designed the Bosco Verticale, Stefano Boeri, said his firm is committed to launching a “global campaign on urban forestry.” His firm estimates these towers in Milan “absorb 30 tons of carbon dioxide and produce 19 tons of oxygen a year, according to his research, with a volume of trees equivalent to more than 215,000 square feet of forestland.” 

In this case, the number of trees surpassed what would have been realistic in an empty lot with the same footprint of these buildings. It is also unique because the project is in the middle of one of the biggest cities in Europe.

Another famous urban forestry project is called Gardens by the Bay. This 250-acre park in Singapore has become one of the biggest tourist attractions in the world. More than 50 million people have visited the gardens since it opened in 2012. In short, the combination of creative modern architecture and an amazing garden was an enormous success with locals and tourists.

The Gardens by the Bay has taken its mission even further; it is now using a gasification system to convert carbon-based waste into syngas and biochar. Essentially, the gardens will burn organic trash to create heat, leaving a soil conditioner as the byproduct. This gasification process also helps them reduce waste hauling and lower carbon emissions by an estimated 20 percent.

In the United States, Manhattan’s Central Park is one of the significant examples of an urban green space with a value that is almost unquantifiable (take the average square foot cost of land in Manhattan, multiply it by 843 acres and you’ll have an enormous number). However, having property adjacent to the park is much more valuable than having property adjacent to a bunch of other towers. The perimeter of the park is some of the most exclusive real estate in the world.

There aren’t many major cities that can build a new 843-acre park. Some wise city planners, such as those in Manhattan, understood the value of parks early in the city planning and protected them from development. However, the tradition is to preserve ground-level green spaces and to crowd tall buildings around the edges. Projects like Bosco Verticale are merging the park view and skyscraper concepts.

Benefits of green roofs

Could you incorporate green space into a building in your neighborhood? Without hiring a fancy, Italian architectural firm, there may be a flat roof nearby that could support a green roof. A green roof can be something as simple as a few cacti or as complex as farmable planting beds from corner to corner.

There are a few traditional building construction benefits of green roofs. The look may be the initial appeal, but a green roof may provide a substantial R-value. Many factors make up the R-value of these plant beds. The criteria get as specific as the individual plant’s “leaf area index.” Arizona State University has a calculator that allows you to enter your green roof building construction details and receive an estimate for energy savings.

Vertical green spaces and green roofs are especially helpful in heavy rain events. Just like in a forest, the plant roots slow down water as it soaks into the dirt. This is the polar opposite of a membrane roof, where rainwater runs into a storm drain like water through a funnel. In Philadelphia, Circa Green designers claim that they keep 700,000 gallons of rainwater out of the sewer system every year with green roof systems.

A more complex value of green spaces is something many academic disciplines are investigating. Does a walk through a park make you happier or healthier? One of the multitudes of studies on this topic is called “Effects of Urban Green Space on Environmental Health, Equity and Resilience.” 

The researchers of this paper combed through more than 100 studies on the topic and concluded that “potential causal pathways leading to public health benefits of urban green spaces include psychological relaxation and stress reduction, improved social cohesion and psychological attachment to the home area, immune system benefits and enhanced physical activity.” Additional benefits include reductions in noise, air pollution and excessive heat.

Often considered the pinnacle of luxury, city construction across the globe has most of these attributes: tall, glass, concrete, boxy, laser-sharp lines, sterile. It may be the case that our tastes in architecture are changing. The cool buildings of the future may look mossier. Instead of fighting for a view of a park, we could be fighting for our next office tower to be the park.

Green spaces in or around buildings won’t replace all productive agricultural land lost by urbanization. They won’t solve all the problems presented by climate change, either. However, the trend of incorporating green spaces into cities seems to be an ideal combination of function and beauty. 

As cities sprawl, access to existing parks or open green spaces will be more and more exclusive. Vertical forests could be a way to bring glimpses of nature back into the concrete jungles. l

For more detailed information on these topics, take a look at these websites:

• Modern Farmer, farmland lost to development, https://bit.ly/2koTQdq
• American Farmland Trust report, “Farms Under Threat: The State of America’s Farmland,” https://bit.ly/2s8FimD
• CNN, Bosco Verticale and Stefano Boeri, https://cnn.it/2BfvLyO
• Business Insider, Singapore’s Gardens by the Bay, https://bit.ly/30pr27v
• Today, Gardens by the Bay visitors, https://bit.ly/2JqpDrW
• The Guardian, NYC Central Park’s worth, https://bit.ly/30n8mp5
• CBS3 in Philadelphia, the popularity of green roofs, https://cbsloc.al/2JAdrpO
• Architizer, sky parks, https://bit.ly/2XCu9Hp
• “Effects of Urban Green Space on Environmental Health, Equity and Resilience,” https://bit.ly/2PINWkD