Ivy creeping up the walls of homes and buildings, often seen on the oldest of homes thought to be deserted by humans and redeemed by nature, has long been admired. But a new trend has emerged that is anything but ancient.
All over the world, buildings covered in vegetation and greenery are surfacing. There’s One Central Park in Sydney, Bosco Verticale in Milan, and Oasia Hotel Downtown in Singapore, just to name a few.
Critics have caught on, wondering why they keep seeing yet another building covered in plants or trees, but it’s hard to argue with the reasoning. Architects and planners are ‘going green’ because of its environmental benefits.
Global engineer firm Arup recently published a study that revealed why the trend is so great. As cities get denser, green space at street level dissipates. This makes it important to find innovative ways to make up for that loss, like buildings using built-in greenery to draw in carbon, purify the atmosphere of air pollution, keep cities cooler, and reduce noise.
The urban heat island effect that occurs in many cities during hot days involves buildings and roads radiating heat, causing these areas to become much hotter than surrounding, less-developed regions. And the problem will only worsen as years go by, with climate change raising temperatures and cities becoming more populated. Plants, however, can create the much-needed cooling effect by absorbing the sun and shading buildings, and through evaporation.
By modelling the effects of greenery in numerous cities, Arup engineers concluded that green facades are most beneficial in extremely dense and tall neighbourhoods, like the center of Hong Kong. In more sprawling cities such as L.A., it’s best to plant greenery at street level. The team also found that green facades are less helpful in cities that already have plenty of parks.
In dense street canyons, green coverings can reduce the presence of other pollutants in the air like soot and dust. Research shows that a simple plant on your desk boosts the quality of air in your home.
And because sounds bounce off hard surfaces, plants on buildings can lessen urban noise pollution. When modelling how various blocks are affected by noise, the engineers discovered that facades had the ability to reduce sound levels by as much as 10 decibels, and worked best at a distance from where the noise occurred.
The report found other benefits of adding greenery to buildings, too. Green roofs were shown to help collect stormwater, which keeps sewer systems from getting overworked. Greenery was also found to boost people’s mood and productivity. The greenery on buildings also gives new habitat for wildlife, leading engineers to advise people to start considering walls as “urban cliffs” to house various species. And green walls like those on a building covered in algae can even serve as power sources.
The report urges for city infrastructure to be redesigned to accommodate our changing future. And they acknowledged how building surfaces can be a great resource:
“Green building envelopes can contribute significantly and thus become a default design approach for building design. This will require a significant rethink of current design considerations, but if we can make health and well-being a starting point for all building design, we can shape a better world.”