Creeping into our cities

Living, breathing green walls are becoming the organic wallpaper of choice for city slickers

Issue: Sep 09

The vertical wall outside Musée du Quai Branly in Paris is a signature piece of horticultural artist Patrick Blanc
Photo credit: Patrick Blanc

Climate change has nurtured a new form of architectural design which merges the softness of nature with the robustness of modern-day engineering.

More than just ivy on a wall, bio-walls (also known as green-, living-, or eco-walls) are a fascinating new technology that has crept into the design of some high-profile buildings around the world.

Green roofs are sprouting on Ford's Rouge factory outside Detroit and atop Chicago's City Hall. Bio-walls are similar but more sophisticated. Essentially, they are vertical gardens. Plants are typically grown without soil between layers of fibrous material (such as felt or plastic mesh) that is suspended in front of a building wall. They are not planted in the ground or in planter boxes. A nutrient solution drips slowly to the bottom of the wall where any excess is pumped up and re-circulated.

Some living walls even incorporate a pool at the base of the structure that includes fish and small animals like amphibians!

Cheaper, cooler, quieter

A three-storey tall biowall with tropical flora at Queen's University in Ontario, Canada
Photo credit: Zoe Allen

Temperatures in and around large cities are higher than in surrounding areas. This heat island effect is caused by land surface changes resulting from urban development.

In metropolitan areas, the heat island effect is responsible for five to 10% of peak electricity demand for cooling buildings in cities. Some studies by the US Environmental Protection Agency have also suggested that wind and rain patterns have been altered, disrupting other systems that depend on them.

Bio-walls make cities cooler by adding thermal mass to buildings. The dead air spaces between a biowall and the building insulate the latter from the external environment. The plants also reduce heat by evaporating water from the surfaces of leaves; while the leaves in turn deflect sounds and reduce noise transmission.

A study by the American Institute of Biological Sciences has found that bio-walls have a more dramatic cooling effect than green roofs. So if the green wall technology was used extensively, the urban heat island effect could even be reduced.

Ecologically sound

A five-storey high vertical garden spans 300 meters across Singapore's Changi Airport Terminal 3.
Photo credit: Courtesy of airport-technology.com

Bio-walls, with their carefully landscaped patterns, are not just aesthetically pleasing. They've been known to attract fauna like birds and butterflies, especially if suitable native plants are included.

Biologist Jeffrey Low, who has spent the last decade researching conservation strategies, feels that such walls with native foliage could add further value, especially if educational elements such as information signboards are put up.

Jimmy Goh, a civil engineer with a construction company in Singapore, believes that biowalls could reduce the use of paints to decorate walls. "Though paints have evolved from what they were decades ago, today's paints still release petroleum-based solvents that can be a risk to health and the environment," Goh adds.

Creeping with the times

France appears to be leading the way, at least in bio-wall design. The Musée du Quai Branly in Paris is a recent project by noted architect Jean Nouvel.

The southern face of the building incorporates an 8,600 sq ft installation, designed by acclaimed landscape artist Patrick Blanc. Here, more than 170 different species of plants flourish and bloom.

The newest museum in Spain, CaixaForum, features a 24-m high vertical garden with over 15,000 plants representing 250 species. It is one of the finest examples of bio-walls anywhere in Spain.

Made in Japan

Japan's ACROS Fukuoka building with its dramatic stepped terraces and expansive green roof
Photo credit: Courtesy of MetaEfficient

Japan surely leads Asia with its 100,000 sq ft rooftop at the ACROS Fukuoka building. The 18-storey building features 15 stepped terraces that can be climbed.

These stepped platforms promote a serene and peaceful environment in the middle of the city. The green plants, waterfalls and small pools all add to the calming effect of the building's extraordinary exterior.

Perhaps inspired by the endless possibilities bio-walls have to offer, two Japanese companies are marketing a very functional system of bio-wall called Parabienta.

At US$60 per sq ft, these walls have featured along Tokyo's sidewalks and against the façade of some of Japan's commercial buildings.

A mark of commitment

The green wall will cool down ION Orchard in an eco-friendly way (artist impression)

The eco wall has been exported to Singapore, and will soon be unveiled at ION Orchard. Once up, the walls will line the mall's exterior along the footpath adjacent to Orchard Boulevard.

The wall is primarily designed to serve dual purposes. Functionally it acts as a boundary and perimeter wall. Aesthetically, it provides visual relaxation by making the façade softer. This distinguishing feature stands out aloud in stark contrast to the development, a sanctuary within the busiest streets of Singapore.

ION Orchard has received environmental awards from Singapore's Building Construction Authority (BCA) for design. The development, by CapitaLand and Sun Hung Kai Properties, received the BCA Green Mark Gold certificate for its host of green features.

They include: the use of photo sensors along the building perimeter to tweak lighting levels according to available daylight; and the use of deep planters on the retail podium's roof so that lush greenery can be planted to minimise heat transfer to the car park and podium areas below.

Elsewhere in Singapore, a five-storey high vertical garden spans 300 m across Changi Airport's Terminal 3. Visitors at the departure and arrival halls can admire the wall, which is draped with lush green vines and interspersed with four cascading waterfalls.

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