Our passion for the environment is changing the face of urban
design - just look at the explosion in popularity of green roofs in
city centres. Instead of concrete and other roofing materials,
architects and designers are increasingly creating roofs covered in
living vegetation. Not only do these look incredible, they also
boast near impeccable environmental credentials.
While town planners and mayors are increasingly looking to
include them in new commercial developments, the obvious drawback
is that green roofs are often invisible from ground level. To my
mind, it's the next evolution in sustainable design - the lesser
known "green wall" - that will leave the most noticeable mark on
our cityscapes. In time, advocates hope that these will
dramatically improve the health of our cities, indoors and out,
from skyscrapers to housing.
Beauty and functionality
It was the sheer beauty of green walls, also referred to as
"living walls", which first aroused interest in the 1990s. Today it
is their profound sustainable value to buildings and habitats that
most excites designers. There are many benefits - green walls cool
buildings in summer, retain heat in winter and reduce noise
pollution. They also attract wildlife to areas that would otherwise
be sterile concrete and glass. They are incredibly efficient at
cleaning pollutants outdoors and in - and of course their exuberant
displays simply make people happy.
A short history
Green walls started to attract attention in the mid-1990s when
Patrick Blanc, an esteemed French botanist, began exhibiting his
creations at flower shows. He specialised in plants that grew
without soil on the side of rocks and tree trunks, and used this
knowledge to conceive the first vertical gardens. Green walls are
grown hydroponically - in other words, they don't use soil. The
plants are instead grown in pockets of felt or rockwool, and fed by
nutrient-enriched water. There is a vast plant choice, and this has
enabled subsequent pioneers in France, the UK and Canada to design
ever more stunning creations. However, the overall attitude is that
beauty is only skin deep, and that the main function of a green
wall should be to deliver environmental and social benefits.
Indoor air pollution
One of the interesting revelations about green wall systems has
been the improvement in air quality they can provide. Green walls
can be used together with air conditioning systems that draw air
through them as part of a biofilter, which helps to clean polluted
air. Natural microbes living on and in the plant roots break down
the pollution, turning it into food for the plants.
The future
With energy supplies likely to dictate the future of urban life
and architecture, buildings that need less energy will become
increasingly attractive. The new green walls being developed today
require much less water than earlier models. This can come from
grey water systems, which would also supply the nutrients, and
could be combined with rainwater, removing any dependency on mains
water.
As green walls increase in popularity among architects, the
pioneers share the preferred view that the future must involve
working with local councils. This way, green walls will reach areas
with public housing, train stations and even car parks. They also
believe that we'll see them used for urban food production too. At
present, the high costs of creating green walls make them viable
only for commercial buildings. But with demand soaring, it may not
be too long before more economical systems are developed for
private use. Until then, we can celebrate the fact that whenever
one is 'planted' in our community we all benefit from it one way or
another.
Adolfo Harrison is director of sustainable garden design
company Templeman Harrison.