Going [Leafy] Green – inside and out
David Baggs, CEO and Technical Director
Background
A building without green life is a building that's letting both
its occupants and the wider community down. Plants installed not
just in but on contemporary structures produce a
wide range of benefits.
The US Green Building Council's LEED Green Building Rating
System and the new Abu Dhabi Estidama Building and Community rating
tool systems both provide significant credits for implementing
vegetated or 'green' roofs. However, at least one green building
rating system has credits for installing plants within offices. The
Green Star system, by the Green Building Council of Australia,
rates buildings on environmental sustainability criteria, and those
with suitable plantscaping within them receive points towards the
rating also.
Figure 1: The
ACROS Fukuoka Prefecture International Hall Green Roof
Source: www.metaefficient.com Architects: Emilio Ambasz &
Associates
It's all part of creating a cleaner, healthier environment. Even
buildings that are themselves very clean can be affected by VOCs -
volatile organic compounds - that people carry into them, such as
workers on their clothing, their deodorants, perfume and hairsprays
or cleaners with cleaning compounds. Indoor plantscaping can
neutralise these and clean up the air in just a few hours. Even
carbon dioxide build up can be absorbed and replaced with oxygen
rendering the air not just healthier but more conducive to mental
efficiency and concentration.
Indoor Air Quality
Worldwide experience has recently been confirmed in Australia by
research at the University of Technology, Sydney (UTS) that green
plants are an effective way of reducing VOCs in internal air.
The indoor foliage plant species:
- Kentia Palm (Howea forsteriana),
- Peace Lily (Spathiphyllum 'Petite'),
- "Janet Craig' (Dracaena deremensis),
- Devil's Ivy (Epipremnum aureum),
- Queensland Umbrella Tree (Schefflera
actinophylla,)
- "Amate' Spathiphyllum 'Sensation', 'Petite' and
- Dracaena marginate
were all tested
for their ability to remove VOCs from the indoor air. All seven
plant types studied demonstrated benzene removal activity at
similar rates. Kentia Palms were found to remove benzene up to 90%
from a closed room after 24 hours. When ventilation was added to a
room with a Spathiphyllum 'Petite' inside, the rate of
benzene removal was improved up to 15%.
Figure 3: Peace Lily
Source: beth.hohertz.org
Studies in Norway and the Netherlands have shown that health
complaints at work can be significantly reduced by the presence of
plants. Symptoms associated with Sick Building Syndrome (SBS) can
be dramatically reduced by the addition of good plant displays.
Programmes to extend the use of plantscaping within residential and
office situations and further into the retail, healthcare and
education sectors would be useful in making indoor air conditions
more healthy and improve worker productivity.
There is also a need for more research into the types of plants
that are most useful. Encouragement is needed for researchers to
look at developing varieties that will not only live well in
traditional planters indoors, but also in vertical live indoor and
outdoor walls as well as those that live on top of modern-day
buildings as green roofs
There are many reasons why the green building rating tools have
started to provide significant numbers of credits specifically for
green roof. People are realising that there are thermal
benefits, water-conserving and water-quality benefits, and benefits
in terms of stormwater detention as well as retention.
Then there's the combined thermal effect of plants when they're
on buildings - not just of the plants themselves but of the
influence they have on surrounding areas in reducing what's known
as the 'urban heat island' effect. Studies all around the world
have shown the temperature in built up urban areas are between
3.5°C and 4.5°C higher on average and up to 10°C higher on still
summer nights. When there are more plants in urban areas these
temperatures drop.
The urban heat island effect creates a 'negative feedback loop'
or 'vicious circle': the hotter the city gets the more people use
air conditioning so the hotter the city gets as greenhouse impacts
increase.
Figure 2: Green
roof and walled building in Europe
Source: greenroofs.wordpress.com
The growth in green roofs globally has been phenomenal in recent
years as city governments come to understand the full benefits.
Germany now has green roofs included in approximately 20% of new
buildings and they have been mandated in Tokyo for buildings over a
certain size.
Green roofs are even making inroads into the private sector. At
the Ford Dearborn Michigan truck assembly plant in the United
States, the entire manufacturing floor - 45,000 square metres or
approximately 6 acres of it - is under one green roof. Green roofs
are already planned in many new developments as the number of
companies solely dedicated to their construction increases.
There are 2 basic types of green roof, the traditional
'Intensive' (soil thicknesses over 6 inches or 150mm) more suited
to desert environs and the very thin or 'Extensive' roofs-
sometimes as little as 2 inches or 50 millimetres to 21/2 inches or
70mm deep overall, plus the plants. When using extensive roofs with
very thin growing media there are more restrictions in plant
selection and irrigation frequency and as a result there is a need
to have an integrated subsoil irrigation system.
The question many will immediately think is 'where will the
water come from'? The answer is simple. Along with the many other
credits in the green building schemes are credits for water
recycling particularly for irrigation purposes. Technically green
roofs can be very useful within projects that recycle grey or black
water as once these systems are introduced into a project with
onsite recycling technology, there is usually a need to dispose of
the excess healthy water and green roofs provide the perfect
multi-benefit approach to absorbing nutrient laden water than will
damage local environmental conditions if disposed into waterways,
while providing all the other urban heat island, clean air and
visible natural beauty of lush landscapes in new city environs.