Wise viewers, welcome
to Planet Earth:
Our Loving Home
for the first
in our two-part series on
green roofs or rooftops
covered with vegetation
to reduce the
Urban Heat Island effect,
promote energy savings,
improve air quality,
grow fresh produce,
minimize
storm water runoff and
lessen climate change.
There are two main types
of green roofs –
intensive and extensive.
The former requires
a large flat surface area,
features many kinds of
plants including
trees and shrubs,
has greater than
10 centimeters
of soil substrate
and is high-maintenance.
The latter has
less than 10 centimeters
of soil substrate,
is generally made up of
herbs, grasses, mosses
and other types
of groundcover
and is low-maintenance.
Today we will focus on
the greening
of building rooftops
in metropolitan areas.
In large cities, skyscrapers,
concrete buildings,
infrastructure
and pavement trap heat
from the Sun, as well as
waste heat from cars,
air conditioning units,
factories and
other sources, creating
“Urban Heat Islands”
or UHIs.
This effect can raise
the temperature in a city
two to 10 degrees Celsius
higher than if it was a
vegetation-filled rural area.
The United Nations
Intergovernmental Panel
on Climate Change
states in its
Third Assessment Report,
“It is well-known
that compared to
non-urban areas
urban heat islands
raise [both] night-time
temperatures [and]
daytime temperatures.”
UHIs cause
energy imbalances,
degrade living conditions
and can also affect
local weather by altering
wind patterns, producing
clouds, fog and
humidity and changing
the frequency and
intensity of precipitation.
The extra heat generated
by UHIs can induce
thunderstorm activity.
The resulting
rapid, heavy rainfall
heated by hot pavements
and rooftops flows into
streams, rivers, ponds,
lakes, and seas
producing stress
in aquatic ecosystems.
In recent years,
global warming
has intensified
and those living in
large metros have been
especially affected by
rising temperatures
exacerbated by
the UHI phenomenon.
In 2003 a devastating
heat wave in Europe
killed 35,000 people,
many of whom were
living in urban areas.
Many structures
standing today
are energy inefficient.
For example,
a 2007 analysis of
China’s largest buildings,
comprising
46 billion square meters
of floor space
found only four percent
could be classified as
energy efficient.
Green roofs serve as
extra layers of insulation,
reducing the amount of
heating needed in winter
and air conditioning
in summer, thus decreasing
power consumption.
On a hot summer day,
the rooftop
of the City Hall building
in Chicago, USA,
a model intensive
green roof,
will be the same as
that of the surrounding
air temperature,
say 32 degrees Celsius.
By contrast, the rooftop
of a neighboring building
without any greenery
may reach almost
71 degrees Celsius.
For many years
Western European nations,
particularly Germany,
have been promoting the
installation of green roofs
to mitigate UHIs,
improve local ecosystems
and enhance the quality
of city life.
The green roof trend
is now taking off in
large Asian metros as well.
For example in Japan,
the government
at the national
and local levels
has enacted laws
to encourage
urban roof greening.
We recently visited Tokyo
and interviewed
Mr. Taro Hitokoto,
chief official
of the Green Spaces
Environment Office,
a part of Japan’s Ministry
of Land, Infrastructure,
Transport and Tourism.
Mr. Hitokoto will now
discuss one of the
Ministry’s demonstration
rooftop garden projects.
This roof garden
with an area of
500 square meters was
installed on the building
by the Ministry of Land,
Infrastructure
and Transport in 2002,
seeking to verify rooftop
gardening technology,
measure the garden’s effects
and provide information
(on rooftop gardening)
to the public.
Does it involve
experimenting with
weights of soil or
which plants are suitable
for rooftop greening?
Yes, when installing
we seek weight-saving
materials for greening
and verify which of
the various soils,
pavements and containers
are suitable.
Also, we use
environmentally-friendly
materials such as
scrap tires and paper for
the pavement material.
Ten years ago
when rooftop greening
was not yet widespread
in Japan, you started
rooftop greening
on the Ministry of Land,
Infrastructure
and Transport building.
Could you tell us about
the results of this project?
Yes. Actually,
we have data showing
that the inter-building
temperature fell when
the rooftop was greened.
How is it structured
under this turf?
First of all, there’s
a layer of light soil about
15 centimeters deep.
Beneath this layer
is a permeable filter,
through which water
can pass but plant roots
cannot pass easily.
Beneath it is
a five centimeter-wide
path for water to flow.
At the bottom is a layer
to protect the building
from intrusion by both
water and plant roots.
How many degrees did
the surface temperature
of the roof go down
through the impact
of rooftop gardening?
This graph shows
the surface temperature
during a day in summer,
and here it is when
the tiles become the hottest.
Here is the surface
temperature of the lawn.
The temperature fell
about 20 degrees Celsius.
I wonder how many
beings have increased
their presence due to
this rooftop garden.
Up to now,
180 kinds of insects
have been identified.
The Imperial Palace
is nearby and
various insects fly in
and live here
since we’ve made
a green space a little way
from the Palace.
In Japan,
local governments
offer subsidies to
popularize wall greening,
or covering exterior walls
of buildings with plants,
and rooftop greening.
We’ll next speak with
Mr. Munetaka Takahashi
about the operation
of this subsidy system
in Tokyo’s Minato Ward,
as well as the current
status of the program.
Mr. Takahashi is the chief
of the Greenery
Promotion Subsection of
the Environmental Section,
a part of
Minato’s Environment
and Recycling Support
Department.
Would you explain
the subsidy system
for rooftop
and wall greening?
Minato Ward has been
subsidizing those who
install green rooftops
since 2008;
¥25,000 (US$300)
per square meter
is the upper limit.
The total subsidy amount
is up to ¥5 million
(US$60,000)
and rooftop greening
up to 200 square meters
per building is subsidized.
The actual result last year
was 15 projects, which
means an area of about
980 square meters of
new green rooftop space
was created.
Does the subsidy
encompass all buildings
including
private residences
and office buildings?
Those that have lot areas
of less than
250 square meters
are eligible.
When a building of
over 250 square meters
is newly constructed,
rooftop greening
is required.
Thus, we limit subsidies
to buildings
over five years old
with lot areas of
over 250 square meters.
Our concept is to enable
as many people
to install green rooftops
as possible.
I understand
that in Minato Ward, the
upper limit of the subsidy
for rooftop greening
was raised from
¥300,000 (US$3,500) to
¥5 million (US$60,000)
in May 2008.
What was the reason
for this move?
Yes.
Roads and buildings
exceed 70%
of the ward’s total area.
As a way
to increase green areas
in this ward in the future,
the rooftop space
of a building
becomes very important.
In Minato Ward there is
a lot of rooftop space
on both private houses
and office buildings.
We want to increase
rooftop greening
as much as possible,
and in the case of
private housing,
it doesn’t cost much.
However, promoting the
greening of big buildings
requires a lot of money.
So, we think that
large areas should also
be eligible for subsidies.
In Minato Ward, we are
seeking a green ratio
of 25% or covering 25%
of the ward’s total area
with plants.
We are also about
to promote
rooftop gardening as
part of a focused policy.
How effective was it
to raise the upper limit
of the subsidy?
Has it contributed
to increasing the area
and the number of
rooftop gardens?
After the upper limit
was raised, we could
secure five times
the greened area of before.
How are you going to
promote rooftop gardening
in the future in order to
reduce global warming?
We would like people
to install green rooftops
as much as possible,
because it also becomes
a measure to
counter global warming.
Also, we would like to
continue with creating
pleasant surroundings for
living things and humans.
I think it’s really wonderful
for the government
of Japan to implement
such a subsidy system
for this highly necessary
and effective approach
to counteracting
global warming.
I sincerely hope
other urban areas will be
covered by green areas
in the future.
Thank you very much.
Thank you very much.
Finally we visit
Meguro Ward Office’s
green roof,
which is very elegant.
Our guide is
Mr. Yojiro Shigeno
of the Parks and
Greenery Section of
Meguro’s Urban Planning
and Development
Department.
What was the concept
behind this roof garden,
which is beautifully
designed like
a Japanese garden?
Yes, it’s a garden
designed with a modern
Japanese-style theme.
It was designed
by Dr. Kondo
of the Tokyo University
of Agriculture.
I saw a little while ago
that the trees are watered
by an automatic
sprinkling system.
Yes, this automatic
sprinkling system
depends partly
on wind power
and solar-electric power
generation.
Will you talk about
future plans
for rooftop gardening at
the Meguro Ward Office?
Yes, the Meguro Ward
is planning to build
a rooftop park at the
Ohashi junction in 2012.
We will build a rooftop
park on artificial ground
about a hectare in size,
where people
will be able to enter.
One building has already
been built, but we’ll
construct another one
in the future
to be connected
by a bridge so that people
can come and go freely.
The rooftop garden will
slope and lead to the
new nine-story building,
and the park will
slowly descend from
the building’s ninth story
towards the other
building’s fifth story.
Moreover, further ahead
the park will be
connected with
Route 246 by a bridge,
so that people can
go down to a part
which is as high as a
two- or three-story building.
This will be completed
in 2012.
Thank you very much for
speaking with us today.
Thank you for coming here.
We would like to
sincerely thank
Taro Hitokoto,
Munetaka Takahashi,
and Yojiro Shigeno
for providing us
with the opportunity
to explore some of
the cool and inviting
green rooftops in Japan.
May many more buildings
in this great nation and
elsewhere in the world
soon feature their own
gardens in the sky.
Friendly viewers,
thank you
for your company today
on our program
and please join us
next Wednesday on
Planet Earth:
Our Loving Home
for the conclusion of
our series on green roofs.
Enlightening Entertainment
is up next,
after Noteworthy News.
May your days be filled
with joy and love.
If you have a flat roof,
you plant up there.
You don’t plant
everywhere but you can
use some plastic box
or something
or ceramic box
and fill it with earth,
fill your compost
and just keep planting,
planting - very fun.
You go out and see
the whole roof is green
and edible - beautiful.
It’s really beautiful.
Peaceful viewers,
welcome to Planet Earth:
Our Loving Home
for the conclusion
of our two-part series on
green roofs or rooftops
covered with vegetation
to reduce the
Urban Heat Island effect,
promote energy savings,
improve air quality,
grow fresh produce,
minimize
storm water runoff and
lessen climate change.
Last week in part one
we saw how
the Japanese government
is promoting green roofs
to keep heating
and cooling costs down
in buildings and
make metropolitan areas
less warm, as
skyscrapers,
concrete buildings,
infrastructure
and pavement trap heat
from the Sun, as well as
waste heat from cars,
air conditioning units,
factories and
other sources, creating
“Urban Heat Islands”
or UHIs.
This effect can raise
the temperature in a city
two to 10 degrees Celsius
higher than if it was a
vegetation-filled rural area.
Today we will shift
to Formosa (Taiwan)
to see how growing crops
on rooftops can not only
bring the previously
mentioned benefits
but also provide
local communities with
highly nutritious food,
mitigate climate change
and help us treat our Earth
in a gentler manner.
Let us now visit
the National Taiwan
Normal University’s
Graduate Institute of
Environmental Education’s
rooftop agriculture
demonstration project
that serves
as a model example
of sustainable living
in an urban setting.
Will you please
introduce us
to the special features
of the roof-top farm
at the National Taiwan
Normal University?
Sure,
I will show you around.
Thank you very much.
This is
our vegetable garden.
We offer the garden
for “adoption,”
mainly to our students.
Apart from the students,
in recent years local
residents and colleagues
from other departments
on our campus have also
felt that it’s meaningful
to have a piece of land
in a metropolis
for planting vegetables.
So, we’ve opened
the vegetable garden
to all our students
and colleagues
residing on the campus
as well as the residents
of our local community
to adopt for planting.
Regarding the design
of an eco-roof,
if it’s a new building
we can take everything
into consideration.
There shouldn’t be
any problem.
But for old buildings,
load bearing
is very important.
These factors were given
special consideration
to make sure
that it could bear
the weight of the soil.
This is
a very important matter.
When building
an eco-farm on a rooftop,
load bearing
and water-proofing are
two very important issues.
We planned it
to be a self-sustaining
environment.
So, after you have
consumed the vegetables
that you grew,
we hope you will collect
the remaining leaves
to be used as compost.
Is it similar to
kitchen-waste compost?
Yes, it’s similar.
The finished compost
can be used as fertilizer
for growing plants here
in the future.
According to
the United States
Department of Agriculture,
approximately 15%
of the food
the world produces
comes from cities.
As large metros
have millions of people,
by greatly increasing
this percentage,
the environment would
benefit in many ways
including reducing the
greenhouse gas emissions
generated from
transporting produce
to these municipalities.
Another advantage
of locally grown crops is
lower fruit and vegetable
prices as transport costs
are minimal.
Humans should maintain
a harmonious relationship
with nature.
We should realize that,
excessive exploitation
of nature will cause
repercussions from her
that can severely threaten
the existence and
development of humanity.
In light of the problem
of natural disasters,
which are becoming
more frequent, I think
we should think carefully
about how to live
in harmony with nature
and refrain
from overexploitation
of our natural resources.
From the viewpoint
of sustainable living,
it’s apparent that
our concept emphasizes
sustainable recycling
of natural resources.
Without obstructing
the process
of sustainable recycling,
I think nature
will go on forever.
As a result, humans
can also live on forever!
This is
our way of thinking. Yes!
Nearly a billion people
worldwide
are malnourished.
Sadly, food
that could be directly
consumed by humans
is instead being diverted
to livestock.
Approximately 43%
of the world’s
cereal production
and 85% of all
the soy produced globally
goes to the animal
agriculture industry.
The ecological damage
caused by animal-based
foods is so severe that
a 2010 United Nations
Environment Programme
study concluded:
“A substantial reduction
of impacts would
only be possible with
a substantial worldwide
diet change, away from
animal products.”
This is the most efficient
way that we humans
can use solar energy.
Through photosynthesis
in plants, we transform
solar energy into energy
in the food
that we consume,
and again transform it
into energy that
the human body can use
for physical activities.
So this is
how to use energy in
the most economical way.
The most direct way
is making use of plants
through the photosynthesis
of vegetables and fruits
with sunlight.
So, from the standpoint
of energy use,
I believe that eating
more plant-based food
is absolutely
the most correct choice.
The cause of the recent
global warming is due
to the high concentration
of greenhouse gases
in the atmosphere.
So if we can reduce
the consumption of meat,
I think
it will be very helpful
in reducing the emission
of greenhouse gases.
Of course, from the angle
of efficient use of energy,
eating more plant-based
foods is the correct way
and to be encouraged.
Permaculture is about
harmony between
humans and nature
and seeks to design
biologically diverse,
ecologically balanced
habitats and
food production systems.
Professor Chiu
of Tzu Chi University
in Formosa (Taiwan)
teaches courses
on this subject
and is a big proponent
of growing produce
on rooftops to improve
food security and
address climate change.
If we go with nature today
while we manage a rooftop
or a piece of land,
then we’re going
with the laws of nature.
As long as we have
a correct method,
we don’t need
to expend too much effort
because this is
the direction nature has
always intended to go to,
while we humans
just follow along.
Therefore, to face
the future water crisis,
the impact of
environmental changes,
and food crises, we have
to go along with the way
nature manages land.
We can also
add some elements
that we humans need.
For example,
we can change plants
into edible ones.
This way, we’re not just
going along with nature;
we’re also
taking care of ourselves.
That’s why
we’re carrying out plans
for green rooftops.
Of course,
this is an excellent plan
because green roofs
can help reduce
urban warming,
save energy for a building,
and more importantly,
help us face future impacts.
To transform a rooftop
into a vegetable garden is
something very important.
That’s why we have to
start to build food security
and build a food forest,
an eco-friendly
vegetable garden
in our own homes.
We have to expand
this movement because
right now we’re facing
global climate change,
and our global
food supply system
is very, very fragile.
If each individual can do it,
it will help us pass
through the future crisis.
One smart idea
that has been proposed
is to use what is called
“gray water”
or used water from sinks,
bathtubs and water
fountains in a building
to water crops
growing on the rooftop.
Gray water can augment
the water supply
from a rainwater
collection system
installed on the roof.
This approach,
along with others, can
help further minimize the
environmental footprint
of a structure.
We also have to recycle
the waste produced
in our buildings or in
our living surroundings
and reuse it in our garden.
That’s why
it’s very important
to have various kinds
of compost systems.
We should have a variety
of compost systems, and
each should be connected
with the others.
It will be a lot of fun for us
to build such systems
because we use the least
resources produce the
smallest amount of waste
and achieve
the greatest amount
of recycled products.
As we’re designing
the recycling system,
every element
is important, and
each element is closely
related to the others, and
all the local resources
are completely utilized,
be it local Sun energy,
water, wind energy
or nutrients, because the
usage of them is cyclical.
So, if we can build
a society in which
every little rooftop has
its own recycling system,
and every community has
its own recycling system,
then the small recycling
systems will combine into
a large recycling system.
Only this kind of design
can help us humans
use our limited
planetary resources and
pass through the global
crisis we’ll be facing.
Rooftop agriculture
can help city dwellers
transition to
the Earth-loving
organic vegan diet,
the quickest way
to cool our planet, as the
abundant produce grown
can readily feed many
people in the vicinity.
In what other ways
can this style
of agriculture help
mitigate climate change?
Let’s hear Professor Chiu’s
perspective.
Green roofs can help
reduce global warming
in several ways.
First, they can help
reduce heat because the
soil can help absorb heat
through evaporation
Green roofs
can also reduce the solar
heat radiation gains
over the rooftops.
As a result, we can
reduce the energy we use
for air conditioning.
Second, green roofs
themselves are a greenery
indicator, because
the plants on the roof
can absorb CO2.
Therefore we can quantify
the greenery indicator
of the nine indicators
of a green building
calculating how much CO2
it can reduce.
Also, of course,
you can enjoy
the vegetables you plant.
You don’t have to buy
imported food anymore.
Normally, to produce
one unit of imported food,
we might need to spend
22 units of energy, but
if we eat the vegetables
we grow on our own,
and if we grow them
organically, we won’t
need chemical fertilizers
or fossil fuels
to produce them.
So this kind of lifestyle
can greatly help to
reduce global warming.
So, I think at this point
in time, we must
focus on self-sufficiency
in our food supply.
We don’t have
much flexibility anymore.
To attain self-sufficiency
in our food supply, we
can start from one rooftop
and expand it
to the entire community,
and then we can expand it
to an entire region, and
then we can expand it
to the entire island
of Formosa (Taiwan).
We have to develop
from the bottom up.
According to
the United Nations,
over half of humanity
now lives in cities.
It is up to government
leaders and ourselves
to use the resources
that we have such as
rooftops, balconies
and even unused spaces
in urban areas to plant
delicious organic fruits
and vegetables
and splendid trees, shrubs
and flowers.
By greening our
surrounding environment,
not only do we make
our world more beautiful,
we lessen climate change
and celebrate
the magnificence
of our planet.
Finally, we thank
Professors Chang
and Chiu for sharing
their expert insights into
rooftop agriculture and
wish them the very best
in their future research
in the field.
Esteemed viewers, we
thank you for joining us
for today’s program.
Coming up next is
Enlightening Entertainment,
after Noteworthy News.
May we all join hands
and work together
for a brilliant future.