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How to make Mega-Cities Energy Efficient
Hitoshi AOKI Mr.*1, Yoshitaka AOKI Mr.*2
*1 Chief Researcher, Research & Development Center,
Tokyo Electric Power Company, Japan (e-mail:[email protected])
*2 Manager, Corporate Marketing & Sales Department,
Tokyo Electric Power Company, Japan (e-mail:[email protected])
Abstract:
Tokyo is a Megalopolis with 40million+ population. It has an energy efficient profile
due to its uniqueness as extensive mass rail transit networks, high density and compact
urban formation, compact space oriented life style. The other feature is extensive use of
electric heat pumps (EHP), which entails low carbon city profile. Further possibility is
prepared with water thermal energy utilization thorough EHP, which is widely available
particularly in Tokyo central districts, which could make Tokyo one of the lowest
carbon cities in the world. Emerging mega-cities are expected to learn from Tokyo’s
success and not from western conventional models.
Keywords: Electric Heat Pump, Water thermal energy, Compactness
LEARNING FROM TOKYO MEGALOPOLIS’ STORY
Best way to get correct answers is learning from Successful experiences. Tokyo is a
real mega-city, of which population is more than 40 million. Tackling with this
population explosion, it succeeded in housing 40+ million inhabitants with providing
for necessary housing with mass transit transport services.
It is still staying as an Energy efficient Mega-city
with keeping a low- energyconsumption profile if compared with other developed countries’ Mega-cities.
TOKYO AS AN ENERGY EFFICIENT CITY (MERIT OF COMPACTNESS)
First reason is that it is well equipped with mass transit rail systems, which
substantially reduce transport sector energy consumption. People walk or bike-ride to
stations and/or bus stops. Location Preference to the Vicinity of near-by Railway
stations is outstanding. In Tokyo region, homes located beyond 800m radius from
railway stations substantively lose market values. In this context, Transit Oriented
Development (TOD) Concept is already in place in Tokyo Megalopolis areas.
Second and unique reason is that its urban formation is based on compact building and
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infrastructure design and compact city formation as a whole. Narrow and densely
installed road networks based on man walking and small scale land-lots and small scale
& low rise individual buildings are well accepted by Tokyo people. In this context
Tokyo is identical to Edo. If much more spacious building, road and park designs were
adopted, its population density must have been reduced to a much lower level and its
city form must have been transformed into a more sprawling formation.
Third and very unique reason is that it succeeded in sustaining its population density
level of 8,000 population/ km2 throughout its development process from EDO to now.
Due to these facts, TOKYO still remains as an Energy Efficient Compact City.
HOW WAS EDO?
Edo was totally dependent on Walking and Man pulled / pushed carriage transportation.
Even horse carriage was not commonly used. That is the reason why the width of roads
was relatively narrower than then European and American cities where horse carriage
and horse tram were widely used. Fig1 below shows one of Edo’s theater districts filled
with theater goers. You could not find any horse carriage. If the scene is in then Paris’
Opera district, “Rue de l’Opera” must have been crowded with horse carriage.
Fig2 & 3 show all kind of transport was man powered not horse powered.
Fig1: Crowded Nihonbashi Theater District’s Main Street
©Eisuke Ishikawa EDO & TOKYO; 0 K calorie world VS 100.000 K calorie one
published by Kodansha in 2008
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Fig2: Kago =
Two Men Borne One Seat Carrier
©Eisuke Ishikawa, Ditto
Fig3: Daihachi-guruma = Man Pulled / Pushed Carriage
©Eisuke Ishikawa, Ditto.
Fig4: Man Rowed boats hasting to Nihonbashi Fish Market
©Eisuke Ishikawa, Ditto
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EDO’S CITY SIZE AND POPULATION DENSITY
City size was restricted by human walking distance. Man’s walking velocity is about 4
km / h. Daytime is about 10 hours a day. For walking to destination, spending 2 hours
for trip objectives and walking back to origin within 10 hours, 4 hours to be the upper
limit of one way itinerary. This makes 16 km ( = 4 hours X 4 km / h) to be a city width
benchmark and 256 km2 (= 16km X 16km) to be a city area benchmark. South-east
quarter of Edo was eclipsed by Edo bay, Edo’s area was about 200km2. Its population
was about 1.5 million. Population density of walking distance city Edo accordingly was
about 8000 persons / km2 level (= 1.5 mil / 200 km2).
THREE POSSIBLE COURSES OF POPULATION DENNSITY CHANGES
Starting from EDO with 1.5 million population, Tokyo agglomeration has grown to a
contemporary Mega-city of 40 million population. In this course, how could be its
population density changes. There could be 3 possible courses as follows;
1) Increase if territory is contained as in Singapore
2) Stable
3) Decrease if territory constraints released as Motorization did in US cities
FROM EDO TO TOKYO TRANSITION CASE
From 1.5million population EDO, Tokyo had evolved into 15million population
Megalopolis by mid 20th century. Urban areas expanded substantially as shown in
Fig5.
Fig5:
Transition of Tokyo
Megalopolis Areas Expansion
from 1880 to 1953
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TOKYO’S RAPID EXPANSION IN THE SECOND HALF OF 20TH CENTURY
Tokyo Megalopolis Population increased from 15 million of 1950 to 40 million of
1995 under the rapid economic growth and population concentration to Tokyo region.
Tokyo region had been facing a great burden of housing this vast population inflow. It
succeeded to provide for necessary number of houses and never caused homeless
situation of residents. While its territory had substantially expanded into a typical
sprawling city form but mass transit dependency had never changed. Due to this, Tokyo
Megalopolis built-up areas are contained in 4000km2 level if compared with Edo’s
200km2.
POPULATION DENSITY HAVING STAYED EXCEPTIONALLY STABLE
In sum, Tokyo Megalopolis population increased from 1.5million to 40million.
Built-up areas expanded from 200km2 to 4000km2. And population density had been
staying at 8000 to 10000 person / km2 level.
This phenomenon could be translated as “20 times of Dense & Small & Sustainable
EDO makes Dense & Mega & Efficient Tokyo Megalopolis”. It is very unique and a
kind of miracle in urbanization histories.
This density stability was deprived of following facts;
1) High dependency on mass-transit transport systems, which restricted urban areas
only in walking distance vicinity of rail-way stations or bas stops
2) Road system based on human walking and bike riding and not on motor vehicle
transport, resulted in compact city structure
3) Fair distribution of wealth leading to small land plot sizes, resulted in compact city
formation as well
4) Building style of small scale & low rise individual structures maintained
WHICH STYLE OF URBANIZATION REQUIRED: TOKYO VS US CITIES
At this moment, urbanization is ongoing mainly in emerging economies and
population giant countries as China, India, Nigeria and so forth.
The issue is that these countries seem to be following the American style urbanization
patterns which are heavily dependent on individual motor vehicles and extensive
auto-route network for them.
This is evident that motor vehicle dependent cities are great consumers of gasoline.
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Fig6: Cities’ per capita Gasoline Consumption @DTER 1999
Annual par capita gasoline consumption
(mj)
80,000
US cities
San Francisco
New York
Aussie cities
Euro cities
Tokyo
Population density per ha (Source: DTER 1999)
Fig6 reads Tokyo’s par capita annual gasoline consumption is the least among
developed countries’ cities, far less than US, Canadian and Aussie cities. This fact is
exclusively due to de well developed commuter rail-way networks of Tokyo.
Interesting is that Tokyo initiated commuter rail-way construction in 1930’s when New
York as well started the same scheme. If so, why has the stark difference in par capita
gasoline consumptions resulted? The reason is New York changed its transport strategy
from rail-way based one to the other based on Ford T-type motor cars and Inter-state
Highway networks in the context of New Deal Policies designed to lift up US economy
from Great Depression. Japan and Tokyo were also mired in Economic Depression but
could not afford to change their transport strategy to motor vehicle oriented one because
of the economic constraints for importing costly oil from abroad then having had to
stick to electric railway systems sustained by coal burning power stations and hydro
power generation. At the moment, even bus transportation was restricted by the
Government due to oil scarceness. Fig7 & 8 show Tokyo’s actual status of intensive and
extensive rail-way networks and how Tokyo people utilize rail-way mass transit in their
daily life.
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Fig7:
Tokyo’s Commuter Train Networks
Fig8: Modal Sprit in Metro Tokyo @ Person Trip Survey 1998
This is a kind of irony that then oil-thirsty poor Tokyo is now scoring high on the scale
of energy efficiency and oil rich New York is rated low.
We have to learn that under the current CO2 emission reduction requirements,
emerging Mega-cities should follow Tokyo style urban transport strategy, which is
based on mass transit rail-way systems, and have to avoid adopting US style car based
systems. Unfortunately emerging Mega-cities seem to be following the US suites.
HUMAN SCALE TOKYO VS CAR-SCALE US CITIES
Fig9 & 10 show the stark differences in urban tissue patters of Tokyo and US cities.
Tokyo pattern is consisting of narrow but intensive road net work and small size blocks
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and land parcels. US pattern is made of wide but scarce road network and large size
blocks and land parcels. These patterns respectively lead to human scale walk-able
Tokyo and car scale non-walk-able US cities.
Fig9: (left)
Spatial Configuration Differences
between American style Urban
Formation & Japanese style one
Fig10: (below)
AMERICAN STYLE
JAPAN STYLE
Characteristic Differences between
URBAN FORMATION
URBAN FORMATION
American Style Urban Formation &
Japanese style one
American style urban formation
Japan style urban formation
Wide but fewer Roads
Narrow but longer Roads
Larger Lots & Buildings
Smaller Lots & Buildings
L
P
Suited for Motor Vehicle Access
Grand Scale
Rough Composition
Non – walkable
Not suited for Automobile Access
Human scale
Subtle Composition
Walkable
This Tokyo urban tissue formation creates the landscape shown in Fig11, of which
main characteristic is the aggregation of small sized buildings and land utilization. In
Tokyo respective land parcels are divided into small sized land plots covered with
respective small sized individual buildings. This is based on human scale walk-able
road network systems and has resulted in a very fair distribution of land resources to
individual citizens. This type of land resource subdivision and distribution could in turn
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enable respective land and building owners to invest on their own in individual,
incremental and timely manners and this prevents Tokyo districts to be blighted
simultaneously and in wide areas. As land parcels subdivided into small size, distributed
among numerous owners and as individual building investment supported by building
industries, Tokyo could be a sustainable city.
Fig11: Bird’s Eye View of
a Tokyo’s Typical Low-rise
Residential District
Large scale developments
Small scale developments
Fewer owners
Numerous owners
Investments beyond ind’ls’ capacity Investments within ind’ls’ capacity
Hard to maintain / renovate
Easy to maintain / renovate
Fig12: Characteristics of Tokyo’s Typical Subdivision Pattern
NARROW ROADS CHARACTERIZE TOKYO
As for commercial areas shown in Fig 13 & 14, smallness of shop sizes and multitude
of shop numbers enable to create human and livable townscape and to attract many
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shoppers and eaters.
Fig:13: TOKYO BACKSTREET’S LIVLINESS
Fig14: TOKYO ALLEY’S OPEN CAFE
Narrow roads in residential areas as shown in Fig15 entail serene living environment
free from motor vehicle related annoyances as traffic accidents, air pollution and so
forth, while keeping the convenience brought by car utilization. Residents choose small
cars accordingly and spaces for greens are secured by minimizing car parking spaces.
Fig15: TOKYO RESIDENTIAL AREA’S NARROW
STREET & COMPACT SIZE CAR
Fig 16: PONTO-CHO’S NARROW ALLEY IN KYOTO
This sort of townscape is not a modern made one but is rooted in Japan’s traditional
townscape such as historical townscape in Kyoto as shown in Fig16 above.
INCREMENTAL LAND-USE CHANGES IN TOKYO
Fig17 & 18 below show a traditional low-rise wooden tenement house in Tokyo and its
ground level corner room being converted to a small shop space. In these figures two
typical manners of Tokyo’s urbanization mechanism are illustrated. These are small
scale and incremental process. In this case, one compartment of existing apartment
building is converted into shop space. With doing like this way, Tokyo’s economical
viability could be maintained.
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Fig18:
Same Building’s
Night VIew
Fig17: SMALL SCALE CONVERSION FROM
RESIDENTIAL TO COMMERCIAL
FALL OF LOW-DENSITY (NON-COMPACT) NEW-TOWNS
Once Japan’s city planners tried to mutate Japan style urban formation to Western style
modern and motor vehicle based formation. Their plans had been realized in so-called
new-towns located mainly in urban fringe hilly areas. Wide roads networks, large scale
parks, large size building plots had been installed and planners expected Western style
new-towns’ victory over Japan’s indigenous urban forms comprising of narrow roads
and small and high-density building plots. Fig19 through 22 below show the different
formations of each system. However the victory was given to the indigenous system
and new-towns are now at the blink of deppretion.
住宅密度比較（初台）
Fig19: TOKYO’
TOKYO’S HIGH BUILDING DENSITY AREAS
IN SHINJUKU
Fig20: BIRD’S VIEW of HIGH DENSITY AREAS IN
SHINJUKU
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住宅密度比較（向陽台）
Fig 22: BIRD’S EYE VIEW OF TOKYO’S LARGEST
TAMA NEWTOWN
Fig21: LOW DENSITY AREAS in TAMA NEWTOWN
COMPACT HOMES COULD BE LIVABLE AND PLEASANT?
It is understandable that people would concern about narrowness of their living spaces.
However, it could be contended as well that spaciousness would not necessarily be a
cursor of livability and satisfaction.
Fig23 shows a comparison of typical single family house plans of Japan and US. US
house size is two times as ample. Still Japanese people are satisfied with Japan standard
smaller compact houses. This fact tells us space size could be minimized without
lowering living standard and satisfaction.
A Single Family Home
in Japan
on 150㎡ land parcel
A Single Family Home in
US on 400㎡ land parcel
Fig23: Size Comparison of Typical Japanese & US Single Family Homes
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T. AZUMA’S TOWER HOUSE & TADAO ANDO’S SUMIYOSHI ROW HOUSE
Two very small houses shown in Fig24 & 25 are well known worldwide and have been
selected for “100 most prominent 20th century architecture of Japan. Tower House land
plot size is just 20m2 and for Sumiyoshi Row house that is less than 50m2.
FIg25:Tadao ANDO’s
Sumiyoshi House on a
46.20㎡ Lot (below)
Fig24:Takamitsu Azuma’s
Tower House on a
20.56㎡ Lot (above)
NORIO UMEZAWA’S ATELIER –UCompact house in Fig26 & 27 was designed by Norio Umezawa as his own retirement
house for living with his wife. Land plot size is 100 m2 and floor area is only 55m2.
House plan is consisted of ground level living/dining room and up stair bedroom/den.
This compact floor area is more than enough for an aged couple. By containing building
coverage ratio down to 33%, he managed to create front and back gardens even in a
100m2 land parcel. With these two small gardens, Umezawas could command a very
pleasant garden views through wide openings.
FIg26:
Norio UMEZAWA’s
ATELIER U
Lot size:115㎡
Covered:38㎡
BCR:33%
Floor area:55㎡
Fig27
Fig27:: FRONT VIEW OF ATELIER U
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ANALOGY OF COMPACT CARS
In the sphere of passenger cars, compact cars are gaining ground and increasing market
share. There are multiple reasons for this trend. In Japan’s context, it could be explained
as follows.
Analogy of Compact Cars
125 million population vs. 80 mil cars
1 car for 1.5 people
Compact Cars are suited for one-person occupied car
+ merits: low prices, low tax-rates, high fuel efficiency,
low gas consumption, low CO2 emissions
Compact but Acceptable
Fig28:
Analysis of Market Success of Compact Cars in Japan
Homes as well could be compact, if thinking as follows.
How about Homes?
Shrinking Household size
Singles and Small size families Share Increasing
Compact Homes are suited for small size families
low prices / rents
Enabling to move up to more convenient areas
Leading to Compact Cities formation
Reduction in Material and Energy Consumption
Leading to Sustainable World
Compact but Acceptable
Fig29: Analogy of Compact Cars to Compact Homes
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HOW TO MAKE TOKYO SUPER-LOW-CARBON; UTILIZATION OF
NATURAL ENVIRONMENTAL THERMAL ENERGY POTENTIAL
Tokyo is a very energy efficient city a caused of its dense and human scale urban
formation and its extensive commuter train rail-way networks. So as to make Tokyo
more energy efficient and make it one of the World’s top energy efficient cities, the very
key idea is the recognition and utilization of Natural Environmental Thermal Energy
Potential.
Cities seem to be completely artificial territories. This image is not correct. Cities are
just submerged in natural environmental systems. Cities could not been livable
without sunlight, solar heat, air & atmosphere, wind flow, water flow, evaporation &
precipitation, soil and bedrocks. Without these grants of the nature, we could not survive
even just a second. Natural systems are consisted of four elements; sun, air, water and
soil. We should combine our urban systems and natural systems into mutually beneficial
compound. This combination could be attained via two approaches; one is a passive/
ecological approach and the other is an active/ technological approach.
Matrix in Fig30 shows the relationship of these elements and list up energy savings
measures and CO2 emissions reduction measures relevant to urban living.
As for the active /technological approach, there is a tendency that only PV and Wind
Turbine are saviors but the most powerful actors are thermal energy potential stored in
air, water and soil, which could be collected and utilized with Electric Heat Pumps. In
this sense, natural environment thermal energy potential + EHP are the main actors to
reduce CO2 emissions. Among technological measures, most substantial one is EHP.
We should
seeto
ourIntegrate
cities & buildings
as being
dependent
on and and Technological
Fig30:
Needs
Ecological
(Passive)
Approach
integrated with natural energy systems. Otherwise we could not
(Active)
Approach societies.
attain low-carbon
4 Natural
Energy
Sources
Solar
Ecological Approach
Passive Solar
Solar Heat Collection
Atmosphere
Wind Path
Outdoor-air
Cooling
Soil/Bedrock
& Vegetation
Green Shading
Evaporation
Water Bodies
& Flows
Technological Approach
Excessive Heat
Mitigation
PV Cell
Cities &
Buildings
Air-thermal EHP
Wind Turbine
Geothermal EHP
Water-Thermal EHP
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TOKYO AS A WATER-THERMAL ENERGY RICH CITY
Central Tokyo districts are facing on
Tokyo bay and several rivers pouring into it.
This geographical setting enables Tokyo to
rely on water thermal energy potential as
energy sources for Air-conditioning and
Water Heating.
Fig31:
Central TOKYO & Its Water Systems
MULTI-FUNCTION OF WATER SYSTEMS
Water system is a comprehensive one consisting of various subsystems. Natural
subsystems are sea, river, lake, underground water flow, precipitation and so forth,
artificial subsystems include water supply, sewerage, canal, waterways and so forth.
Water bodies and flows have many functions as well. By providing for water to all
living creatures, it sustains whole ecosystem. By discharging floodwater, it prevents
disasters. By punctuating land shapes, it defines urban landscape. By its own thermal
mass and evaporation, it mitigates excessive heat conditions as heat island phenomenon.
It could serve as transportation routes as well. Besides these functions, we are seeing a
substantive possibility of water as a source of thermal energy potentials. It is huge
storage of thermal energy and its water flow itself serves as thermal energy conduit.
Composition & Functions of
Water Systems
□Natural Systems
Sea
Rivers
Underground water flows
□Man-made Systems
Water ways
Sewerage
Sustaining Ecological Systems
Fig32:
Mitigating Excessive Heat
Conditions
Composition &
Providing Thermal Energy
Potentials
Serves as Energy Conduit
Systems
Functions of Water
Drainage & Flood Control
+ Emergency water supply
+ Emergency Transportation
routes
Serves as Transportation Route
Shaping Landscapes
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SUPER-LOW-CARBON STRATEGIES BASED ON WATER THERMAL
ENERGY + ELECTRIC HEAT PUMPS (EHP)
To further energy efficiency and CO2 emissions reduction, it is vital for Tokyo areas to
enhance utilization of water stored thermal energy potentials. The way to implement this
strategy is two fold.
First step is transforming thermal production method from fossil fuel burning systems
to non-fuel burning systems, of which center piece is the adoption of EHP system.
Second step is enhancing EHP property by providing water stored thermal energy
through various paths like as sewerage networks, rivers and water-ways networks and
so forth.
How to integrate man-made & natural systems
Fig33:
Man-made Systems
Means to Integrate Man-made &
Passive
Solar
Devices
+
Natural Systems
PV
Wind
Turbine
Solar
Energy
Wind
Energy
Electric
Heat-Pump
Natural Systems
Thermal Energy Potential
stored in Atmosphere ,
Water and Soil
POTENTIAL AND AVAILABILITY OF WATER THERMAL ENERGY
Tokyo has the ample capacity of Water borne thermal energy potential. As for Tokyo
central districts’ (Chiyoda, Chuo and Minato wards) large scale offices of which floor
areas are more than 10000m2, 100% of energy needed for heating and water heating
could be covered with thermal energy stored in rivers, sea and sewerage system. As to
cooling demand, more than 80% of energy could be covered with water borne thermal
energy as shown in Fig34.
Fig34:
Potential & Availability
of Water Contained
Thermal Energy in
Midtown TOKYO
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