emergy

THE SHAPE OF EMBODIED ENERGY

The sustainable cities of the future will take on forms of necessity,

deliberate to the process of conserving energy, apparent to the

means through which it produces energy. Transport will be kept

local. Food growth will be kept local. Building materials will come

from regional resources. In fact, a new regionalism will be born out

of these forms of necessity. Energy generation is likely to

complement local climate and renewable resources available.

Developed nations around the world are now commiting to reducing

energy consumption. The United States is aiming for a 15%

reduction in energy consumption by 2015, down to 50% of todays

consumption rate in 2030. However, these goals only confront the

problem that operating energy poses, on a static energy grid.

What these numbers fail to acknowledge is the role embodied

energy plays. This is the energy spent extracting, processing,

current operating energy

ygrene deidobme detcejorpygrene deidobme tnerruc

projected operating energy

Operating Energy vs. Embodied Energy(year vs. % of 2010 operating costs)

100

90

80

70

60

50

40

30

20

10

02010 2015 2020 2025 2030 2035 2040 2045 2050

15%

reduc

tion g

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50%

reduc

tion g

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manufacturing, and transporting materials and components.

Without changes in transit habits and resource management,

increasing consumption will drive energy costs higher despite more

efficient operational energy. Embodied energy effects our

environment at different scales. Examples that follow provide data

for mounting concerns facing the region, the metro area, the city, the

district, down to the individual building level.

The current shape of our cities costs too much. The systems in

place are unsustainable. These efforts will be put to a halt by some

means, voluntary or unvoluntary, at some point in the future. In the

conclusion of this section, you will find architectural solutions of the

voluntary kind, to be implemented before the costs are too great.

Operating Energy of Light Duty Vehicles(year vs. % of new vehicles manufactured)

2010 2015 2020 2025 2030 2035 2040 2045 20502005Wor

ldw

ide

Ligh

t Dut

y Ve

hicl

e S

ales

(mill

ions

)

20

40

60

80

100

120

140

160

180

conventional gasolinehybrid gasolineplug-in hybrid gasoline

conventional diesel

diesel hybrid

plug-in diesel hybrid

H2 hybrid fuel cells

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URBAN ENERGY SYSTEMS

RESOURCES

Coal- Finite Coal Energy represents the largest

component of the US Grid. However, it is

not present in the Northeast, and the

nearest extraction sites are too far away to

be considered viable for the region.

Biomass- Replacable Biomass Energy is in plentiful supply in the

Northeast and is a regenerative fuel

source. Some areas of Maine could

produce as much as 9850 GJ of energy a

year relatively local to point of use.

Solar- Infinite Solar Energy is everpresent. In the

Northeast it is not as strong and realiable

as in other regions, however, generating

only 1500-1600 kWh/yr per sqaure meter

of photovoltaic panel.

The embodied energy of energy resources is most efficient when the

proximity is close, and the extraction costs are low. Not only the

transportation to point of use, but transmission over the grid reduces

efficiency in the energy we consume.

In the Northeast, many energy resources are available, but not all

are efficient in implementation. By analizing our resource efficiency,

we can make better choices about powering cities in the future.

Energy generation will take the shape of regional resources.

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Wind- Ininite Wind Energy is an abundant natural

resource in the Northeast, specifically at

the coasts, where many of the existing

metropolitan areas are situated. This

makes it ideal for implementation.

Petroleum- Finite Oil Energy is similar to coal in that it takes

much energy to extract, and the supply is

not close to the Northeast. In fact, over

half of our oil energy comes from the

Middle East, much too far to be viable.

Hydroelectric- Replacable Hydroelectric Energy has been explored

extensively to spotty results in the

Northeast. There are still oppurtunities for

this renewable resource; as of now it

provides only 6.9% to the energy grid.

50% imports

petroleum

biomass

solar

wind

hydroelectric

coal

0 100 200 300 400

Average Distance Traveled by Energy Source (miles to point of use in northeast)

500 600

5800

URBAN ENERGY SYSTEMS

Philadelphia

Washington D.C.

NORTHEAST MEGALOPOLIS

BTU/miletime (min.)

distance (mi.)BTUs

4983251219

1091277

326175

185603285

1608237213

342504

749251219

164031

1801315230

41400

4983165136

677688

326142

125407265

1608100120

192960

749165136

101864

180944162

29160

BTU/miletime (min.)

distance (mi.)Total BTUs

498312097

483351

32615795

71155

16086597

155976

74912094

275514

180667120

21600

BTU/miletime (min.)

distance (mi.)Total BTUs

BOSNYC

NYCPHL

PHLD.C.

Boston

New York

The Boston to Washington network,

informally called Bowash, describes the

densely settled northeastern seaboard of

the mainland United States, currently

comprised of four focal cities: Boston, New

York, Philadelphia, and Washington D.C.

Representing an extraordinary concentra-

tion of individuals that collectively assert

great influence on the nation's economic

and historical identity. All four cities form a

megalopolis t h a t i s home to nearly

50 million

people - 17% of the country's

population on less than 2% of its land area.

Although each city functions as a distinct

entity, the high population density and

continuously sprawling extent of develop-

ment in the region has resulted in a vast

system of energy intensive transit corridors

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PEAK OIL

1970mill

ion

barr

els/

day

1980

1990

2000

2008

0

25

50

75

100

thou

sand

bar

rels

/day

1980

1990

2000

2008

1200

900

600

300

0

thou

sand

bar

rels

/day

300

200

100

0 1980

1990

2000

2008

80

60

40

20

0

1980

1990

2000

2009

United States

Global

Petroleum Production

mill

ion

barr

els/

day

BurganKuwait

SamotlrSiberia

PrudhoeAlaska

CantarellMexico

KashaganKazakhstan

1930

1940

1950

1960

1970

1980

1990

2000

2010

2020

2030

2040

2050

0

10

20

30

40

50

60

billi

on b

arre

ls/y

ear

production

Source: U.S. Dept.of Energy, March 2010

Source: U.S. Dept.of Energy - Energy Information Agency

Source: EPA Report - GHG Emissions from U.S.Transportation Sector

GhawarSaudi Arabia

major discoveries

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Peak oil describes the point

when the maximum rate of

global petroleum extraction has

been reached, resulting in a

terminal decline in production.

The implications for this exhaus-

tion of fossil fuel resources will

reverberate on every level of the

world economy and significantly

alter human consumption and

While our nation does consume

a majority of the worlds oil,

China and India are putting

millions of new cars on the road

each year as the ranks of their

community development.

In the immediate future, production of this finite resource will continue increasing to keep

up with demand, but the unavoidable truth for the long term is that we have reached a

point when oil can no longer be relied upon as the default source of energy

middle classes steadily grow.

URBAN ENERGY SYSTEMS

Newburyport

Plymouth

Boston

GREATER BOSTON

BTU/miletime (min.)

distance (mi.)Total BTUs

498350

38.7192842

326150

38.728986

16089835

56280

180252

45.68208

BTU/miletime (min.)

distance (mi.)Total BTUs

498343

40.3200814

326143

40.3131418

16088336

57888

180246

44.37974

NewtonNatick

FraminghamWestborough

WorcesterAuburnSturbridge

Palmer

Springfield

Ludlow

0 1

2

3

4 5

6

7

8 9

10

11

20031994

Mas

s. T

urnp

ike

Traf

fic R

ates

(mill

ions

)

The Boston metropolitan zone extends beyond the borders of Massa-

chusetts to include neighboring New Hampshire and Rhode Island. The

area is primarily traveled over several major interstates: I-93 and I-95

running north-south, I-90 running east-west, and I-495 which loops

through the citys immediate suburbs. The figures at right show the

varied energy intensities when traveling inbound from two coastal towns.

The Massachusetts Turnpike is a relic of mid-20th century infrasructure,

originally part of the Interstate Defense Highways Act of 1956. The

rates above reflect traffic patterns before and after Bostons notorious

Big Dig, which extended the Turnpike (I-90) eastward under Boston

Harbor and to Logan International Airport.

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TRANSIT TRENDS

50

75

100

125

150

1980

1990

2000

2009

mill

ions

0

U.S. Sales

1975

1985

1995

2005

-

Commuter Rail Energy Intensity

5

4

3

2

1

0BTU

out

put (

billi

ons)

passenger miles (hundred thousand)

1980

1990

2000

2008

1985

1995

2005

Middleborough/Lakeville

HaverhillFitchburg

LowellRockport

South Station

Forge Park-495

Stoughton

Providence

Worcester

North Station

Newburyport

Greenbush

KingstonPlymouth

I-495

I-95

I-93

I-90

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% s

crap

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Vehicle Longevity

4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

age (years)

0

5

1

0

15

20

2

5

30

1980 M.Y.1990 M.Y.

1970 M.Y.

The proliferation of auto-oriented

developments characterized

settlement patterns in the

perimeter communities built

around Boston throughout the

20th century, reflecting national

trends that were explicitly encour-

aged by the national government.

MBTA commuter rail service is provided along 13 active trunklines, essentially

split into two districts, North and South for a total of 394 route miles. The Massa

chusetts Bay Commuter Rail Co. operates and maintains the network and trains,

acting as a third party contractor to the MBTA. As of 2009, the company operated

with 80 passenger locomotives, 410 active coaches, and 127 stations.

A map of the MBTA commuter

rail system reveals its limited

abilities to link outbound destina-

tions, a task that is taken up by

the highways that loops through

Bostons focal perimeter commu-

nities. A rapid transit ring that

follows a similar path would allow

for rapid public transit between

points further outside city limits.

URBAN ENERGY SYSTEMS

EMBODIED ENERGYCITY HALL

-

.

brick8.4 MJ/brick.62 Kg/CO2/brick

concrete.95 MJ/Kg.13 Kg/CO2/Kg

903,827 ft. concrete =3

2.5 million bricks =55.8 million MJ / 7.6 million Kg CO221.5 million MJ / 1.6 million Kg CO2

There is almost certain consensus from the

scientific community that human sourced

emissions are causing the warming of the planet.

Coupled with the impendingly widespread

knowledge that petroleum and other fossil fuels

are near points of exhaustion, there has been a

surge in research and development to improve

the operational efficiency of the many machines

that make our modern lives possible: vehicles,

utility power, building mechanical systems, etc.

As opposed to direct energy input and green

house gas ouput, embodied energy measures

the energy input of a product throughout its

lifecycle, from extraction of raw materials,

through processing and delivery, and finally onto

recycling or disposal. It is a useful measure of

determining the energy consumption and total

environmental impact of particular materials

used widely in industry. These totals are

expressed in terms of megajoules of energy

input and kilograms of carbon dioxide emissions

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THE COST OFREPLACEMENT

steel36.8 MJ/Kg

2.78 Kg/CO2/Kg

glass15 MJ/Kg

.85 Kg/CO2/Kg

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2,115,102 Kg steel (structural + sheet) = 77.8 million MJ / 5.8 million Kg CO2148,324 Kg glass = 2.2 million MJ / 126,000 Kg CO2

In less than fifty years of operation, City Hall

has weathered derision from both public and

political spheres. Local developers have come

forth with concepts for rebuilding the area as a

mixed use district with new commercial and

office space. These proposals often feature

renderings of sleek steel and glass office

blocks, standing in sharp contrast to the plaza's

current composition of brick and concrete.

The environmental impacts resulting from such

a major project would be staggering. The

demolition and removal of millions of cubic feet

of concrete would release substantial volumes

of C02, N02, and particulate matter into the air.

The construction of new buildings would

require enormous investments of embodied

energy, considering that production of a Kg of

steel consumes 38 times more megajoules of

energy than a Kg of concrete. Considering

these energy impacts, the preservation of City

hall in its current form is imperative.

URBAN ENERGY SYSTEMS

BUILDING LIFE

The embodied energy of building is not static. In fact, the embodied

energy of a building is always increasing due to repairs and

refurbishment. Most commercial real estate goes through numerous

refits resulting in a considerable increase to embodied energy costs.

This example looks at the embodied energy of the recurring type, in

a generic commercial building at initial completion, 25 years into its

50 years, and 100 years. The number of refurbishments add up over

the years, creating embodied energy costs that nearly catch up to

operating costs.

Recycling can play a role in reducing these numbers, by avoiding

demolition and additional extraction energies. Ultimately, reducing

the amount of refits is the only path to efficiency.

Embodied Energy extraction of materials manufacturing components transport to site construction processes

replacement of materials replacement of components

extraction of materials manufacturing components transport to site

demolition process transport

Operational Energy

heating load cooling load lighting equipment

refurbishment processes

construction use refurbishment demolition

BUILDING LIFE

RECYCLING PROCESSES

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Recurring embodied energy plays a crucial role in the actual energy

cost of a building. The services and finishes are especially

significant. Special attention must be paid to materials longevity

and ability to replace parts rather than whole assemblies.

With embodied energy, every move generates some quantity of cost.

Even in adaptive reuse strategies, the best practices only minimize

the impact to our environment. Acknowledging that impact leads to

better, delibrate choices. Durability is at the core of building life.

Operating Energy vs. Recurring Embodied Energy (years)

fixed operational energy

recurring embodied energy

initial embodied energyinitial construction

0 25 50 75 100 125

Time Frame 25 Years 50 Years 100 Years GJ % increase GJ % increase GJ % increase Site Work 65 5.2 357 28.6 0 0Structure 0 0 0 0 0 0Envelope 3873 65.3 8943 150.7 20060 338Finishes 3869 133.4 9339 322 21046 725.7Services 3369 64 9920 188.5 23093 438.8Construction 671 48.9 1714 124.8 3911 284.9Total 11848 56.5 30272 144.3 68110 324.6GJ/m2 2.56 6.55 14.74

Yohanis & Norton, 1999

URBAN ENERGY SYSTEMS

STRUCTURE

The structural material selected makes an impact on how much

embodied energy a building is comprised of initially. In this example

by Cole & Kermnan, a generic commercial building is constructed

using three different material methods: wood, steel, and concrete.

The size and shape of the building is kept constant to determine

which method is best at conserving embodied energy.

As a second variable, the experiment considers the impact of

including an underground parking structure (comprised of concrete),

to calculate that energy cost as well.

To the right is the standard floor plan of the building. It is 3 stories

high and 4620 m2 in total area (50,000 ft2). All core components are

included: bathrooms, stairs, and elevators. Below it are building

sections showing the building with and without underground

parking.

The table on the next page shows the embodied energy required to

produce the structure, broken down by category and percentage of

total cost.

Finally, an amount of energy per unit area is given, demonstrating a

clear choice for structural material in quantitative terms.

Floor Plan of Generic Commercial Building

Building Section (with no parking structure)

Building Section (with parking structure)

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Structural Material Wood Steel Concrete GJ % GJ % GJ % With Underground Parking Site Work 1246 5.9 1246 5.3 1246 5.6 Structure 4268 20.3 6836 28.9 5398 24.4 Envelope 5935 28.3 5964 25.2 5822 26.3 Finishes 2900 13.8 2825 11.9 2945 13.3 Services 5263 25.1 5263 22.2 5263 23.8 Construction 1373 6.5 1549 6.5 1447 6.5 Total 20984 100 23683 100 22121 100 GJ/m2 4.54 5.13 4.79 Without Underground Parking Site Work 1344 6.8 1344 6 1344 6.4 Structure 3088 15.7 5650 25.2 4303 20.6 Envelope 5935 30.1 6062 27 5822 27.9 Finishes 2935 14.9 2799 2.5 2920 14 Services 5110 25.9 5110 22.8 5110 24.5 Construction 1289 6.5 1468 6.5 1365 6.5 Total 19699 100 22433 100 20863 100 GJ/m2 4.26 4.86 4.52

Cole & Kernan, 1996

Steel and concrete cost 2734 and 1164 GJ more than wood

construction, respectively. Steel is only well-applied to dense

development. Concrete requires too much material. For this building

shape, wood structure is the most energy efficient.

Notice the increase due to the addition of underground parking.

With parking on site, people will be more likely to drive in. Leaving

out the parking garage will encourage other transit solutions would

therefore have a two-fold benefit on the energy cost.

URBAN ENERGY SYSTEMS

MATERIALS

Some materials require more embodied energy to extract and

process than others. Metals and plastics are the greatest offenders,

whereas wood, masonry, plaster, and concrete appear to be minimal

in their impact, costing the least to produce. However, because

some materials appear more often, the refinement of those

processes should receive critical attention.

When applied to the percentage of use in total buildings, concrete

takes up a majority share of the materials in use. Therefore, the total

embodied energy of concrete costs more than any other material

due to its prevalence in construction. Much benefit could come from

reducing energy costs in the concrete creating process (as well as in

steel and plastics), when it comes to building.

steel aluminum copper wood plastic concrete masonry glass plaster ceramics 0

50

100

150

200

Em

bodi

ed E

nerg

y in

Mat

eria

ls (G

J/ to

nne)

Em

bodi

ed E

nerg

y in

Bui

ldin

gs (G

J)

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Ytechnical ceramics

When materials are evaluated for their structrural capacity, durability

comes into question once again. Below is a chart of various

materials sorted by relative stiffness (as determined by Michael

Ashby). Note that the embodied energy required is exponential,

thus making material ranges on the left side of the chart far less

intensive than those on the right.

When charted by their relative strength, the materials stay grouped

in fairly similar ranges. The lesson is not to completely avoid metals

and plastics, but to selectively implement those materials when

necessary to perform tasks requiring high durability or high strength.

Material selection is a function of performance requirements, to be

minimized where possible.

conrete/brick

woods

foams

metals

polymers /plastics

elastomers

composites

technical ceramics

Embodied Energy per cubic meter (MJ/m3)

Youn

gs

Mod

ulus

, E (G

Pa)

102 103 104 105 106 107 0.01

0.1

1

10

102

103

conrete/brick

woods

foams

metals

elastomers polymers /plastics

composites

Embodied Energy per cubic meter (MJ/m3)

Stre

ngth

, (M

Pa)

102 103 104 105 106 107 0.01

0.1

1

10

102

103

104

URBAN ENERGY SYSTEMS

LESSONS

Energy generation must come from local sources to be efficient. Currently,

energy from the electric grid is comprised of too few renewable resources,

from too far away. The northeast region has other options, the closest and

most plentiful being wind and biomass.

Public transit options need to be multiplied at a regional scale. The predomi-

nance of private vehicle travel can be mitigated by investment in high speed

rail infrastructure between major urban centers. Designing railroad networks

to be more time and cost effective than driving will ultimately reduce vehicle

miles travelled.

New residential developments should be planned near public transit.

Proximity to transportation corridors will give residents greater incentive to

use shared transit methods for getting around their communities. Greater

Boston in particular needs a perimeter loop to link its commuter rail termini.

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Existing architecture must be emphasized over new construction. Considering .

the energy consumption of a building over its entire lifecycle, durability and

flexibility will be realized as the true indicators of sustainable design. Outright

demolition and replacement has been proven as an inefficient building model.

Cities should be developed for density. Currently, buildings are being erected

with expansive open spaces between. Planning in the future should aim to keep

these structures and fill the gaps inbetween, improving individual building energy consumption and transportation patterns

Building materials should be selected on a performance basis. Our current

thinking on how energy is consumed is incomplete. Buildings themselves take

energy to construct and refurbish, thus the strength and durability of building

materials should be selected deliberately per function, with as little replacement

as possible.