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The 310 m tall Pearl River Tower, in Guangzhou, China, is expected

to be the most energy efcient o all the worlds supertall struc-

tures, opposite.As designed, the project should come close to being

a net zero-energy building. Such buildings do not require the

city or region in which they are lo cated to generate any additional

energy on their behal. Photovoltaic cells will be integrated into th e

tower both as the buildings skinin the orm o spandrel panels

and as a source o power. To achieve the greatest productivity, the

cells will be located in an asymmetrical arrangement at the roo

level, where the system will not only provide electricity but also

unction as a solar shade or the section o the building that will be

most susceptible to the negative eects o direct solar radiation.

The Pearl River Tower, inGuangzhou, China, has been

designed to be the most energyefcient o all the worlds supertall

structures. Although the designteams original goal o constructinga net zero-energy building thatwould sell its excess power to the

local electrical grid is unlikely to be

achieved, the structure is expectedto consume nearly 60 percentless energy than a traditional

building o similar size and couldserve as a model or uturecarbon-neutral towers.

By RogeR e . FR ec hette I I I , p.e .,

leed ap , an d Russell g I lc hR I st

The industrialization o the world has led to

great innovation, great technological advances,

and powerul national economies. It has also

resulted in an incredible appetite or energy, most

notably energy generated through the use o os-sil uels. This massive consumption o ossil uels

has sharply increased the levels o carbon dioxide

(CO2) in our atmosphere, resulting in a steady

but rapid warming o the planet. The ramications o this

man-made environmental shit are not yet ully under-

stood, but many scientists believe the results could be

catastrophic.

Many actors have contributed to this crisis. But while

Seeking

Zeroenergy

AllimagesSkidmore,Owings&MerrillLLP,2007.Allrightsreserved.

38 Civil Engineering January 2009

0885-7024-/09-0001-0038/$25.00 per article

2008 American Society o Civil Engineers 2008 American Society o Civil Engineers

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transportation and industrial activity have long

been recognized as major sources o CO2 emis-

sions, the emissions associated with the built

environment may actually be the single greatest

contributor to global warming. Thereore, when

architects and engineers design buildings, it will

become increasingly imperative that they work

to reduce the amount o energy consumed during

the construction phase as well as limit the CO2

emissions that are generated by their buildings

once they are in use.

Designed by Skidmore, Owings & Merrill llp(som), o Chicago,

the 310 m tall Pearl River Tower, in Guangzhou, China, is scheduled

or completion in 2010 and is expected to be the most energy e-

cient o all the worlds supertall structures. As designed, the project

should come as close as possible to a net zero-energy building. Such

a building does not require the city or region in which it is located

to generate any additional energy on its behal and thus is environ-

mentally benign. With such buildings, the city or reg ion can keep its

power generation stable or possibly even decrease it. In this way the

city or region can expand, increase its density, and prosper without

the need to consume additional ossil uels, thus avoiding the potential

increases in harmul greenhouse gases.

The Chinese government recently set the goal o reducing the

nations carbon emissions by 10 percent by the year 2010. Because

the city o Guangzhou experiences some o the

worst air pollution on the planet, the city and

its province, Guangdong, are a major ocus o

this environmental initiative. The Pearl R iver

Tower project, which eatures both active and

passive approaches to limiting carbon emissions

through new technologies as well as reduction

strategies, could play an important role in devel-

oping a new model that will both provide higher

living standards and achieve important environ-

mental goals.

sombecame involved in the Pearl River Tower project in 2005

when it was hired by the China National Tobacco Company to

design a headquarte rs building or the Guangdong Tobacco Com-

pany, one o the largest companies in Guangzhou. The design brie

envisioned a high-perormance tower that would consume sig-

nicantly less energy than is typically needed by a building o this

size and type. The design team interpreted high-perormance

to mean a structure whose energy-saving systems and strategies

would work together in an integrated ashion to consume nearly

60 percent less energy than does a more traditional building.

The result was soms design or the 71-story Pearl River Tower,

which includes associated conerence acilities that increase the tota l

ootprint o the project to approximately 204,000 m. Although

the initial goal was to construct a building that would not require

the city or the reg ion to generate any additional energy on its

behal, modications to the original design arising rom economic

considerations and regulatory challenges made this goal unachiev-

able. But thanks to an all-inclusive design philosophy that wovetogether a variety o measures designed to reduce the buildings

dependency on the citys electrical grid, the Pearl River Tower is

expected to come as close as possible to that goal.

Such a high level o perormance requires a design team to con-

sider a host o issues, among them the site o the structure, the passive

and active energy sources available, the types o building materials

to be used, and the desi red indoor air quality. The team must also

determine ways o integrating these issues into the building design

in a substantive manner rather than including them in a way that is

purely or show. It is thus necessary to determine such basic elements

as site conditions, the buildings orientation, the local wind speed and

direction, and the path o the sun in the region and to draw on such

sophisticated approaches and technologies as radiant ceilings, double-

wall systems, photovoltaic devices, and wind turbines.

It was important to som that this holistic approach produce an

array o solutions that would be compelling at a conceptual level

and would survive the rigors o design development and uturevalue engineering exercises. This demanded a design approach

that looked not to orm but to perormance. In this way, superfu-

ous architectural detailing was avoided by ensuring that all o the

systems possessed a degree o interdependency.

The structure of this wide but narrow tower is based on a com-

posite system that utilizes both structural steel and reinforced-

concrete elements to resist gravity and lateral loads. The primary

lateral-load-resisting system features an interior reinforced-concrete

core and a series of composite megacolumns that are l inked by a

large, multistory system of structural steel X braces on the narrow

edge facades of the building. The perimeter columns are linked to

the reinforced-concrete core wall and the corner megacolumnsby a system of two-story outrigger and belt trusses at the major

mechanical levels. Engaging the perimeter columns with the out-

rigger trusses increases the effective moment mechanism of the

lateral system while the belt trusses work to equal ize the loads in

the perimeter columns. Structural steel moment frames also are

provided on the broad faces of the building for additional resistance.

Inherent redundancy and robustness are achieved with the addition

of the belt trusses and perimeter moment frames.

The thicknesses o the core walls range rom 700 to 1,500 mm

over the height o the building. The megacolumns cons ist o large

built-up structural steel I sections that are up to 900 mm deep by

700 mm wide; these I sections eature 100 mm thick plates sur-

rounded by reinorced-concrete encasements that are 3,000 by

2,700 mm or the bottom hal o the tower and 2,500 mm square

or the top hal. The structural steel X braces located between the

megacolumns also are ormed o built-up I shapes that typically

are 600 mm deep by 600 mm wide and have plates that are 50 to100 mm thick. Each system o X braces is roughly six stories tall.

The perimeter columns genera lly are built-up shapes below the

uppermost outrigger and are belt truss systems and rolled sections

above that point. The perimeter columns or the lowest third o

the tower consist o built-up I shapes 600 mm deep by 600 mm

wide with 100 mm thick plates; there are also 50 to 100 mm thick

cover plates on and between the fanges because o the loads rom

the lowest outrigger and belt truss sys tem. The middle third o the

January 2009 Civil Engineering 41

Four large openings approximately

6 by 6.8 m located at the mechani-

cal foors will unction as a type

o pressure relie valve or the

building, and vertical-axis wind

turbines installed in each open-

ing will harvest wind energy. The

buildings design will capitalize on

the pressure dierence between

the windward and leeward sides o

the structure, acilitating airfow

through the openings.

It was important to som that this holistic approachproduce an array o solutions that would be compelling ata conceptual level and would survive the rigors o design

development and uture value engineering exercises.

Cross Section of Air Temperaturesat Perimeter Zones


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tower consists primarily o built-up I shapes that are 600 mm deep

by 600 mm wide and have 50 to 75 mm thick plates. Below grade,

the perimeter columns are encased in concrete to simpliy the con-

struction interace with the basement levels, which are generally

concrete slabs reinorced in two directions.

The outrigger and belt truss elements also are built-up I shapes

ranging in depth rom 600 to 1,000 mm with widths up to

600 mm and plate thicknesses o 50 to 100 mm.

The typical foor raming takes the orm o rolled wide-fangebeams supporting a deck slab o concrete on metal with a total

thickness o 160 mm. The shear studs are welded to the beams

to provide composite action with the slabs. The maximum foor

beam spans are approximately 13 m.

The oundations or the tower take the orm o a 3,500 mm

thick reinorced-concrete mat extending under the core and

megarames as well as 4,000 mm thick reinorced-concrete spread

ootings under each o the perimeter columns. All oundations

bear on rock and extend approximately 28 m below grade level.

The initial goaldesigning an edice that would not require

the city or region to generate any energy on its behalwas

based on our concepts: reduction, absorption, reclamation, and

generation.

Reduction meant nding as many opportunities as possible to

reduce the amount o energy consumed. These reduction strategies

ocused on the expected largest consumers o energy within the build-

ingnamely, the heating, ventilation, and air-conditioning (hvac)

system and the lighting system. The reduction strategies incorporated

into the design o the Pearl River Tower included the ollowing:

An internally ventilated, high-per formance active double wallwith mechanized blinds on the northern and southern acades;

High-performance, triply glazed facades on the eastern and

western sides o the structure;

A so-called chilled radiant ceiling with a perimeter chilled-

beam system, both using chi lled water (approximately 14.5C)

delivered through a serpentine arrangement o copper piping that

is xed to the back o a curved metal shape or the ceiling system

and a series o metal ns or the perimeter beams;

A decoupled ventilation system providing only fresh air

that is cooled by the chi lled-water system described above and

delivered via a raised access foor;

A dehumidication system using heat collected from the

double-wall acade as an energy source;

A low-energy, high-efficiency

lighting system using radiant panel

geometry to assist in the distribution

o light.

Absorption, the second design concept,

made it necessary to ocus on strategies

designed to take advantage o the natu-

ral and passive energy sourcesnamely,

wind and solarthat will pass around,

over, and under the buildings envelope.

The absorption strategies used on the PearlRiver Tower included the ollowing:

A wide-scale photovoltaic system

integrated into the buildings external

solar shading system and glass outer

skin, which is located on the southern

acade;

The use of xed external shades

and integrated photovoltaic devices

on the eastern and western acades, as

well as integrated photovoltaic devices

within the western acade shades;

Maximizing the use of natural

lighting via controls that respond to

light and are integrated into a system o

automated blinds;

Vertical-axis wind turbines

designed to take ull advantage o the buildings geometry.The third conceptreclamationrelied on strategies to harvest

the energy that would already be resident within the building. Once

energy has been added to the building, it can be reused repeatedly. For

example, the Pearl River Tower is designed to use recirculated air to

help heat or cool the resh air rom the outdoors beore it is del ivered to

the occupied areas o the building. Naturally, this strategy is dependent

on the outside air conditions and requires absorption chillers.

Generation, the nal concept, envisioned the use o micro-

turbine technology to generate clean power in an ecient and

environmentally responsible manner. Indeed, the origina l plan was

based on the projected ability to generate enough electricity within

the structure to sell the excess to the local electr ical grid. Having the

ability to generate power more eciently than can be achieved by

the citys grid would result in a net reduction in greenhouse gases

associated with the buildings normal operation. For example,

a typical electric power utility grid is less than 30 to 35 percent

ecient by the time the energy has reached the building rom the

power plant source, according to Energy Eciency in the Power

Grid, a white paper produced by abb, Inc., o Zrich, Switzerland,

in 2007. By contrast, the on-site generation plant that was designed

or the Pearl River Tower was expected to generate power with

an eciency exceeding 80 percent. The original concept or the

building involved linking as many as 50 microturbineseach

approximately the size o a large kitchen rerigerator and powered

by such uels as kerosene, biogas, diesel, methane, propane, or natu-

ral gasto create a generating capacit y o 3 MW.

Unortunately, these plans were placed on indenite hold when the

Guangzhou utility decided that it would not connect the microtur-bines to the local electrical grid, which is oten unreliable. Because the

tower would not be able to sell its excess power to the utility, the cost

o the microturbine system could no longer be justied. Moreover, the

elimination o this technology meant that the goal o achieving a net

zero-energy building was unattainable. But the potential benets o

the microturbines were so compelling that the buildings basement has

been designed so that it can be retrotted to accommodate the devices

should the local utility ever change its stance.

The acade o the Pearl River Tower will eature an internally

ventilated double-wall system made up o doubly glazed, insulated

units integrated into 3.0 by 3.9 m unitized panels, as depicted in the

gure on page 47. Two hinged 1.5 by 2.8 m singly glazed leaves will

be xed to the back ace o the mullion to create an approximately

200 mm deep cavity with a small air gap at the base. Within the cav-

ity is a motorized silver venetian blind system in which the perorated

blinds measure 50 mm wide. The position o these blindsully

open, open at a 45 degree angle, or ully closedwill be controlled

by a photocell that tracks the movement o the sun and is connected to

the building management system. The exterior glazing will take the

orm o insulated, tempered glass with a low-emissivity coating; the

inner layer will be an operable clear glass panel that can be opened or

maintenance. The units will be suspended rom the top at each level

and laterally supported at the bottom.

This integrated acade assembly provides exceptional thermal

perormance as well as good visibility through the glass, and it should

allow or the enhanced use o natural lighting. In turn, this should

make it possible to reduce the amount o articial lighting required


Reduction meant nding as many opportunities aspossible to reduce the amount o energy consumed.

Wind Velocity Vectors at Mechanical Floors

Pearl River Tower IncidentSolar Stress Model


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in the space while preserving the excellent viewsvia the perora-

tionseven when the blinds are u lly closed. O greater importance,

the double-wall arrangement will be a vital component in maintain-

ing the balance between maximiz ing transparency and achieving a

high standard o comort or the buildings occupants.

As sunlight strikes the exterior doubly glazed skin, some o the

resulting solar heat gain will enter the cavity between the outer

and inner glazed layers. Fortunately, the cavity will act as a natural

chimney. The cooler air rom the occupied oce areas will enter the

cavity via a gap at foor level and act as a pressure relie valve to allow

more resh air to enter the occupied areas. The trapped air in the cav-

ity will then be ex tracted through the ceiling void to, depending on

the outside temperature, either preheat or precool the interior air.

By maintaining a low temperature on the interior layer o glassthe layer closest to the occupantsthe mean radiant temperature in

the oce space will be decreased. Thi s will then reduce the operative

temperature o the space rom, say, 27C at the perimeter to 23C

arther inside the oce, as depicted in the gure on page 41. This

lower operative temperature will create an environment o improved

thermal comort at the perimeter zones and should directly improve

the fexibility and usability o the areas closest to the exterior glazing.

A similar system is used on both the southern and northern acades,

in part or controlling glare but also because the northern acade is

exposed to solar gains rom the west in the late aternoon.

The Pearl River Tower, as mentioned above, will also eature a

decoupled radiant cooling ceiling that works in conjunction with

an under-foor ventilation air delivery system. This combination

should provide improved comort in all respects while simultane-

ously reducing the buildings energy demand and maintenance

costs. Furthermore, by requiring less material, it will also reduce

the structures capital costs.The oce space within the tower will encounter

heat gain daily rom a variety o sources. The people

in the oces, the ambient and work space light-

ing, the computers, and other oce equipment all

account or convective and radiated heat that must be cooled by the

hvac system. Heat gains at the perimeter of the building are much

more variable and usually di cult to control because o solar energy

transmission through the glazing. A water-based radiant cooling and

displacement ventilation system addresses each heat transer mode

with the appropriate cooling or ventilation system: r adiant loads are

controlled by the radiant system, and convective loads are controlled

by a combination o the radiant system and the displacement ventila-

tion system. This approach works better than a conventional orced

overhead mixing system, which is entirely convective, because water

is a ar more ecient transer medium than air.The system proposed or the Pearl River Tower

will also mean that signicantly less energy will be

required to power ans than in a standard variable

air volume system. With a conventional air volume

system, the warmer air, typically the

return air, can increase tempera-

tures within the building interior as

it migrates to return grilles located

throughout the loors. But the

decoupled system proposed or the

Pearl River Tower uses the exterior

double-wall enclosure as the return

air plenum. As the return air within

the perimeter zone is drawn to the

buildings exterior, the eect on the

interior zones is minimized.

The decoupled ventilation system

also enabled the design team to reduce

the buildings foor-to-foor height

rom 4.2 m to 3.9 mthe equiva-

lent o reducing construction by ve

stories. It also reduced the costs associ-

ated with the ex terior envelope and,

through the projected energy savings,

provided what may be the most envi-

ronmentally benecial aspect o the

Pearl River Tower design.

The system also enabled the design team to optimize the plan layout

by eliminating an rooms and reducing the size o air shats. This, in

turn, resulted in a reduced core area that increased the usable space on

each foor and thus increased the buildings revenue poten-

tial. Moreover, the decrease in an equipment provided thespace on the mechanical foors or the wind portals that

made the buildings wind turbine system possible, space

that would not have been available i a conventional

ventilation system had been used.

Wind looms large in the design o tall

buildings. It builds up positive pres-

sure on the windward side o the

structure andthrough vortex

shedding around the sides and

over the top o the build-

ingcreates large pockets

o negative pressure on the

leeward side. But i the air

is allowed to pass through

the building, the dier-

ential pressure rom ront

to back is reduced, as arethe orces on the building.

Moreover, such an approach

coners environmental bene-

ts structurally in that it reduces

the quantity o steel and concrete

that is required to maintain the

buildings stability.

The Pearl River Tower incorporates

our large openings approximately 6 by 6.8 m,

one on either side o the mechanical foors at

levels 24 and 48. These openings unction as a

type o pressure relie valve or the building and

also as a source o wind energy. Indeed, the acades o the structure

have been designed to decrease the drag orces and optimize the wind

velocity passing through these our openings. In particular, the broad

sides o the structure will be aligned perpendicular to the prevailing

winds, which or most o the year are rom the south, to create a

positive pressure on the windward side and a negative pressure on the

leeward side. By contrast, most buildings are typically a ligned so that

the narrower acades point toward the prevailing winds.

Given that the power potential rom wind speed is a cube unc-

tion o wind velocity, the wind power potential at the se our loca-

tions should be maximized. Thus, a small increase in velocity can

translate to a larger increase in potential power. Even a relatively

benign wind speed o 2 m/s should generate an energy output

approaching 8 m/s.

The Pearl River Tower will implement vertical-axis wind

turbines that are capable o harnessing winds rom both prevail-

ing wind directions with only a minor loss in eciency. The

buildings design capitalizes on the pressure dierence between

the windward and leeward sides o the building and

should acilitate airfow through the our openings. Onthe windward side, a stagnation condition causes the

locally increased pressure to be higher than the undis-

turbed pressure approaching the building. On the

leeward side, a low-pressure area is induced

by the high-velocity fow at the sides and

roo o the building.

The eect o the wind traveling

through the our openings was

careully studied in a wind tun-

nel testing rig that eatured a

scale model o the Pearl River

Tower. This testing took air-

fow measurements o the

wind speeds as the winds

approached the building

and also measured the cor-

responding air velocitieswithin the buildings our

openings. The model was

then rotated within the tunnel

to simulate what would happen

when the wind approached rom

all possible directions.

The results indicated that as the air

passes through the openings, the wind acceler-

ates and the velocity increases. I the wind strikes

the building at a perpendicular angle to an open-

ing, the velocity will drop. But rom almost every

other angle, the increase in wind velocity wil l

exceed the ambient wind speeds. In most cases, the velocity increases

should be more than twice the ambient wind speeds.

Thus, placing one vertical-axis wind turbine within each o the

our openings o the building will take advantage o the increased

power potential o the airstream. These wind turbines are low-vibra-

tion, low-noise units that operate within a wide range o wind direc-

tions and should provide power year-round. Thereore, the Pearl

River Tower not only should realize structure-related cost savings

as a result o adding the our openings but also should be able to avail

itsel o relatively ree energy by har vesting the accelerated winds that

will pass through these openings.

Like an increasing number o buildings worldwide, the Pearl

River Tower will integrate photovoltaic modules into the building

envelope rather than include such devices simply as an extra ea-

ture. The modules on the Pearl R iver Tower will serve both as the


The Pearl River Tower will implementvertical-axis wind turbines that are capable oharnessing winds rom both prevailing wind

directions with only a minor loss in eciency.

Comparison of Pearl River Towerwith Hypothetical Baseline Building:Projected Annual Energy Consumption

Projected EnergySavings from Large-

Scale SustainableDesign Strategies

Wind Tunnel

Test Data atWind Portals

PearlDesignBaseline

RadiantCooling

High-PerormanceGlazing

High-EfciencyEquipment

NoFlowFeatures

High-EfciencyLighting

DaylightResponsiveControls

High-EfciencyPlant

DemandBaseVent

HeatRecovery

IntegratedPV

WindTurbines

40,000,000

35,000,000

30,000,000

25,000,000

20,000,000

15,000,000

10,000,000

5,000,000

0

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buildings skinin the orm o spandrel panelsand as a source o

power. By avoiding conventional spandrel panels, the incremental

cost incurred in incorporat ing the photovoltaic modules should be

reduced and the lie-cycle cost improved.

Photovoltaic systems that are integrated into buildings otenhave lower overall costs than when they require separate, dedicated

mounting systems, according toBuilding Integrated Photovoltaics: A Case

Study, a report prepared in 1995 by Gregory Kiss,

Jennier Mahadev, and Raman Mahadev or the

U.S. Department o Energys National Renew-

able Energy Laboratory, in Golden, Colorado.

Careul study o the expected solar radia-

tion on the Pearl River Tower revealed that the

photovoltaic cells would be most productive

i they were installed in certa in locations on

the buildings envelope. As a result, the cells

have been located in an asymmetrical arrange-

ment at the roo level o the structure, where

the system not only provides electricity or the building but also

unctions as a solar shade or the section o the building th at is most

susceptible to the negative eects o direct solar radiation.

The cumulative benet o all the environmentally benecial

strategies included in the design o the Pearl River Tower willsignicantly reduce the amount o energy needed to operate the

building. The most notable reductions anticipated are associated

with the mechanical systems o the building, but

measurable savings should also be realized in the

cooling and lighting systems, as well as in the air

and water delivery systems.

The energy consumption o the building has

been modeled and compared with that o a hypo-

thetical baseline building that eatures the same

geometry but rather than utilizing similar envi-

ronmentally benecial measures relies instead on

the more established strategy o using air in place

o a water-based radiant ceiling system to cool the

building. As the gure on page 44 indicates, the

Pearl River Tower is expected to consume approxi-

mately 58 percent less energy on an annual basis

than the hypothetical baseline building.Ground was broken or the project in August

2006, and construction o the Pearl River Tower

proceeded through 2007 and 2008. The highest

portion o the structure should be erected during

the ourth quarter o 2009, and the building should

be completed by October 2010.

In developing the design or the Pearl River

Tower, the scope o the services that somprovided

included architecture, structural engineering, and

mechanical, electrical, and plumbing engineering

up through the detailed design phase o the project.

As required in China, som worked closely with a

local design institutein this case the Guangzhou

Design Instituteto ensure that all the necessary

local and statutory approvals were obtained with

respect to planning, zoning, and building codes.

Although many o the energy-saving strategies

and technologies in the design o the Pearl River

Tower were not new per se, their use in China has

been limited. This act, combined with the reluc-

tance o the Chinese authorities to import existing

technologies or manuactured goods rom other

parts o the world, meant that the perormance cri-

teria rom projects in the United States or Europe

were not easily transerred to this project. Further-

more, soms work was subject to peer reviews by

leading experts in China. While the requirement

or these reviews is understandable, such assessments tend to be based more

on theory than on practical experience. As a result, it was sometimes dicult

to convince other project team members o the v iability o the proposed solu-

tions. Moreover, eorts to address the concerns o the Chinese clients by using

examples rom projects in the West oten were not successul.

The design team has learned numerous lessons rom this project, including the

critical act that attempting to design and bui ld a tower that does not require the

city or region to generate any additional energy on its behal is a ormidable under-

taking, especially when the tower is supertall and is located in a city with a notori-

ously unreliable electrical grid. It is clear that the Pearl River Tower would have

been a challenge to design and construct even i it had been in London or Chicago.

But this is especially true in Guangzhou, where the humid climate will rigorously

test the high-perormance acade as well as the radiant cooling and resh air

systems and the associated controlsystems. On the other hand,

it is likely that most, i not

all, o the buildings compo-

nents will be obtained rom

within China, substantially

reducing the embodied

energy consumption that

has become prevalent in

construction projects in the

Western Hemisphere.

Although ultimately

the design or this project

resulted in a structure that

will not achieve a net zero-

energy status, the process has

provided strong analytical evi-

dence that the original goal isindeed possible. When com-

plete, the Pearl River Tower

will help China lead the way in

developing supertall buildings

that use energy with the utmost

eciency. n

Roger E. Frechette III, P.E., LEED

AP, is the director of sustain-

able engineering and Russell

Gilchrist the director of techni-

cal architecture for Skidmore,

Owings & MerrillLLP, of

Chicago. This article is based

on a paper the authors presented

at the Council on Tall Build-

ings and Urban Habitats 8th

World Congress (Tall and

Green: Typology for a Sus-

tainable Urban Future),

which was held in Dubayy

(Dubai) in March 2008.

Project credits Owner: Guangdong Tobacco

Company, Guangzhou, China Architect and engineer: Skidmore, Owings

& Merrill llp, Chicago Wind tunnel testing and computational fuid

analysis: Rowan Williams Davies & Irwin, Inc., Guelph, Ontario


The cumulative benet o all the environmentallybenecial strategies included in the design o thePearl River Tower will signicantly reduce the

amount o energy needed to operate the building.

The design o the Pearl River

Tower initially envisioned the

use o microturbine technology

to generate clean power in an

ecient and environmentally

responsible manner. Although

these plans were placed on inde-

nite hold when the Guangzhou

utility decided that it would not

connect the microturbines to the

local electrical grid, the buildings

basement can be retrotted to

accommodate the devices should

the utility change its stance.

The acade will

eature an internally

ventilated double-wall system that

incorporates a motorized venetian

blind system controlled by a photo-cell that tracks the movement

o the sun. The exterior glaz-

ing will take the orm o

insulated, tempered glass

with a low-emissivity coat-

ing; the inner layer will

be an operable clear glass

panel that can be opened

or maintenance.


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