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Jonathan Shrift

ENVS 664-660 Sustainable Design

10/21/2010

Project: Green Buildings

Commerzbank Tower

WhiletheCommerzbankTowerisnotrecognizedintheformLEEDcertication,theprojectisrecog-

nizedastherstEcologicalSkyscraperanditstillcanbeseenasinnovativeeventoday.Thetowerwascom-

pletedin1997.ThedaytheCommerzbankopened,theFinancialTimesadopteditasthesymbolofFrankfurt.

ItfeaturesBigBenandtheEiffelTowerassymbolsofLondonandParis.Itstoodasthetallestbuildingin

Europefromtheyearofitscompletionto2005.AlthoughthetowerhasbecomeameaningfulsymbolofGer-

manyseconomy,itisatrueexampleofusinginnovativedesignstrategiestoachievemaximumperformance,withminimalenergyuse,whileachievingahigherstandardoflivingforthebuildingsinhabitants.Thetower

wasdesignedbyNormanFoster,anarchitectwellknownforhisinnovativesustainablepractices.

BeforeanalyzingtheenvironmentallyfriendlysystemsthatCommerzbankToweremploys,it sworth

notingthatthenumberonegoalofFostersdesignistocreateapleasantworkenvironmentforthebuildings

2,000+occupantsasameansofincreasingworkerproductivityandmoral.Evenmodestimprovementsin

productivity,absenteeism,and/oremployeeretentioncansubstantiallyoutweighthetraditionallysoughtafter

efciencybenetssuchasenergysavings.Weoftensystematicallyunderinvestinoneofthemostvaluable

aspectsofbuildings,occupantexperience.Greenbuildingincludesanumberofstrategiesthatareintendedto

worktogethertocreateandsustainhealthy,comfortableindoorenvironments.Aswithneighborhoods,these

greenbuildingstrategiesaremostoftenprescriptiveorformbasedmetrics,inthisprojectscasemeasuresof

accesstodaylightorventilationratesarekey.Mostlargeofcebuildingsbuilttodayrelyheavilyonmas-

sivemechanicalsystemstoheat,cool,andcirculateair,andhighlevelsofwattagetoarticiallylightthespace

within.Inusualcasesonlyasmallpercentageofofcesorworkspaceshavedirectaccesstodaylightandfresh

air.Fosterreliesonauniquehybridsystemthatlights,cools,andventilatesthebuildingusingminimalman

madeenergy.

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Greenbuildingisasystematiceffortto

create,sustain,andacceleratechangesinpractice,technology,and

behaviortoreducebuildingrelated

environmentalimpactswhilecreating

placesthatarehealthierandmore

satisfyingforpeople.Theobjective

istoreducethenegativeimpactsof

builtenvironmentswhilecreating

healthy,comfortable,andeconomically

prosperousplacesforpeopletolive,

work,andplay.

- USGBC

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Fostershybridsystem,andthekeytothisbuildingssuccessastherstecologicalskyscraper,is

embeddedinthepassivebenetscreatedfromaninterconnectedseriesofatriumspaces.Itisreferredtoasa

hybridsystembecausethisoneintegrateddesignstrategy(thenetworkofatriums)lights,heatsorcools,and

ventilatesthebuilding,whilecreatingahigherstandardoflivingallatonce.Lightaswellasoutsideairisfed

tothecenterofthebuildingthroughtheroofandatrium,andthroughninegardensthatarefourstoriestall.The

gardensspiralaroundthebuildingfaadeandconvertcarbondioxidegastooxygenasitentersandleavesthe

buildingthroughmechanicalvents. Allofceshaveaccesstonaturalsunlightandareableto

beopentonaturalventilationwhethertheyarefacingtheexterior

orinteriorofthebuilding.Peoplewithinteriorbackingofces

mayopentheirwindowstotheatrium,whilepeoplewithexterior

backingofcesmayopentheirwindowspartwaytotheoutside.

Outsideopeningwindowsaremadefeasiblebyadoublelayerglazing

system.Therstlayerofglazinghasoperablewindowsthatopen

intoacavitybetweenasecondlayerofglazing.Thesecondlayerof

glazingallowsfreshairtoenterthroughventilationslotsandcontrols

relativeairowandwindforces.Thewindowsofthebuilding

havebeenselectivelychosensothatthereisnointerferencewith

sunlightpassage.Laminatedglasswithouttintallowsamaximum

amountofsunlightintothetowerinsteadofreectingitaway.Foster

workeddirectlywithDuponttodevelopatransparentglassthat

wouldhavethepropertiesofbothclearglazingandarebarrier.

Commerzbanksuseofthedoughnutplaninconjunctionwiththe

four-storyskygardensallowsforeveryofceinthebuildingtohaveanunobstructedviewtotheoutdoors.Fullheightwindowsand

shallowoorplatesensurethattheamountofnaturallightpenetrating

intothebuildingissufcientenoughtosubstituteforarticial

lightingthroughthemajorityoftheworkday.Frankfurt,Germanys

lowsolarinsolationanddiffuselightingconditionsmakedaylighting

anincrediblyeffectiveenvironmentalresponseinthatglareand

unwanteddirectsolargainintheregionisminimal.

NaturalventilationinCommerzbankoccursatmultiplescalesrangingfromindividualroomstoseveral

buildingstories,allofwhichvarybasedonclimaticconditions.Whenlookingatthebuildingsectionasa

whole,itappearsasthoughtheentirecentralatriumspaceactslikeagiantchimneywithairbeingexhausted

outthetopofthebuildingbywayofstackeffect.WhilethiswasFostersoriginalintentionwhendesigningthe

building,theincrediblescaleofthespacewouldhaveresultedinapowerfulupdraftofairthatwouldhavebeen

undesirableforthebuildingpatrons.Consequently,inthenaldesign,theatriumissegmentedbyglassdecks

intofourtwelve-storyspaces,eachconsistingofthreedeliberatelypositionedskygardens.Inthisparticular

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scheme,freshairentersthebuildingthroughwindwardgardensatthebottomofeverytwelve-storysegment,

andexhaustedoutofleewardgardensatthetopofthem.Theglassdecksarecompletelysealedofffromthe

atriumspacebelow,divorcingthemfromthetowersnaturalventilationprocess,whichincludesbothcross-

ventillationandalimitedamountofstackeffect.Themeansbywhichnaturalventilationoccursinthetower

sectionvariesforthecoldwinterandwarmsummermonths.Incoldwinterconditions,skygardenwindowsare

closedtostoreheat,butarereopenedtoletindesirablebreezeswhenconditions

modernofcebuildingsfullofheat-producingmachineryhaveahigherdemandforcooling,butFrankfurtwinterstypicallyrequireheatingaswell.Fosterrespondstothisdichotomyofneedsinthecladdingsystemby

utilizingdoubleskinglazingwithventilatedcavityspaces,operablecasements,andVenetianblinds.Whenever

heatingisdesired,exteriorventsareclosedtoallowheattobuildupinthecavityspaces,whichprotectsagainst

coldwindswhileimprovingthethermalinsulatingpropertiesofthewindowsbyasmuchas20%.Whencooling

isrequired,thecavityventsandoperablecasementsareopenedtoallowfornaturalventilationwithcoolair

enteringlowandwarmairexitinghighaftercirculatingthroughtheofce.

Commerzbanktower sninefour-storyskygardensoccupythreedifferentfaces,whichallhavedistinct

solarorientations.Withgardensorientedtothesouth,east,andwest,thedesignteamrecognizedearlyon

thatplantingsfromdifferentclimateswouldberequiredtorespondtothevaryinglevelsofsolarexposure.

Thesouthfacinggardens,whichreceivethemostamountofsolargainthroughouttheyearconsistprimarily

ofMediterraneanplantingsincludingolivetrees,cypresses,andagroundcoverofthyme.Thewestfacing

gardens,whichreceiveasignicantamountofafternoonsunthroughouttheyeararelledwithnorthAmerican

plantsincludingevergreenoaksandornamentalgrasses.Thenortheastfacinggardens,whichreceivevery

littletonosunoverthecourseoftheyeararecomposedofvariousAsianplantingsthatthriveinshaded

environmentssuchasbamboo.Toensurethatalloftheplantlifestaysalive,theskygardensarealways

naturallyventilated,evenwhentheofceinteriorsarebeingairconditioned.Asaresult,theseenvironmentsact

moreasshelteredexteriorspacesthaninteriors,meaningthattherearetimesintheyearwhentheymaybetoocoolforpeopleinindoorclothing.Thisissomewhatsupplementedwithunderoorheating,butisanadjustment

thatwouldprobablynotbeaswidelyaccepted.

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Glassdecksorskylightsatlevels7,19,31,and43alongwiththeenclosingtopskylightdividetheatrium.The

useofmultipleskylightenclosureshasmorethanonefunction.Ahalf-hourreandsmokebarrieriscreated

betweensectionsofthebuildingalongwithmanagingandcontrolthefreshairventilationinthebuilding.The

skylightsdividethestackandchimneyeffectleadingtoanincreasecontrolofairqualitymanagement.

Whilepassivestrategiesforheating,cooling,andventilationareeffectivelyimplementedin

Commerzbankofcespacesforthemajorityoftheyear,Frankfurtscoldwintermonthsandhotsummer

periodrequireactivesystemsasameanstocreatethermalcomfortwithinthetower.Wheninactivemodes(asdeterminedbythecentralbuildingmanagementsystem),Commerzbankofcesutilizeradiantoorheatingto

effectivelywarmobjectsinsteadofair,

Whiletheprojectisfulloftrulygeniusandinnovativeprincipals,therearesomecriticismstowards

it.Somepeoplecriticizeitforitslackofrenewableenergysources.Peoplearealwaysquicktoapplysolar

panelstoabuildingtoconsideritsustainable.ThetruthisthatPVswouldnotworkinGermanyscloudy

climate.WindturbinescouldbeafeasibleoptionanditwouldhavebeeninterestingtoseehowFosterwould

haveintegratedthemintothedesign.Anothercriticismisthatitdoesnotuserecycledcontentmaterials.What

alotofpeopledonotknowisthatsteelisactuallymostlyrecycledcontentanyway.Whileitistruethatthis

buildingmaynotmeeteverycategoryofasustainablebuildingpractices,theuniquesystemofatriumspaces

andgardensreallysetsitapartfromothergenerictowers.

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Works Cited

Cramer,Ned.EuropesTallestTower.ArchitectureAugust97,Vol.86Issue8

Davey,P.Highexpectations.TheArchitecturalReviewJuly97,Vol.202Issue1205

Davies,Colined.BirkhauserandJenkins,Davided.NormanFosterWorksVol.4.Munich;NewYork:Prestel,

c2002.

Fischer,Volker.SirNormanFosterandPartners:Commerzbank,FrankfurtamMain.Stuttgart:AxelMenges,

1997.

Lambot,Ian.CommerzbankFrankfurt:PrototypeforanEcologicalHigh-Rise.Boston:WatermarkBirkhuser,

1997.

Wigginton,Michael,andJudeHarris.Intelligentskins.Oxford:Butterworth-Heinemann,2002.

ArchitectureWeek:IlluminatingFosterhttp://www.architectureweek.com/2000/0913/design_1-1.html

Archpedia:NormanFoster

http://www.archpedia.com/Architects/Foster.html

BBCNews:NormanFoster:Buildingthefuture

http://news.bbc.co.uk/hi/english/uk/newsid_742000/742087.stm

Dupont:SirNormanFosterandPartners:Exploitingtheultimateexibilityinlaminatedglass

http://www.dupont.com/safetyglass/lgn/stories/1105.html

FosterandAssociates:CommerzbankHeadquarters

http://www.fosterandpartners.com/internetsite/html/simple.html

FosterAssociates:RecentWorks.NewYork:St.MartinsPress,1992.

FromheretoModernity:NormanFoster

http://www.open2.net/modernity/4_9.htm

Hypermart:CommerzbankFrankfurtGermany

http://a4d.hypermart.net/architecture/projects/combank/combank.shtm

Lehigh:BuildingoftheMonth-CommerzbankTower

http://www.lehigh.edu/ctbuh/bom_com.html

PrincetonArchitecturalPress:CommerzbankFrankfurtPrototypeforanEcologicalHighrise

http://www.papress.com/books/birkhauser/3764357401.html