Value based Design

DAV ANALYSIS

COMMERZBANK TOWER FRANKFURT, GERMANY

Yasha I Laleh I Jessica image source : www.fosterandpartners.com

OUTLINE • INTRODUCTION

• • • • •

MOTIVATION LOCATION BUILDING FACTS CONSTRUCTION TIMELINE SPIN & BUZZ

• STAKEHOLDERS • FEATURES • DAV ANALYSIS

• DOUBLE SKIN FAÇADE • VIERENDEEL FRAME SYSTEM • CONCLUSION

• REFERENCES Image source: www.commerzbank.de

COMMERZBANK TOWER, DAV ANALYSIS

MOTIVATION • • • • • •

Focus on user health and indoor environment conditions quality Sustainable design - World’s first ecological office tower Bringing Nature to indoor spaces - sky gardens Renowned Architect - Foster and partners Renowned structural engineers – Arup and partners Frankfurt's landmark - Tallest skyscraper in Germany (300m)

“An ambitious structural and aesthetic vision with a quest for natural ecological solutions and the wellbeing of the individual” - Norman Foster

Source: www.fosterandpartners.com

COMMERZBANK TOWER, DAV ANALYSIS

LOCATION

COMMERZBANK TOWER, DAV ANALYSIS

• Frankfurt, Germany Business district Historical district

• Located in the heart of the business district in Frankfurt

Images source: www.fosterandpartners.com , www.google.com/maps

BUILDING FACTS

COMMERZBANK TOWER, DAV ANALYSIS

INFORMATION

SOURCE

TYPE

Office skyscraper

Foster & Partners

CONSTRUCTION PHASE

1994-1997

Lambot et al.

DESIGN PHASE

1991-1993

Lambot et al.

GROSS AREA

85,503m2

Commerzbank

WORKPLACES

2400

Foster & Partners

HEIGHT

259m(excluding antenna) 300m(with antenna)

Commerzbank

LEVELS

53

Foster &Partners

COST

$300m

Arend et al.

GROSS VOLUME

538,000m3

Commerzbank

STRUCTURE

Steel structure with Vierendeel frame system

Commerzbank

Image source: www.fosterandpartners.com

DEVELOPMENT OF DESIGN 1960-1980’s Early 1980’s 1989

Feb 1991

Feb-Mar 1991

Mar 27-Jun 3

COMMERZBANK TOWER, DAV ANALYSIS

-Commerzbank occupies 30 building and looks to consolidate -local government restricts development of new skyscrapers (due to public outcry) -Public dislike of skyscrapers relaxes -Site becomes available for construction of new Commerzbank headquarters but only if meets government demands -Structure must benefit Frankfurt public -Address environmental concerns -Include international companies in biding process -12 design companies invited to bid (9 Germany, 2 USA, 1 Britain) with a June 3rd deadline Foster Design -pinwheel/projecting wings allow all office to be naturally lit, but large surface area of façade makes design too expensive -center atrium provide natural lighting to internal space -triangular plan prevent building from directly facing old Commerzbank Tower -Sky gardens on south side and contain elevators structural load concerns -Sky garden on all sides distribute structural load and move elevators/utilities to corners, column free space

Source: Davies & Lambot, 1997

CONSTRUCTION TIMELINE 1989 Site Selection

1991

April: Piling completed June: main foundation completed Aug: steel frame reached level 7 Oct: steel frame reached level 29 Dec: First cladding panels arrived Steel frame reached level 41

Source: Lambot et al.

1992

3 June: Deadline for Design Competition 9 Germany-2 USA-1 Britain Foster and Partners Declared the Winner Sep: Detailed design progressed

1995

COMMERZBANK TOWER, DAV ANALYSIS

1996 Jan: Steel frame reached level 51 March: Steel frame completed Installation of building services started Atrium and exterior facade cladding reached level 27 Dec: The 40 m long antenna lifted into position

Sep: Cost simulation, review of complete strategy

1997 March: installation of interior fixtures, garden trees delivered 24 July: Officially opened.

1993 Sub-contractors hired

1994 Aug: Construction started with foundation construction

SPIN & BUZZ

COMMERZBANK TOWER, DAV ANALYSIS

BOOKS: Sir Norman Foster and Partners : Commerzbank, Frankfurt am Main, Fischer, V. 1997, Berlin

Commerzbank Frankfurt : prototype of an ecological high-rise, modell eines ökologischen Hochhauses Davies. C, Lambot. I 1997, UK

AWARDS: • • • •

Green Building Award of the City of Frankfurt – Commerzbank RIBA Architecture Award - Commerzbank Headquarters, Frankfurt Bund Deutscher Architekten - Martin-Elsaesser-Plakette Award - Commerzbank Headquarters, Frankfurt British Construction Industry Awards, International Award to Commerzbank Headquarters

OTHER MEDIA: • • • •

Appears in the Euro Contemporary tile set in SimCity 4 (Deluxe or with Rush Hour) A 3D puzzle of Commerzbank tower Made To Scale Collection released by Wrebbit Featured as a default background for the Motorola RAZR cell phone Featured in the Covert Affairs episode: Levitate Me

Source: www.fosterandpartners.com / library.cmu.edu

STAKEHOLDERS

COMMERZBANK TOWER, DAV ANALYSIS

CATEGORY

FAME

FORTUNE

FUNCTION

SUSTAINABILITY

Client - Commerzbank

X

X

X

X

ArchitectFoster & Partners

X

X

X

X

Structural EngineerArup & Partners

X

X

-

-

Media

X

-

-

X

City of Frankfurt

X

-

X

X

Authorities

X

-

X

X

Contractor

X

X

-

-

Faรงade fabricators(Josef Gartner and Co.)

X

X

-

X

Users

-

-

X

X

FEATURES • Form and Shape • Sky gardens

• Double skin façade (DAV analysis) • Steel Structure (DAV analysis)

COMMERZBANK TOWER, DAV ANALYSIS

FEATURES • Form and shape •

Hollow triangular floor plan with curved corners (Manipulates wind moment, Unique triangular shape)

•

Full height atrium(Allows in natural light, Allows visibility into sky garden)

•

Non-tapering form

•

Total floor area – 85,503 m2 (1,613 m2 per floor)

•

Height, 300 m

Images source: www.fosterandpartners.com , Arend et al.

COMMERZBANK TOWER, DAV ANALYSIS

FEATURES

COMMERZBANK TOWER, DAV ANALYSIS

• Sky gardens •

9 Naturally ventilated sky gardens

•

3 ecologies (Asian, N. American, Meditterrian)

•

Evenly distributed day light (high glazed external walls, reflective ceiling)

•

4 stories tall, situated between two eightstory tall stacks of offices

•

Communal space

•

Provides natural ventilation, passive heating/cooling, outside view and daylight for workplaces

Spiraling sky gardens

DOUBLE SKIN FAÇADE- Description

COMMERZBANK TOWER, DAV ANALYSIS

• Design • Exterior skin- disjointed sections of fixed glass 1.4m x 2.25m sheets of 8mm toughness glass with 20cm gap (Poirazis, 2004) • Interior skin- double-glazed operable windows 3,100 motorized interior windows- controlled by user or monitoring system (MIT, 2000) • Function • Use passive heating, cooling and ventilation • Reduce energy consumption • Create Transparency • Acoustical Reduction

Façade engineer – Gartner and Co.

Image Source: (Volker, 2013)

DOUBLE SKIN FAÇADE- Description

Passive Source: Gartner and Co., Arend et al

COMMERZBANK TOWER, DAV ANALYSIS

Active

DOUBLE SKIN FAÇADE-DAV Analysis

COMMERZBANK TOWER, DAV ANALYSIS

COSTS & RISKS Stakeholder

Qualitative

Envelope engineer – Josef Gartner and Co.

-design must withstand high finds and high moisture -potential for building to act differently than modeled -condensation obstruct view of nature

Architect- Foster

Client

-potential for façade to be used less than predicted value of 60% of year

User

-variation in indoor environment due -potential for glare -teach workers double façade system installation -glass was delivered on a as-needed basis (potential for construction delays)

Contractor

Quantitative

Sources (Hartkopf, 2013)

-4 surfaces of glass to clean as opposed to 2 for conventional façade (increase cleaning cost) -operable windows increase maintenance costs -Cost of cooling system -$15 million dollars to do research on facades for high wind and moisture environment

-more time intensive than single facade

(Hartkopf, 2013)

DOUBLE SKIN FAÇADE-DAV Analysis

COMMERZBANK TOWER, DAV ANALYSIS

BENEFITS Stakeholder

Qualitative

Quantitative

Façade engineer – Josef Gartner and Co.

-made way for future double facades in Germany

-$15 million dollars to do research on facades for high wind and moisture environment

(Hartkopf, 2013)

Architect- Foster

-emphasizes idea of ecological tower -utilizes sustainability -adds transparency -reduces energy consumption for ventilation, heating and cooling

-NPV = $30.4 million -annual energy savings = $484,000 -Natural ventilation 80% of year (originally estimated to be 60%)

(Foster & Partners) (Gartner & Co.)

Client

User

-user control work space -environment conducive to working (natural light, natural ventilation, access to nature) -visibility/ transparency

Sources

(Poirazis, 2004)

DOUBLE SKIN FAÇADE- NPV Calculations Floor to floor height = 3.75m Surface Area of façade = (24+34+36 office wings)(3.75m)(34m) =11,730m2 Material & Construction = (Cost per m2)(Double skin area) = ($915.83/m2 )( 11,730m2 ) = $10,742,742 in 2003$ Research Investment = $15 million in 1994$ Operating Costs = ( 7 €/m2 )* ($1/(1.0919 €))(11,730m2 ) = $75,200 per year in 2003$ Cleaning Costs =( 3.9 €/m2 )* ($1/1.0919 €)(11,730m2 ) = $41,900 per year in 2003$ NPV = $30.4 million

COMMERZBANK TOWER, DAV ANALYSIS

Source (Davies & Lambot, 1997) (Davies & Lambot, 1997) (Poirazis, 2004)

(Volker, 2013) (Poirazis, 2004)

(Poirazis, 2004)

DOUBLE SKIN FAÇADE- Savings Calculations Commerzbank uses passive heating, cooling and heating for 80% of year

COMMERZBANK TOWER, DAV ANALYSIS

Source (Foster & Partners) (EIA, 2003)

Electricity Consumption for Conventional Office Building = 15.5 kWh/ft2 Area of floor area = 920,314 ft2 Ventilation = 5% of total electricity Space Heating & Cooling = 48% of total electricity Energy Savings = (80%)[(53%)(15.5 kWh/ft2)(920,314ft2) = $464,000 per year

(See below) (EIA, 2003) (EIA, 2003) (EIA, 2003)

**Potential for additional savings to due user health and productivity benefits** Source: “Commerzbank Head Office.” https://www.commerzbank.com/media/konzern_1/konzerninfo/hochhaus_1/commerzbank-tower-facts.pdf

DOUBLE SKIN FAร ADE- BENCHMARKING

COMMERZBANK TOWER, DAV ANALYSIS

Type of Faรงade

Investment Cost [$/m2]

Running Cost [$/m2]

Standard faรงade

$405-$675

$3.38-$4.73

Double skin standard

$811-$1082

$5.41-$10.14

Double skin w/ adjustable air inlet and outlet

$947-$1352

$14.74

Double skin with openable exterior sashes

$1082-$1758

N/A

Running Cost includes maintenance and cleaning costs Cleaning- interior faces cleaned once a year, exterior face cleaned twice a year and shading devices (exterior once a year, interior every five years) Source: (Poirazis, 2004), BBRI

DOUBLE SKIN FAÇADE- BENCHMARKING Location

Commerzbank Tower

Arag 2000 Tower

Torre de Cristal

Bligh skyscraper

Frankfurt, Germany

Dusseldorf, Germany

Madrid, Spain

Sydney, Australia

1997

2000

2009

2011

300m (53)

125m (31)

250m (45)

139m (30)

85,500 m2

38,100 m2

77,000 m2

42,700 m2

Foster and partners

RKW, Dusseldorf - Foster and Partners

César Pelli

Architectus Ingenhoven Architects

Completion Year Height (stories) Area

Architect

COMMERZBANK TOWER, DAV ANALYSIS

Facade

Segmented fixed exterior with operable interior windows

Shaft-box system

Ventilated curtain wall with automatic blinds

An inner sealed skin of doubleglazed units and a ventilated outer skin of clear glass

Total cost

$300 mil

$63mil

$ 340 mil

$270 mil

Source: Foster and partners,

DOUBLE SKIN FAÇADE- BENCHMARKING

COMMERZBANK TOWER, DAV ANALYSIS

AESTHETICS

Commerzbank Tower

Arag 2000 Tower

Torre de Cristal

Bligh Skyscraper

Weight

PERFORMANCE

Commerzbank Tower

Arag 2000 Tower

Torre de Cristal

Bligh Skyscraper

Weight

Commerzbank Tower

1

7

2

5

0.54

Commerzbank Tower

1

4

1

1/3

0.19

Arag 2000 Tower

1/7

1

1/5

1/3

0.06

Arag 2000 Tower

1/4

1

4

1/7

0.08

Torre de Cristal

1/2

5

1

4

0.29

Torre de Cristal

1

1/4

1

1/3

0.11

Bligh skyscraper

1/5

3

1/4

1

0.10

Bligh skyscraper

3

7

3

1

0.55

1.84

16

3.45

10.33

5.25

12.25

9

1.81

Commerzbank Tower

Arag 2000 Tower

IMPACT ON OCCUPANTS

Scale Torre de Cristal

Bligh Skyscraper

Weight

1

1/5

1/5

1

0.08

5

1

1/2

6

0.30

Torre de Cristal

5

2

1

7

0.54

Bligh skyscraper

1

1/6

1/7

1

0.07

12

3.37

1.84

15

Source: Akin, 2013

Torre de Cristal

0.94

Commerzbank Tower

0.81

Bligh skyscraper

0.72

Arag 2000 Tower

0.44

one over another

5: Strong or essential Arag 2000 Tower

Score

1: Equal importance 3: Moderate importance of

Commerzbank Tower

Building

importance

7: Very strong or demonstrated importance

9: Extreme importance 2,4,6,8: Intermediate values

Max score of 3

DAV FEATURE ANALYSIS – Vierendeel System

COMMERZBANK TOWER, DAV ANALYSIS

• First skyscraper in Germany to incorporate steel as its main structural component • Standardized 8 story Virendeel truss system • To support weight of steel, three mega columns consisting of h-framed steel columns with diagonal bracings encased in concrete were used on the vertices of the triangular plan.

• Piles Foundation to support steel structure 8 story Virendeel truss

image source - http://www-classes.usc.edu/architecture/structures/Arch513/lectures/08-vierendeel.pdf

DAV FEATURE ANALYSIS – Vierendeel System • Structural Engineer - Arup & Partners

• Contractor - Hochtief AG • Beginning of Installation - June 1995 • Total time taken - 12 months

image source - http://www-classes.usc.edu/architecture/structures/Arch513/lectures/08-vierendeel.pdf

DAV FEATURE ANALYSIS – Vierendeel System QUANTITATIVE FACTS S.No.

Description

Quantity

Unit

1

Total amount of steel used

18,800

tons

2

Vierendeel system

9000

tons

3

Horizontal member size (upto 65mm thk)

475 x 1100

m

4

Vertical member size (upto 85mm thk)

475 x 1000

m

5

Total Horizontal member length

5406

m

6

Total Vertical Member lengths

1908

m

7

No. of floors

53

DAV FEATURE ANALYSIS – Vierendeel System COSTS • Total Steel used in Vierendeel System – 8954 tons • Material cost – $ 2375/ ton • Labor - $ 425/ ton • Equipment – $ 140/ ton • Total Cost of steel used for Vierendeel system - $ 31.5 million • NPV - $ (31,500,000 (1+0.0274)2013-2010 = $ 34.16 mil

DAV FEATURE ANALYSIS – Vierendeel System COSTS & RISKS Stake Holder

Qualitative

Client - Commerzbank

• Construction was less time consuming

Structural EngineerArup & Partners

•

• • Contractor

Users

First building in Germany to incorporate structural steel as its main structural component Risk of settlement in neighboring buildings because of clay soil Simpler structure, repetitive details -

•

Risk of settlement in neighboring buildings because of clay soil

Quantitative Weight of the building Is 132,000 tons = Old 32 story commerzbank tower

• Fire proofing @$1000/ton = $ 10 million (Added cost)

-

DAV FEATURE ANALYSIS – Vierendeel System BENEFITS

Stake Holder Client Commerzbank

Qualitative • •

Architect - Foster & Partners

• • •

Structural EngineerArup & Partners

•

Users

• •

•

Quantitative

Source

Tallest skyscraper in Germany Currently 8th tallest in Europe

• Rent Increment

Non Tapering Form Pre Fab Assembly, ease of construction Standardization

• Increase in rentable space on top floors • Allowed for 25% more glazing area than a concrete vierendeel system

Pre Fab Assembly, ease of construction Reduction in weight

• Reduces assembly time due to uniformity by 20%

Lambot et al

Column free spaces Allows spatial reconfiguration

• -Use of steel allows 400sq.m of column free space (compared to concrete) • CS - reduces turnover costs of $4100 per person, based on an average annual salary of $45,000

Arend et al

Foster & Partners

Fitz-Enz, 2000

VIERENDEEL SYSTEM- BENCHMARKING

COMMERZBANK TOWER, DAV ANALYSIS

COMMERZBANK TOWER

SILBERTURM TOWER

JOHN HANCOCK CENTER

HEARST TOWER

Building Type

Office building

Office building

Office building

Office building

Location

Frankfurt, Germany

Frankfurt, Germany

Chicago, USA

New York, USA

Architect

Foster & Partners

ABB Architekten

Skidmore, Owings & Merrill

Foster & Partners

Structural Engineers

Arup & Partners

BGS Ingenieursozietat

Skidmore, Owings & Merrill

The Cantour Seinuk Group

VIERENDEEL SYSTEM- BENCHMARKING

COMMERZBANK TOWER, DAV ANALYSIS

COMMERZBANK TOWER

SILBERTURM TOWER

JOHN HANCOCK CENTER

HEARST TOWER

Type of structure

Steel Vierendeel system

Concrete structure

Tubular system with cross bracing

Diagrid steel frame

Amount of steel used

18,800 tons

-

46,000 tons

10,480 tons

Material cost

$ 45 million ($ 2375/ ton)

-

$ 109 million ($ 2375/ ton)

$ 25 million ($ 2375/ ton)

Height (Stories)

259m (53)

166m (32)

344m (100)

182m (46)

Construction

1994-1997

1972-1978

1965-1969

2003-2006

Cost

$ 300 mil

-

$100 mil

$500 mil

VIERENDEEL SYSTEM- BENCHMARKING AESTHETICS

Commerzba nk Tower

John Hancock Center

Hearst tower

COMMERZBANK TOWER, DAV ANALYSIS

Silberturm

Commerzbank Tower

John Hancock Center

Hearst tower

Silberturm

Weight

PERFORMANCE

Weight

1

3

5

7

0.60

Commerzbank Tower

1

5

1/3

6

0.23

Commerzbank Tower

John Hancock Center

1/5

1

1/5

3

0.09

John Hancock Center

1/3

1

3

5

0.22

Hearst Tower

3 1/6 4.37

7 1 1.70

0.60 0.06

Hearst Tower

1/5

1/3

1

4

0.11

Silberturm

1/7

1/5

1/4

1

0.06

1.68

4.53

9.25

17

Silberturm

EASE OF CONSTRUCTION

Commerzbank Tower

5 1 1/3 1/7 11.33 1.68 John Hancock Center

Hearst tower

Scale

Silberturm Weight

1

4

4

8

0.62

1/4

Hearst Tower

1/4

1

1

5

0.16

demonstrated importance

Silberturm

1/8

1/5

1/5

1

0.05

9: Extreme importance

1.63

6.20

6.20

19

Source: Akin, 2013

5

0.16

1.45

Hearst Tower

0.87

John Hancock Center

0.45

Silberturm

0.17

importance

John Hancock Center

1

Commerzbank Tower

one over another

5: Strong or essential

1

Score

1: Equal importance 3: Moderate importance of

Commerzbank Tower

Building

7: Very strong or

2,4,6,8: Intermediate values

Max score of 3

IMPACT ANALYSIS

COMMERZBANK TOWER, DAV ANALYSIS

1st order

2nd order

3rd order

(construction phase)

(0-3 years)

(3-10 years)

Client - Commerzbank

--

+

+++

ArchitectFoster & Partners

+

++

+++

Structural EngineerArup & Partners

+

+

++

Media

+

++

0

Frankfurt InhabitantsPublic

---

+

++

Authorities

0

++

+++

Environment

-

+

++

Contractor

++

0

0

Faรงade fabricators(Josef Gartner and Co.)

++

+

0

Users

0

+++

+++

CATEGORY

CONCLUSION

COMMERZBANK TOWER, DAV ANALYSIS

LIMITATIONS & DIFFICULTIES OF OUR STUDY • DAV Analysis of only two features of building • Difficult obtaining information from primary source • Some information found in German, so we were unable to understand • Unable to find revenue generated from restaurant, retail and parking rental specific to Commerzbank Tower • Some assumptions made on costs and quantities by using data from similar buildings/ feature • Time

CONCLUSION

COMMERZBANK TOWER, DAV ANALYSIS

OBSERVATIONS • Double skin facade • Driving force was energy consumption and employees’ quality of life while working •

Vierendeel system • Driving force was a non-obtrusive form capable of supporting a high rise structure and sky gardens

• Additional physical building features (form & shape and sky gardens) are equally important for DAV analysis because of their energy efficiency and user benefits, but they not feasible to do because of the lack of data • Commerzbank Tower served as a catalyst for sustainable development in Frankfurt • Successful execution of design DAV parameters (features and functions) starts with good collaboration and communication between architect and engineers

SOURCES • • • •

• • • •

• • • •

• • • •

COMMERZBANK TOWER, DAV ANALYSIS

Poirazis, Harris. Double Skin Facades for Office Buildings. Department of Energy and Building Design. (2004). pg 77-78 Leaman, Adrian (2001) Productivity Improvement. Buildings in Value, Vol. 3, Ch. 19.Building Use Studies Ltd., 2001.

Fjeld, T, B. Veiersted, L. Sandvik, G. Riise, F. Levy (1998) The effect of indoor foliage plants on health an discomfort symptoms among office workers. Indoor & Built Environment, 7, pp. 204-209.

Mackey, Jennifer. Evaluating workspaces in European sustainable high rise buildings- assessments, responses and speculations from the inhabitants. University of Florida.(2010) “CO2 Accounting Energy Use.” http://sustainability2009.commerzbank.com/reports/commerzbank/annual/2009/nb/English/703025/co_sub_2_s ub_-accounting-energy-use.html. Commerzbank AG. (November 30, 2009). Accessed September 2013 Goncalves, J & Bode, K. “The importance of real life data to support environmental claims for tall buildings.”

(2011) Fischer, Volker. Sir Norman Foster and Partners : Commerzbank, Frankfurt am Main. Stuttgart : Axel Menges, 1997.

Lambot, Ian. Commerzbank Frankfurt: Prototype for an Ecological High-Rise. Boston : Watermark Birkhäuser, 1997.

Foster & Partners. "Commerzbank Headquarters." http://www.fosterandpartners.com/projects/commerzbankheadquarters/ Accessed September 2013.

Arend, John; Benkert, Mike; deFilippis, Audrey; Tillmaand, Saretta. “Commerzbank Tower.” http://www.mbenkert.com/arend.benkert.defilippis.tillmaand.pdf Accessed September 2013 “Commerzbank Head Office.” https://www.commerzbank.com/media/konzern_1/konzerninfo/hochhaus_1/commerzbank-tower-facts.pdf Accessed September 2013 Arup & Partners. “Commerzbank.” http://www.arup.com/Projects/Commerzbank.aspx (2013/2014). Accessed September 2013 Akin, O. More VBD Analysis Methods(2013): Optimization, Xtreme Design and AHP lecture for Value Based Design course Hartkopf, Volker. “Towards a Sustainable Future: Integrating Environmentally and Economically Future Proof Technologies and Practices” NSF/IUCRC Annual Meeting, Jan 2013 Washington DC EIA. “2003 EIA Commercial Building Energy Consumption Survey (CBECS)” http://www.eia.gov 2003

SOURCES • • • • • • • • • • • • • • • • • • • • • • • • •

COMMERZBANK TOWER, DAV ANALYSIS

http://www.pbs.org/wgbh/buildingbig/wonder/structure/john_hancock.html http://www.aviewoncities.com/buildings/chicago/johnhancockcenter.htm http://www.ritchiewiki.com/wiki/index.php/John_Hancock_Center http://www.hearst.com http://www.archdaily.com/204701/flashback-hearst-tower-foster-and-partners/ http://www.allaboutskyscrapers.com/property/torre-de-cristal http://www.australiandesignreview.com/architecture/17855-1-bligh-street http://cmiserver.mit.edu/natvent/Europe/rwe.htm http://www.rwe.com/web/cms/en/8308/rwe/about-rwe/profile/eco-tower/ http://www.academia.edu/180367/Innovative_Building_Skins_Double_Glass_Wall_Ventilated_Facade http://www.fosterandpartners.com/projects/hearst-tower/ http://www.fosterandpartners.com/projects/arag/ http://en.wikipedia.org/wiki/1_Bligh_Street http://www.flickr.com/photos/64210496@N02/6713563055/lightbox/ http://en.wikipedia.org/wiki/1_Bligh_Street http://en.wikipedia.org/wiki/RWE_Tower http://en.wikipedia.org/wiki/Arag-Tower http://en.wikipedia.org/wiki/Commerzbank_Tower https://www.commerzbank.de/en/hauptnavigation/presse/bilddaten/buildings/buildings_1.html http://www.officingtoday.com/2011/01/affirma-opens-business-center-on-roof-of-madrid/ http://www.emporis.com/building http://pcparch.com/project/torre-de-cristal http://twistarsphotography.com/?p=149 http://www.bdonline.co.uk/news/frankfurt%E2%80%99s-towering-letting/3139045.article http://www.bbri.be/activefacades/new/download/Ventilated%20Double%20Facades%20%20Maintenance%20and%20durability%20aspects%20-%20dfv1%20-%20final.pdf

COMMERZBANK TOWER, DAV ANALYSIS

END