William Rawn Associates, Architects, Inc. Boston, MA

CAMBRIDGE PUBLIC LIBRARYCAMBRIDGE, MA

CASE STUDY: A DOUBLE-SKIN GLASS WALL

Design Team: William Rawn Associates, Architects, Inc. with Ann Beha Architects

Seestern, Dusseldorf

SparkasseDusseldorf

Stadttor, Dusseldorf

ARAG 2000,Dusseldor

3. Other projects visited by design team:

1. First US project to incorporate all key ingredients of advanced European Double-skin curtainwall technology:

• 3’-0” Deep Airspace: provides added insulating depth and enables maintenance access

• Multi-story Thermal Flue: the greater height improves natural convection and makes the heat capture and exhaust more effi cient.

• Movable 1’-0” Deep Sunshades: locating the blinds in the protected cavity allows them to collect the sun’s heat energy before it enters the conditioned building. The lightweight aluminum louvers can be motorized to provide glare protection at all sun angles (important on a southwest exposure).

2. European examples of this type: The design team visited over 10 buildings with double-skin technology in Germany and London to determine how best to adapt this technology to a library. This research revealed the advantages of this type iof double facade in providing the level of transparency, thermal comfort, glare control, maintainability, and energy savings that were important for the library:

Bayer Headquarters, Leverkusen, Germany

Post Tower, Bonn, Germany

Helicon, London, England

A PIONEER OF DOUBLE SKIN CURTAINWALL TECHNOLOGY IN THE US

The facade was fabricated in Gundelfi ngen, Germany by Josef Gartner, GmbH. Prior to fabrication, a full scale mock-up of the facade was constructed and tested for air infi ltration, pressure, water penetration, and seismic deformation

A thermal model was created by Arup Facade Engineering (London Offi ce)

3’-0” Multi-story fl ue -- 12” deep operable sunshades in the cavity:

• Cambridge Public Library, Cambridge, MA (2009)

3’-0” Multi-story fl ue with operable narrow sunshades in the cavity:

• Information Commons, Loyola University, Chicago IL (2008)

3’-0” Multi-story fl ue - no sunshades in the cavity:

• Foundry Square, San Francisco, CA (2003)

• New York Presbyterian Hospital, New York, NY

• UMass Medical School, Worcester, MA (2004)

• Seattle Justice Center, Seattle, WA (2002)

• Yazaki North American, Canton, MI (2000)

ARUP Offi ces, London

Victoria House, Cologne

3’-0” Multi-story fl ue with fi xed sunshades in the cavity:

• Occidental Chemical Building, Niagra Falls, NY (1982)

3’-0” Deep Corridor Style: Airfl ow contained to single story

• Genzyme Center, Cambridge, MA (2003)

• University of Michigan Biomedical Science Research Building

• Art Institute of Chicago - Modern Wing, Chicago, IL (2009)

• Cleveland Art Gallery, Cleveland OH (2009)

Narrow +/- 8” deep System:

• Manulife Financial, Boston, MA (2003)

TYPOLOGIES OF DOUBLE-SKIN FACADES IN THE UNITED STATES: To date, approximately 12 major double skin facades in a variety of confi gurations have been constructed:

FABRICATION AND ENGINEERING BY LEADING EXPERTS IN EUROPEAN DOUBLE SKIN TECHNOLOGY

Victoria Ensemble, High Rise - type 1

3. Other projects visited by design team (continued):

Victoria Ensemble, Low rise - type 2

Winter Air Flow

1

2

3

2

1 Closed louvers shield from low angled sun glare into building

2 Closed top and bottom vents trap air inside double skin cavity

3 Air within cavity heats up, effectively creating thermal barrier between external and internal environments

Outer skin

Inner skin

Exhaust vent with operable glass louvers

Operable windows

Operable aluminum louvers

Glass visors

Intake trench with operable damper

Structural ladder frame

Glass visors

Operable windows

Operable aluminum louvers

Bay Detail

Spring/Fall Air Flow

1 Upper and lower vents can be opened or closed to modulate temperature of cavity

2 Operable windows allow natural ventilation

2

2

1

1

Summer Air Flow

1 High angled sun is caught by horizontal louvers, heating the double skin cavity and providing shade to building

2 Cooler air is drawn into double skin cavity through open lower vents

3,4 Air heats up and rises within cavity, creating chimney effect and drawing hot air away from building mass

1

2

3

4

Double-skin cavity, catwalk for window cleaning

Aluminum louvers, adjustable to two positions

Louvers adjust to low sun angle

12

34

5

6

7

Double Skin Components

1 Exterior Glazing2 Interior Glazing3 Structural Frame

4 Operable Sun Shade5 Sun Shade Canopy

6 Lower Operable Ventilation7 Upper Operable Ventilation

SHADING ELEMENTS VENTILATION ELEMENTS

8

8 Maintenance Catwalks

Structural ladder frame Inner glass skin installed

Structural ladder frame Outer glass skin installed

Glass visor installationStructural ladder frame erection

A Unique High-Performance Facade: The double-skin facade (two surfaces of glass, creating an insulated airspace) is a multi-story (full height), full depth (3’), thermal fl ue. The facade allows for complete transparency while ensuring protection from excessive heat gain, heat loss, and glare:

Energy Savings and Comfort: The facade saves energy (50 % reduction compared with a conventional curtainwall) and maximizes comfort at the reading spaces. The 3’ airspace can be open in summer to keep heat from entering the building and closed in the winter to create an insulating “thermal blanket;”

Natural Light:The facade brings a signifi cant amount of balanced natural light into the library, carefully controlled by fi xed and movable sunshades.

Natural Ventilation: Operable windows in the facade allow for fresh air throughout the year (even in winter) without insect screens blocking and without concern for stolen books. In the winter, spring and fall, the windows allow heat from the cavity to be brought into the building.

A Pioneer of Advanced Sustainable Design Technology: The First Double Skin Facade on a US Public Library, the project is also the fi rst US Project to incorporate three key ingredients of European Double-skin curtainwall technology:

•3’-0” Deep Airspace

•Multi-story Thermal Flue

•Movable 1’-0” Deep Sunshades

COMPLETION DATEFall 2009

DESIGN TEAM:William Rawn Associates, ArchitectAnn Beha Architects, Architect for historic buildingMichael Van Valkenburgh, Landscape ArchitectOve Arup Facade Engineering, Curtainwall consultantConsigli JF/ White, General ContractorJosef Gartner GmbH, Curtainwall fabricatorLeMessurier Consulting Engineers, Structural engineerVanderweil Engineers, MEP, FP engineers

PROJECT FACTS:

SIZE104,000 SF

76,800 SF New building27,200 SF Historic building (Van Brunt & Howe, 1889)70 space parking garage

OWNERCity of CambridgeCambridge Public Library

Susan Flannery, Director of Libraries, City of CambridgeAlan Burne, Project Director, City of Cambridge

William Rawn Associates, Architects, Inc.10 Post Offi ce Square, Suite 1010, Boston, MA 02109t) 617.423.3470 f) 617.451.9205 www.rawnarch.com

DOUBLE-SKIN FACADE