United Nations Secretariat Building Download PDF


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Height: Occupied
140.8 m / 462 ft
 
Height: To Tip
154.3 m / 506 ft
Height: Architectural
154.3 m / 506 ft
 
United Nations Secretariat Building Outline
Floors Above Ground
39
Floors Below Ground
3
# of Elevators
20
Top Elevator Speed
6.1 m/s
Tower GFA
82,272 m² / 885,568 ft²

Facts

Official Name United Nations Secretariat Building
Other Names UN Headquarters, U.N. Building
Structure Type Building
Status Completed
Country United States
City New York City
Street Address & Map 750 1st Avenue
Postal Code 10017
Building Function office
Structural Material steel
Construction Start 1947
Completion 1953
Retrofit Start 2010
Retrofit End 2013

Original Companies Involved

Owner
• Current United Nations
Developer William Zeckendorf
Architect
Design Le Corbusier; Oscar Niemeyer; Wallace K. Harrison

Retrofit Companies Involved

Owner
• Current United Nations
Architect
Design Heintges & Associates; HLW International
Structural Engineer
Design HLW International
Project Manager Gardiner & Theobald Inc
Main Contractor Skanska
Other Consultant
• Acoustics Shen Milsom Wilke, Inc.
• Code Rolf Jensen & Associates
Façade Heintges & Associates
• Fire Rolf Jensen & Associates
• Interiors HLW International
• Landscape di Domenico + Partners, LLP
• Lighting HLW International
• Security Kroll Inc; Weidlinger Associates
• Sustainability HLW International; Viridian Energy & Environmental, LLC

About United Nations Secretariat Building

The Secretariat tower is arguably the most visible representation of postwar optimism and resiliency on the United Nations campus. It also embodies a mid-century Modernist merging of technology and form, as expressed in the remarkably slim north-south facing profiles and the crystalline east-west elevations.

When the multi-billion dollar renovation of the UN campus started, the Secretariat, which has never ceased to operate as a functional government building, was plagued by severely outdated fixtures, deficient life safety features, and a leaky curtain wall. It is estimated that the historic building had operated at least 35 years past its normal lifespan.

Key design strategies for increasing performance included the extensive redevelopment of the base building core and systems, including new elevator systems and mechanical infrastructure, new fire protection systems and code upgrades, disabled-access compliance, and asbestos abatement. Floor plate utilization was enhanced through the introduction of a new planning diagram. It also involved installing a better, more efficient envelope for insulation and blast protection.

The Secretariat was the first tall building to employ a suspended wall system. Its primary elevations were enclosed by free-hanging glazed facades. The new curtain wall was designed to look like it did when it first opened—sleek and taut, with its double-hung aluminum windows, glazed spandrel panels, and aluminum-clad steel mullions appearing as one continuous transparent form. The replaced wall’s appearance had been significantly altered after nearly 60 years of patches, caulkings, insulating and blast coatings, resulting in a patchwork appearance and a greenish hue.

To rectify this, the project team conducted extensive testing to replicate the visual appearance of the original building, including reflection patterns at different times of day. The work included spectral analysis of glass types to identify viable formulas, computer model simulation, and, ultimately, a full-scale mockup tested on the UN grounds.

The original curtain wall was demolished and replaced with a pressure-equalized system in sections, proceeding from bottom to top in each 10-story zone between the louvered mechanical levels. Unlike the original curtain wall, which had been attached to the concrete floor slabs, the new system is connected to the now-reinforced building frame via outrigger plates. To mimic the appearance of the original double-hung windows, the team strategically offset some of the aluminum extrusions. The new cladding incorporates performance enhancements, such as low-E coating and blast protection.

The new open floor plan challenges the closed culture propagated by the original cellular offices. Significantly more light and air now enter the interior. The open plan also affords more flexibility and efficient use of space in a rapidly growing organization; the Secretariat now serves 193 member-states, as compared to the original 50.

The open-plan daylighting scheme includes 1,981-millimeter-tall furniture-work walls that extend from perimeter columns, without blocking natural light. The ceiling is 2.4 meters high but gradually steps up to 2.9 meters at the windows, allowing for a circulation path around the core, while supporting the equitable distribution of mechanical services. Seventy-five percent of workspaces now have daylighting and views.

Overall, the resulting building is 50 percent more energy-efficient than it was before the renovation. Replacement was never an option due to the iconic nature of the tower; instead, the classic building was thoroughly renovated in place. In many ways, the Secretariat’s radical revitalization is more about rebirth than restoration.

CTBUH Initiatives

United Nations Secretariat Building Renovation Tour
28 Oct 2015 – Tour Report

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Videos

United Nations Secretariat: Renovation of a Modernist Icon
26 Oct 2015 – Michael Adlerstein, United Nations Capital Master Plan

Interview: Michael Adlerstein
26 Oct 2015 – Michael Adlerstein, United Nations Capital Master Plan

2014 Awards - Session 1 Q&A
6 Nov 2014 – Chair: Jeanne Gang, Studio Gang

More Videos

Videos Related to United Nations Secretariat Building

Videos Related to United Nations Secretariat Building

United Nations Secretariat: Renovation of a Modernist Icon
26 Oct 2015 – Presentation at CTBUH 2015 New York Conference; Michael Adlerstein, United Nations Capital Master Plan
Michael Adlerstein shares his insights into how the United Nations Secretariat Building, an aging icon of Mid-century Modernism, was renovated to meet the security,…
Interview: Michael Adlerstein
26 Oct 2015 – 2015 New York Conference Interviews; Michael Adlerstein, United Nations Capital Master Plan
Michael Adlerstein of United Nations Capital Master Plan is interviewed by Chris Bentley during the 2015 CTBUH New York Conference at the Grand Hyatt New York. Michael…
2014 Awards - Session 1 Q&A
6 Nov 2014 – CTBUH "13th Annual Awards"; Chair: Jeanne Gang, Studio Gang
Dr. Peter Irwin, Founding Partner, RWDI Consulting Engineers, Michael Adlerstein, Assistant Secretary-General & Executive Director, United Nations Capital Master Plan,…
Best Tall Building Featured Finalist: Modernist Optimism Reconfigured for a New Century: The UN Secretariat
6 Nov 2014 – CTBUH "13th Annual Awards"; Michael Adlerstein, United Nations Capital Master Plan; John Gering, HLW International
When the multi-billion dollar renovation of the UN campus started, the Secretariat, which has never ceased to operate as a functional government building, was plagued by…
Interview: U.N. Secretariat Building Retrofit
6 Nov 2014 – 2014 Awards Ceremony/Symposium Interviews; Michael Adlerstein, United Nations Capital Master Plan; John Gering, HLW International
Thursday, 6th November 2014. Chicago, USA. Michael Adlerstein, United Nations Capital Master Plan & John Gering, HLW International, discuss the retrofit of the United…
Monthly Video: U.N. Secretariat Building Retrofit
6 Nov 2014 – Monthly Video Series; Michael Adlerstein, United Nations Capital Master Plan; John Gering, HLW International
Thursday, 6th November 2014. Chicago, USA. Michael Adlerstein, United Nations Capital Master Plan & John Gering, HLW International, discuss the retrofit of the United…
New Skins for Skyscrapers: Anticipating Façade Retrofit
19 Sep 2012 – Presentation at CTBUH 2012 9th World Congress, Shanghai; Mic Patterson, Strategic Development Director, Enclos
The existing building stock in some regions accounts for nearly as much energy consumption and carbon emissions as the transportation and industrial sectors combined.…

Browse hundreds of other videos from Council events including conferences and interviews with prominent tall building professionals in the Video Library

Research Papers

United Nations Secretariat: Renovation of a Modernist Icon
26 Oct 2015 – Global Interchanges: Resurgence of the Skyscraper City

CTBUH Awards

Best Tall Building Americas 2014 Finalist
CTBUH Awards 2014


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