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Calgary || Canada
The Bow, a 237- metre-high headquarters tower – is the city’s tallest building and Canada’s tallest tower outside Toronto. A bold new landmark on the skyline, the project is equally significant in urban, social and environmental terms: the public base of the tower is filled with shops, restaurants and cafes and extends into a generous landscaped plaza, while the office floors are punctuated by three six-storey sky gardens, which encourage natural ventilation and help to significantly reduce energy use. The Bow is the first major development on the east side of Centre Street, a major axis through downtown Calgary, and it provides a shared headquarters for Encana and Cenovus.
The building’s form was shaped by analysis of the climate and organisations. The tower faces south, curving towards the sun to take advantage of daylight and heat, while maximising the perimeter for cellular offices with views of the Rocky Mountains. By turning the convex facade into the prevailing wind, the structural loading is minimised, thus reducing the amount of steel required for the inherently efficient diagrid system. Each triangulated section of the structure spans six storeys, helping to visually break down the scale of the building. Where the building curves inwards, the glazed facade is pulled forward to create a series of atria that run the full height of the tower.
These spaces act as climatic buffer zones, insulating the building and helping to significantly reduce energy consumption. As each floor plate has been sized to accommodate a whole business unit, there was a need to promote collaboration across the companies and bring a social dimension to the office spaces. Vertical access to the office floors is therefore directed through three spectacular sky gardens, which project into the atria at levels 24, 42 and 54 and incorporate mature trees, seating, meeting rooms, catering facilities and local lift cores. Staff facilities in these atria are complemented by an auditorium at the very top of the building.
The Bow also establishes lateral connections with surrounding buildings. The tower is fused at two points to Calgary’s system of enclosed walkways, which offers a retreat from the city’s harsh winters. The second floor is open to the public and integrates shops and cafes, and with the only public connection over Centre Street, the scheme completes a vital pedestrian link in the downtown network. Externally, the building’s arc defines a large landscaped public plaza, at the heart of which is a landmark sculpture by Spanish artist, Jaume Plensa.
Location: Calgary, Canada
Client: H+R Real Estate Investment Trust
Gross Floor Area: 199.800 m2
Architects: Foster + Partners
Design Team: Norman Foster, David Nelson, Spencer de Grey, Nigel Dancey,James Barnes, Julia Vidal Alvarez, Laura Alvey, Tim Bauerfeind, Jakob Beer, Karin Bergmann, Mattias Bertelmann, Stephen Best, Federico Bixio, Marie Christoffersen, Vasco Correia, Kirsten Davis, Ulrich Hamman, Michelle Johnson, Arjun Kaicker, Sabine Kellerhoff, Chiu-Ming Benny Lee, Mathieu Le Sueur, Shirley Shee Ying Leung, Alissa MacInnes, Carsten Mundle, Florian Oelschlager, Cristina Perez, Susanne Reiher, Diana Schaffrannek, Anja Schuppan, Carolin Senfleben, Robert Smith, Eva Tzivanki
Collaborating Architect: Zeidler Partnership
Artist: Jaume Plensa
Main Contractor: Ledcor Construction
Civil Engineer: Kellam Berg
Mechanical : Cosentini
Fire: Leber Rubes
Vertical Transport: KJA
Cost: Altus Helier
Lighting: Claude Engle Lighting Design
Landscape: Carson McCulloch
Planning: Sturgess Architecture
Wind Engineer: RWDI
Transportation Engineer: DA Watt
Art: Via Partnership
Cladding: Brook Van Dalen
Photography: © Nigel Young_Foster + Partners