International architecture firm Snøhetta and Canada's Dialog drew inspiration from local Chinook cloud arch formations when designing Canada's Calgary Central Library. The building is situated in a very challenging plot that incorporates an existing light rail track and wows visitors with an eye-catching timber-lined atrium.

The Calgary Central Library (aka Calgary New Central Library) features an energy-efficient triple-glazed facade that comprises a hexagonal pattern of fritted glass and aluminum panels. The pattern brings to mind snowflakes, which seems apt considering the city's harsh winters.

Visitors enter the main atrium by passing through a large wood archway inspired by the Chinook cloud arch. The atrium itself is stunning and defined by a double-curved shell created from planks of western red cedar sourced from British Columbia. It's topped by a decorative oculus and is designed to help visitors orient themselves in the 240,000 sq ft (22,300 sq m) building.

"Wood slats line the perimeter of the open atrium, shaped in plan like a pointed ellipse, serving as an orientation device for people to quickly grasp the circulation and organizational logic of the library," says Snøhetta. "Inside, the concrete structure is left exposed and unfinished, hinting at the open-ended possibilities within."

The material palette is a simple mixture of wood, glass and concrete. It looks superbly done, with the glazed facade ensuring lots of natural light inside. The floorplan of the building is laid out so that louder public activities are carried out on the lower floors and quieter study areas are tucked away on the upper floors. The library also includes a children's area with playhouses, books and activities.

The northernmost point of the library, meanwhile, hosts a cafe overlooking the light rail track. Visitors can sip their drinks while watching trains pass below.

Snøhetta is certainly no stranger to challenging projects, but designing a library atop a rail track does seem fraught with potential issues, including noise and vibrations inside the library.

"To mitigate structural vibrations, the LRT [light rail track] encapsulation was constructed as a structurally-separate 'shell' such that no new grade beams or walls would touch the existing Calgary Transit infrastructure; a physical de-coupling of the structural systems," explains the team to New Atlas.

"Acoustic filler material was placed between the existing trench walls and the new grade beams and transfer pile caps supporting the library columns above. The terraced floor above the roof of the encapsulation was built on a thick layer of structural foam blocks. Interior walls were built with a large air gap between them and the encapsulation walls.

"Any acoustically-sensitive rooms near to the LRT were structurally isolated using box-in-box construction (specifically the theater, and ground-level multipurpose rooms). These physical strategies were enhanced by the fact that the library program does not require absolute silence. Activity and movement in the space is seen as a benefit to the overall experience of the library, so that relatively small vibrations from the LRT would generally not be audible.

"Organized on a spectrum of 'Fun' to 'Serious,' the organizational logic of the library program locates the livelier public activities on the lower floors, which responds directly to the site's acoustic constraints. Any spaces that do require a higher degree of acoustic privacy (i.e Great Reading Room, sound recording studios) are located at the uppermost levels of the building, at which point any vibrations or air-borne sound from the LRT would have dissipated to an acceptable level."

"An additional note on how the management of the interior acoustics responds to the building's siting over the LRT: the rhythm of the concrete structure echoes the curving path of the LRT below throughout each of the four floors of the building," continues the team. "Between the structural beams are fabric-covered acoustic baffles, which provide acoustic absorption that is carefully calibrated for each space."

Calgary Central Library's design was chosen back in 2013 following an architectural competition and the total cost for the project came in at CAD 245 million (roughly US$187 million).

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