By Silvio Baldassarra, OAA, FRAIC
Green, patinated copper is the result of a natural aging process and has been coveted by architects and designers since ancient times. Copper does not react with water, but it does with atmospheric oxygen, forming a layer of brown-black copper oxide protecting the underlying metal. The cherished green layer of verdigris (copper carbonate [CO2CO3]) varies depending on the amount of sulfur in the local atmosphere. This natural process takes years but stabilizes to form a distinctive green patina, forever sealing and protecting the raw copper.
As executive architect for 180 Wellington St., Ottawa, the author wanted to save the copper material removed from the roof of a 1920s office building and reuse it to line the walls of a library in the building. However, the challenge was to develop a design for reusing the sheet material in an innovative manner, while resolving the library’s sound attenuation challenge. There was also a technical issue related to oil canning (deformation of thin metal sheets).
The Wellington Building underwent rehabilitation from 2010 to 2016. Situated across from Parliament Hill, the Beaux-Arts style structure now contains office suites for Members of Parliament (MPs) and committee rooms, as well as a satellite location of the Library of Parliament. The library, located in a double-height, skylit space, is reserved for the use of MPs and their staff.
An early design idea was to simply use the sheet copper material on the walls of the library. While this is not a novel approach given the application, it would have been a dramatic installation. However, the idea was rejected by the client, citing the opinion copper is “not a noble material to be used for interior finishes.” NORR Architects and Engineers believed reuse of the existing green, patinated copper to line the library was the right solution, and worked to create a design execution that would satisfy the client’s standard of a “noble” finish.
The second and final solution was technical, esthetic, and sustainable. The plan was to create a floating, sculptural copper shell in front of a perforated, precisely bent, modulated copper lining to the wall. The shells are reflective of the triangulated shapes of the roofscape of Parliament Hill. A total of 3500 floating, sculptural copper shells were envisioned, driven by the 406-mm (16-in.) width of the recycled copper material.
NORR worked with F.M. Enterprises, a copper roofing specialist, to create a full-scale prototype of the copper panel concept. The final design and completed panels were created by NORR in co-operation with Mometal Structures; EllisDon Constructors acted as construction managers.
The copper shell grid and perforated panels provide a sculptural finish to the four walls of the library. The skylight above the entire room brings the floating shells to life throughout the day as natural light moves from east to west, changing the shadows through the seasons. At night, artificial light supplements and eventually takes over with even distribution. The combination of natural and artificial light on the copper shells offers the room a dynamic, sculptural wall treatment.