Source: Web page  Canadian Consulting Engineer (www.canadianconsultingengineer.com/)
Though not classed as a tall building, an eight-storey high-rise in downtown Vancouver points to new directions in the design of their curtain walls. In rehabilitating the 1940s section of the Telus William Farrell Building along Robson Street, the designers added a second skin of glass outside the original walls to create a buffer layer. This "plenum" acts as an insulating layer to reduce energy consumption and has operable windows to let the occupants enjoy fresh air. (See also the double-wall construction used in one of the world's largest and most innovative "green" towers -- the Commerzbank in Frankfurt (CCE January-February 1999).
The building's new exterior glass skin is suspended one metre away from the existing building face. Motorized dampers and photovoltaic powered fans assist in moving the air up and out of the plenum when necessary and work in tandem with the operable windows. The exterior glazing is a combination of fritted glass panels to reduce solar gain, combined with clear glass that allows the occupants to see outside. Light shelves are also installed above the existing windows to help daylight penetrate inside the building. After running simulations, Keen found that single glazed existing windows and a double-glazed plenum skin was the best solution in order to avoid condensation.
The energy upgrade included installing raised access flooring with underfloor air plenums, new lighting and fire protection. The primary heat source is an existing refrigeration plant. Its rejected heat is captured and redistributed.
Projected to use 65% of the consumption levels set by the Vancouver Energy by-law, the project won an energy efficiency award from Natural Resources Canada last year and represented Canada in the 2000 Green Building Challenge held in the Netherlands. | 