A plan for a Government of Canada Building was put into place in 2002 to improve the delivery of services to communities in the Northwest Territories and is a positive addition to Yellowknife City’s downtown core. Using LEED® guidelines, the building provides healthy and energy-efficient components that align with a typical Yellowknife commercial building construction budget. Williams Engineering (WE) provided structural and mechanical engineering design services for the first North of 60 LEED® Canada-Gold certified office building.
The Greenstone Building design takes the severe climate into account, and it was designed to be durable and flexible while accommodating the needs of the various departments that will occupy it over the planned 75-year life expectancy.
Design objectives were understandably complex in order to meet the needs of the client for this 6,800 m2, four-storey office building. The reinforced concrete flat slab structural system is a unique feature of Yellowknife. Fall arrest systems were designed for the roof and interior elevated walkways to provide a safe working environment for maintenance staff. Roof design loads exceeded floor loads due to the installation of a plant-growing medium (green roof) and the placement of mechanical equipment.
Increased levels of fly ash were used in the concrete design mixes to meet the LEED® requirements of this project. Unique structural designs included a parallel flat plate structure for the main entrance canopy, a structural steel sunshade to provide the building occupants with protection from direct sunlight, and a custom balustrade design.
The mechanical designs were both cost-effective and forward-thinking for a reduction of energy consumption by 35% over ASHRAE 90-1. The building has been fitted with a unique Underfloor Air Distribution System (UFAD). Occupancy sensors shut off ventilation air when not required, and all washrooms use ultra-low volume fixtures and no flush urinals for a 35% water consumption reduction over standard fixtures. A rainwater recovery system was designed to provide water to the water closets.
The design philosophy was to showcase the best available environmental practices, minimize the impact of the building on the natural environment, and to demonstrate practical high-performance building strategies.