Green Design at Evergreen Brick Works: Building Envelope
Background image: Tom Arban
The building envelope at Evergreen Brick Works—its walls, insulation, facade and windows—is airtight, highly insulated and built to last, resulting in 34% annual energy savings and a 14-tonne reduction in CO2 emissions.
Built to Endure
In general, longer-lasting buildings will have a smaller impact on the environment in terms of embodied energy and carbon footprint. Costly repairs to improperly designed buildings can increase embodied energy costs and overall impact.
A building’s durability is determined by the quality of its materials, products and construction and ongoing inspection at every stage of the way.
The walls combine 15 centimetres of locally manufactured rigid mineral wool placed to the exterior of the building sheathing. An additional five centimetres of closed-cell foam is placed in a steel cavity inside the building.
Typical office buildings have R-values in the R-7 to R-10 range. These walls achieve a total R-value of R-35, and the roof is R-50. Additional insulation to the exterior of the roof along with 15 centimetres of growing medium further reduces the need for energy to heat and cool the building.
Cladding and Screening
Rather than aluminum, we chose steel that is manufactured and recycled with a lower carbon footprint. The cladding is corrugated and covered in zinc to extend its life. It is 80% post-consumer and 16% pre-consumer recycled content, and 100% regionally manufactured.
In future phases, movable perforated metal screens on the west and south faces will further reduce heat gain. In addition to reducing energy required for cooling, this screening will also function as a canvas for artwork.
Green and White Roof
Roofing materials reflect light away from the building and three green roofs on the lower and upper levels of the 5th floor help cool the building. The 3,000-square-foot green roof is used by staff to observe how different plants perform on roofs.
Planted with grasses and wildflowers native to the region, the green roof on the Centre for Green Cities building provides wildlife habitat, storm water retention, space for urban agriculture, and insulation against heat and cold.
A building is most vulnerable to being energy inefficient via its windows. The all-glass exteriors of many modern office buildings lose heat in winter and trap it inside in summer.
In contrast, windows make up only 22% of the Centre for Green Cities’ building envelope. Their placement ensures that west-facing windows minimize solar heat gain, while those on the east side maximize it. Manually operated windows and blinds allow the occupants to control ventilation, heat and glare.
Durable fibreglass frames insulate better than metal, and resist the thermal expansion and contraction that can compromise seals. It also requires the lowest amount of energy to produce when compared to other window- frame materials, such as aluminum.
All windows are double-glazed, with a layer of Heat Mirror, a transparent film which reflects radiated heat, suspended between the panes. Combined, these provide an insulation value of R-8, compared to R-3 or lower in a typical condominium building.
The Centre for Green Cities building re-uses the original walls from a one-storey structure known simply as Building 12, a storage area and woodworking shop originally constructed in 1961.
The new foundations rest on steel micropiles, drilled into the ground rather than pounded in. This displaces as little earth as possible, an important consideration on a brownfield site with known soil contamination. It also limits any vibrations that could damage the heritage buildings on-site and disturb neighbouring residential areas.
Frame and Floors
For a lightweight structure with a low carbon footprint, we used a steel frame and precast plank floors. A structural dome flooring system made from recycled plastic creates a self-supporting structure that replaces truckloads of aggregates.
Hollow cores within the concrete planks provide channels for the delivery of air, power and data services.
The prefabricated steel columns are manufactured locally, reducing the energy required for transport. The steel is 26.9% post-consumer and 36.1% pre-consumer recycled.