The importance of structural thermal breaks
Pacific Arbour Retirement Communities (PARC), which operates several senior residences in British Columbia, has incorporated structural thermal breaks in five buildings to avoid thermal bridging at balconies, rooftop connections, and canopies, which also contributes to the requirements for achieving LEED gold certification.
Constructing senior residences for sustainability, PARC targeted 25 per cent in energy savings at its Cedar Springs location through design elements such as an insulated exterior wall system, shade-producing eyebrows, triple-glazed windows, and structural thermal breaks.
“If we design something that’s efficient from a utilities-usage standpoint, that’s always helpful to us from an investment perspective,” says PARC vice-president of development and construction, Russell Hobbs. “Long-term efficiencies are a big consideration for us.”
Using structural thermal breaks to reduce heat loss contributed to the building’s overall efficiency, creating more comfortable and consistent interior floor temperatures while using a smaller, less expensive heating system.
Going green adds to occupant comfort
Located in one of West Vancouver, B.C.’s most exclusive communities, PARC’s Westerleigh Retirement Residence is a seven-storey facility that incorporates a green roof with drought-tolerant vegetation, reduced use of potable water, and innovative heat recovery strategies which helped it to achieve LEED gold certification.
The 13,020 m2 (140,000 sf) facility contains 129 rental suites, more than 100 of which have access to balconies that wrap around the south and west sides of all seven floors.
“The continuous 1.8-m (6-ft)-deep balconies wrap around the bottom four floors of the building and then step back on floors five through seven, which are smaller,” explains project architect Shane Friars, principal at BFA Studio Architects. “In addition to providing amenity space, they shade the south and west sides of the building.”
As with Cedar Springs, to prevent the balconies from conducting heat from interior floor slabs into the exterior environment, structural thermal breaks were installed at the point of penetration through the building envelope.
“Without them, there would be quite a lot of exposed slab and thermal bridging,” says Friars. “Tenant comfort is compromised when uninsulated balconies chill interior floor slabs—an issue of particular significance in residences for seniors.”
Sustainable, urban design
Another PARC facility, the Oceana, is located in metro Vancouver, B.C. As with other PARC properties, Oceana’s energy-saving measures include a green roof with drought-tolerant vegetation, and a robust building envelope of 152.4 mm (6 in.), semi-rigid stone wool insulation on the exterior, and 88.9 mm (3.5 in.) fibreglass batt insulation inside of the wall.
Other energy-saving measures include heat recovery ventilators, rooftop high-efficiency boilers feeding hot water storage tanks, a hot water recirculation system, and exclusive use of LED lighting.
Out of Oceana PARC’s 199 residential living units, 181 include balconies, which are insulated using structural thermal breaks in the same manner as the Cedar Springs PARC and Westerleigh PARC balconies. However, Oceana PARC presented additional thermal bridging concerns at its parapets, which was mitigated by installing structural thermal breaks engineered for concrete parapet-to-roof-slab connections.
The conventional method to reduce heat loss through parapets is to wrap them with an insulation barrier. However, wrappings are prone to damage and water penetration over time, particularly where railings, covers, or fasteners pierce the insulation, requiring repair and maintenance.
