Vancouver, British Columbia — Located in one of West Vancouver’s most exclusive communities, Pacific Arbour Retirement Communities’ (PARC) Westerleigh Retirement Residence sets new standards in senior living as well as sustainable design. The seven-story facility features a green roof with drought-tolerant vegetation, reduced use of potable water, innovative heat recovery strategies, and structural thermal breaks as strategies that helped achieve LEED Gold certification.
“We own and maintain this facility, so we wanted it to be comfortable, sustainable and efficient,” explains PARC vice president of Development and Construction, Russell Hobbs.
The 13,020 sq m (140,000 sq ft) facility contains 129 rental suites, more than 100 of which access balconies that wrap around the south and west sides of all seven floors.
“The continuous six-foot-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.”
To prevent the balconies from conducting heat from interior floor slabs into the exterior environment, they are thermally broken where they penetrate the building envelope using Isokorb® structural thermal breaks. "Without them, there would be quite a lot of exposed slab and thermal bridging,” Friars continues.
Thermal bridging occurs where balconies, canopies, slab edges, parapets, rooftop equipment supports and other structures penetrate the building envelope. Like cooling fins, these penetrations draw heat from interior concrete and structural steel through the insulated building envelope, dissipating it into the exterior environment. In addition to wasting energy and emitting carbon, chilling the interior side of structural penetrations can cause condensation and mould to form on adjacent interior surfaces of today's air-tight, high-humidity buildings, exposing the developer to remediation and liability risk.
Tenant comfort is also compromised when uninsulated balconies chill interior floor slabs — an issue of particular significance in residences for seniors.
Isokorb® products for concrete construction create a thermal break between the interior slab and balcony. Stainless steel rebar projecting from one side of the thermal break is cast into the interior floor slab while stainless steel rebar projecting from the opposite side is cast into the cantilevered balcony, providing load-bearing support equivalent to that of monolithic balcony extensions of interior floor slabs.
Schöck North America claims that structural thermal breaks reduce heat loss at balcony penetrations by up to 90 percent. At Westerleigh, some 900 Isokorb® assemblies were installed. With a width of 914 mm (36 in) each, that makes for 810 m (2,700 ft), or more than a half of a mile of thermal breaks, and a big factor in achieving LEED Gold, says Westerleigh Director of Construction, Bob Fritz.
“We had already cut our teeth on thermal breaks from design to installation at our 11-story Cedar Springs Retirement Residence in North Vancouver,” adds Westerleigh chief engineer, Levi Stoelting, principal at Glotman Simpson. The projects had differences, however. The deep, continuous balconies at Westerleigh have a different loading configuration than for the eyebrows (smaller shade-producing concrete slabs) installed at Cedar Springs. Also at Westerleigh, “We had to figure out how to incorporate the modules into the fire separation and the cladding line and work those together with waterproofing and sound transmission elements. The product can accommodate this,” Stoelting says.
“The thermal breaks for Westerleigh were designed in conjunction with our structural engineer and architect,” says Russell Hobbs. “Because of the different loading configuration for the balconies, our engineers began working with Schöck eight months before construction to design them specifically to the project.”
Based on the success with these two projects, PARC Living also installed Isokorb® thermal breaks on its Oceana PARC retirement residence in White Rock, BC, which was completed in 2019.
According to Project Building Envelope Consultant Sophie Mercier, Director of Building Science West at Morrison Hershfield engineers, structural thermal breaks also provided the flexibility to incorporate other energy saving measures. “With thermal breaks improving the efficiency of the building envelope, you can use a smaller, less complicated mechanical heating system,” she explains. “For example, you can use electric baseboard heating, which gives you clean energy and a simple mechanical system. And simpler systems are less costly in the long term. That’s the benefit of having a thermally-efficient envelope.”
While the adoption of structural thermal breaks throughout North America has been exponential since the completion of the Westerleigh project in 2013, it has also been largely discretionary. Canadian provinces and local jurisdictions, as in the United States, adopt the national building code on varying schedules, depending on local climatic, economic, cultural and political variables. Vancouver has adopted higher standards than in most U.S. and Canadian jurisdictions.
Increased awareness of structural thermal breaks among developers, architects, engineers, governments and code officials charged with cutting energy use and carbon emissions is driving many North American regions to make them a code requirement, as it has been for many years throughout Europe.
“People are seeing a better-performing building because of thermal breaks, and they should become the industry standard,” adds Stoelting. “Their use is going to become more common because the code is driving us in that direction. We’ve used them on a mental health facility, a hospital, and a number of residential projects, and have recommended them on other projects that are in active design. They are a very good tool in our arsenal.”
thermal breaks for balconies
BFA Studio Architects
Ventana Construction Corporation