White Rock, British Columbia — On the Johnston Road Corridor in the city of White Rock (Metro Vancouver area), PARC Retirement Living is employing the latest in building envelope technology and sustainable design throughout its Oceana PARC residence.
PARC Director of Construction Bob Fritz says, “We’re an owner/operator, so energy efficiency is very important to us, not only for our residents’ comfort, but also because of lower operating costs, lower heating and cooling bills.”
As with two of PARC Retirement Livings’s other Vancouver area retirement residences, Cedar Springs PARC and Westerleigh PARC, Oceana PARC’s energy-saving measures include a green roof with drought-tolerant vegetation, and a robust building envelope of 6 in. (15 cm) semi-rigid stone wool insulation on the exterior and 3½ in. (9 cm) fiberglass batt insulation inside of the wall. The building envelope also incorporates 5,970 linear feet (1,820 m) of Isokorb® structural thermal breaks to significantly reduce energy loss at the balconies.
Additional energy-saving measures at Oceana PARC include heat recovery ventilators, rooftop high-efficiency boilers feeding hot water storage tanks, a hot water recirculation system, exclusive use of LED lighting and — a first in the Metro Vancouver area — concrete parapets insulated from the heated building interior using structural thermal breaks.
Thermal bridges occur where balconies, parapets, canopies, rooftop equipment and other structural elements penetrate the building envelope. Like cooling fins, these penetrations draw heat from interior concrete and structural steel through the insulated envelope, dissipating it into the exterior. In addition to increasing energy use, carbon emissions and costs, thermal bridges chill the interior side of structural penetrations. This creates an environment for condensation and mold growth, and results in uncomfortably cold floors adjacent to balconies — an issue of particular significance for retirement residences.
Of Oceana PARC’s 199 residential living units, 181 include balconies, which are insulated using Isokorb® 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 the PARC team mitigated by installing new Isokorb® structural thermal breaks engineered for concrete parapet-to-roof-slab connections.
Supplied by Schöck North America, the structural thermal break modules are comprised of a longitudinal block of foam insulation traversed by rebar to be cast into the slab on one side and the balcony or parapet on the other, providing load-bearing support equivalent to that of monolithic extensions of floor and roof slabs. The rebar crossing the foam insulation is made of stainless steel for superior corrosion resistance compared to carbon steel rebar.
Independent third party testing shows that Schöck's concrete-to-concrete structural thermal breaks reduce heat energy loss at envelope penetrations by up to 90 percent, and up to 14 percent for the building overall depending on the number of balconies, length of balconies/parapets and other variables.
"On Cedar Springs and Westerleigh retirement residences, we installed Isokorb thermal breaks in the slabs at the balconies and eyebrows," says Fritz. "In these buildings we didn’t have conditions where we had upstand parapets. But while working on the Oceana PARC design, Schöck told us about a new thermal break product that specifically deals with thermal bridging at parapet upstands. And we have quite a lot of parapets on this project. So, we incorporated those thermal breaks as well.”
Two buildings comprise the Oceana PARC complex — a 23-story tower main building and a two-story auxiliary building. Containing 199 residential units, the tower building provides approximately 202,800 sq ft (18,841 sq m) of gross floor area. The two-story auxiliary building adds another 8,600 sq ft (780 sq m) of gross floor area, and connects to the main building by an enclosed bridge. Also included is a 2-level underground parking garage totaling 68,500 sq ft (6370 sq m).
Parapets occur at the perimeters of levels two and three in the auxiliary building and at the roof level of the main tower for a combined 1,100 linear feet (335 m), so thermal bridging needed to be avoided.
The conventional method to reduce thermal bridging through parapets is to wrap them with an insulation barrier. However, wrappings are prone to damage and water penetration, particularly where railings, covers or fasteners pierce the insulation, requiring repair and maintenance.
Whereas parapets wrapped with insulation barriers remain part of the heated building mass, parapets insulated and supported by structural thermal breaks sit outside of the heated building envelope above roof slab, retaining heat energy more efficiently, while supporting loads equivalent to monolithic parapet structures.
The Isokorb® module is a longitudinal assembly fabricated to the same width as the parapet.
Graphite-enhanced expanded polystyrene insulation is placed between stainless steel reinforcing bars, creating a structural insulated module capable of transferring the loads from the parapet to the concrete roof slab that supports it, while minimizing thermal conductivity between the two concrete masses. U-shaped stainless steel rebar projecting from the underside of the module is cast into the roof floor slab, while vertically-oriented stainless rebar projecting from the topside of the module is cast into the parapet, transferring moment and shear forces from the parapet to the concrete slab structure.
After the slab is cast, insulated infill units are placed between the thermal break modules to complete the continuous thermal break along the length of the parapet upstand wall.
Insulating with structural thermal breaks is also said to simplify the formwork process, reducing construction cost by up to 10 percent versus wrapping the parapet with insulation, and allows the internal surface of the parapet to be finished for terrace applications.
“This was a new product for us and for Ventana Construction, which installed them,” adds Fritz. “It’s been a bit of a learning curve to make sure that we get the installation right. To help, Schöck has been doing a formal inspection before we pour concrete.
Oceana PARC will serve as a cornerstone for development in the White Rock’s rezoned urban town center. According to Bob Fritz, “A number of other properties are in for development permits, but we’re the first in construction.”
PARC Retirement Living is the first developer/owner of senior residences in the Vancouver area to use structural thermal breaks for both balcony and parapet applications. Fritz explains, “We’re always looking to improve on the comfort, efficiency, and sustainability of our facilities. So, White Rock was the perfect setting for us to work with Schöck on incorporating the thermal breaks for parapets. If you’re going to be an owner/developer and your facility has parapets, this thermal break has significant benefit for you.”
thermal breaks for balconies
BFA Studio Architects
Read Jones Christoffersen
PARC Retirement Living