THE BELMONT | BUILDING ENVELOPE RENEWAL - Vancouver, BC
JURY COMMENTS - The project represents an important collaboration between a number of stakeholders including the federal government, provincial government, utility companies and engineering consultants to address one of the more pressing problems in the built environment. The jury was impressed with how the design team turned the envelope renewal on this 1980s building into an opportunity. They took a systematic approach to recladding that has increased the value of the asset both through improved aesthetics and enhanced energy performance. The cladding eliminates the thermal bridging inherent in steel stud construction and offers a solution that could be transferred to literally thousands of other similar projects.
The National Institute of Building Sciences estimates that over 70% of the buildings that will be present in 2030 already exist. The energy efficient renewal of existing buildings is therefore paramount to reducing our environmental footprint.
Originally constructed in 1986, The Belmont is a 13-storey residential building on the west side of Vancouver. After weighing various options on how best to maintain and reinvest in its property, the Strata Corporation decided to proceed with a building enclosure renewal project in 2012.
A cost payback analysis was performed to assess the financial feasibility of each energy efficiency measure based on its incremental cost above the baseline budget and the predicted energy savings.
Implementation followed a whole building systems approach, that first considered passive strategies to reduce the heating load, with future plans to improve the mechanical systems. Heating energy was reduced through a highly insulated building enclosure, energy-efficient windows, and airtightness improvements.
The existing exterior walls were exposed cladding with 50mm of foam insulation at the inside, with an overall effective R-value of R-4. For the renewals project, the walls were over-clad with 89mm of mineral wool insulation behind stucco and metal panel cladding. The cladding and insulation were held in place using fibreglass ‘Cascadia Clips’, which significantly reduce thermal bridging compared to a more traditional metal girt cladding system. This assembly resulted in an overall effective R-value of R-16 for the exterior walls.
With a window-to-wall ratio of 50%, the windows accounted for a significant portion of heat loss. The existing windows consisted of double glazing with air fill and no low-e coatings in non-thermally broken aluminum frames. These were replaced with triple-glazed windows with fibreglass frames, improving the window U-value from about USI-3.1 [U-0.55] to USI-0.97 [U-0.17].
Airtightness improvements were made to the enclosure through installation of a liquid-applied air and water barrier over cracks in the concrete, best practice detailing at interfaces and penetrations, and new airtight windows. The whole building airtightness was tested before and after the retrofit. The initial pre-retrofit airtightness was 0.71 cfm/sf at 75 Pa. Following the retrofit, the airtightness dropped to 0.32 cfm/sf at 75 Pa.
Energy savings as a result of the enclosure renewals project were estimated through whole building energy modelling, and are predicted to be 20% in overall building energy, and 90% for in-suite space heating energy. This retrofit should nearly eliminate the need for electric baseboard heating and cut total building suite heating costs from $18,000 to just $2,000 per annum.
- Owner Strata Plan VR 1647
Consultant RDH Building Engineering Ltd.
Photos RDH Building Engineering Ltd. [taken by various RDH staff], and Paul Grdina Photography
- Metal panels fastened with fibreglass Cascadia Clips 3.5”
- Roxul CavityRock DD insulation used within the rainscreen wall cladding assembly
- Stucco system by Imasco Minerals Inc.
- Fibreglass-framed 300 series tripled-glazed windows, low-e coating and argon filled by Cascadia Windows and Doors Ltd.
- Skylights at penthouse levels only