Building envelope systems
Project location: CanmetENERGY Ottawa, Ottawa, ON
Timeline: 4 years (2019 to 2023)
Program: Built Environment
Our team is developing, testing, and validating innovative building envelope technologies to improve the energy efficiency of the envelope assembly by at least 50% (compared to current building codes) and to significantly reduce greenhouse gas (GHG) emissions (compared to current construction practices). We aim to do this for both retrofits and new construction, using factory-fabrication processes, innovative insulation materials, and cost-saving construction methods.
Our research focuses on three priority areas:
- Prefabricated exterior envelope technologies and assemblies for the retrofit of existing housing
- Prefabricated, highly insulated thin walls for new housing
- Design and construct the CanmetENERGY Ottawa Envelope Research Building, and establish (in collaboration with Carleton University) the Centre for Advanced Building Envelope Research (CABER), located at CanmetENERGY Ottawa
A description of each priority area is provided below along with a brief description of sub-projects that support each research priority.
Prefabricated Exterior Energy Retrofits (PEER)
Canada’s 14.5 million dwellings account for more than one sixth of national energy use, and close to 14% of Canada’s energy-related GHG emissions. More than two-thirds of these dwellings were built before the existence of residential energy efficiency standards. Nearly one million homes have benefitted from retrofit program incentives to date, but exterior wall insulation improvements are historically uncommon. This, despite the fact that exterior walls can account for 25-35% of heat lost in the typical existing home. Research has shown that there are many barriers to exterior wall retrofits, including unpredictable costs, occupant and neighbour disruption, long completion times, and risks related to moisture.
The PEER project addresses the need for energy-efficient exterior wall retrofits through the adoption of a prefabricated solution for existing dwellings. This research project is undertaken in several phases as outlined below.
Phase 1: Proof of concept
In 2017, our team at CanmetENERGY Ottawa (CE-O) initiated a proof-of-concept, pilot-scale field installation process. We focused on developing technologies and processes to apply two types of prefabricated wall panels and component prototypes in order to retrofit an existing building from the outside. This approach promises to dramatically improve energy efficiency and enhance aesthetics, while addressing the above-noted barriers including project costs and complexity of conventional retrofits.
Phase 2: Monitoring exterior wall assemblies
To understand how moisture transfer occurs through the retrofitted wall assemblies, our team at CanmetENERGY developed and implemented a monitoring protocol. This involved installing temperature, relative humidity, heat flux, and moisture content sensors in the wall assemblies used in Phase 1, thereby allowing us to measure the in-situ hygrothermal response of the assemblies to actual (Ottawa) climate loads over several years. Ensuring conditions are not favourable for mould and fungal growth are the main durability evaluation criteria.
Phase 3: Exterior retrofit of an affordable housing project
Building on the lessons learned from Phase 1 of the project, our team, in collaboration with Ottawa Community Housing, has now embarked on a deep energy retrofit (to net-zero energy performance) of a four unit, two-storey housing project built in the early 1960’s. The retrofit uses a prefabricated panel methodology and approach to install above-grade exterior walls and roof assemblies. Furthermore, our team is investigating the total cost of building ownership, building capture technologies and processes, building design and condition assessment, and post-occupancy monitoring, verification and assessment protocols.
High-R, thin wall assemblies
High performance housing standards in Canada, including ENERGY STAR, Net-Zero Energy and Passive House, require large amounts of insulation compared to homes designed and built to conventional code requirements. In order to achieve the necessary thermal resistances [typically RSI 5.0 to 8.8 (R 28 to R 50)] to meet these standards, homebuilders have traditionally used thicker wall assemblies – often twice as deep as conventional walls.
The “High-R, Thin Wall” project explores the integration of insulation materials having low thermal conductivity for use in wood-framed wall assemblies. In partnership with industry and academia, for example, Owens Corning and Carleton University, respectively, our team develops and evaluates innovative, proof-of-concept wall assemblies including an insulated module comprised of an extruded polystyrene (XPS) and vacuum insulation panel (IP) system, intended to insulate and air-seal a wood-framed wall from the exterior. With this innovative wall panel assembly installed in the field test hut, located in the Bells Corners Campus, the team assesses the hygrothermal response of the panel to actual climate loads and then compares its performance to conventional code-compliant wall assemblies.
CanmetENERGY Ottawa’s Envelope Research Building
CanmetENERGY Ottawa is constructing a new building on our Bells Corners Complex, which will house our building envelope research and development (R&D) program. The new building will also be used by Carleton University’s Centre for Advanced Building Envelope Research (CABER) program. Our R&D program, combined with CABER’s, support fundamental and applied research associated with developing high-performance building envelope façades for the residential and commercial sectors.
The equipment and facilities included in the CanmetENERGY Ottawa’s Envelope Research Building will enable a broad and comprehensive research program that includes the study of building enclosure assemblies, their component materials, and their impact on occupant comfort.
- Hygrothermal properties of building materials will be evaluated in the Material Characterization Laboratory.
- The Occupant Comfort Laboratory will facilitate assessment of visual and thermal comfort achieved through the application of various building façade systems and design strategies. Full-scale residential and commercial wall assemblies will be evaluated through laboratory testing; using combinations of the Guarded Hot Box and Pressurized Spray Rack, intended to simulate representative climate conditions from across Canada including wind, solar heating, temperature and humidity. In addition, the building’s envelope is designed in such a way to permit the insertion of test walls within the façade to allow for the evaluation and assessment of the long-term climate exposure impacts.
- Magazines – used to hold the full-size test wall specimens – will allow for transporting the specimens from the test apparatus by overhead crane, and for specimen storage.
The building will enhance CanmetENERGY Ottawa’s ability to collaborate, by providing space for our team to work with Carleton researchers and CABER’s partners – including Algonquin College, Concordia University, and the National Research Council.
Contact CanmetENERGY in Ottawa
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