Canadian Architect

Feature

Bringing Passive House into the Cold

October 18, 2018
by Dr. Andrea Frisque (P.Eng) and Marc Trudeau (P.Eng, Architect AIBC)

British Columbia (UNBC) has a public mandate to be a leader in high-performing buildings and innovative wood projects. Working with UNBC, our design team at Stantec conceived the new Wood Innovation Research Laboratory (WIRL) as a research, testing and development facility for these products. The building allows faculty and students in the Master of Engineering program to conduct unique experiments, test theories and explore creative uses for wood in sustainable design.

UNBC, Passive House, Wood Innovation Research Laboratory

The Wood Innovation Research Laboratory in Prince George at UNBC is the first North American university building to meet the Passive House standard.

In keeping with a sustainability mandate, we designed the WIRL as North America’s first certified Passive House higher education building. Passive House principles were followed in all phases of the project—through design, engineering and construction. Building to Passive House standards is challenging in any climate, but exception­ally so with the cold weather in Prince George.

With its rigorous criteria, Passive House sets a stringent standard for building energy efficiency and occupant comfort. It was initiated to achieve design quality assurance in Europe in the 1990s, with certifica­tion pioneered through the Passive House Institute (PHI) in Darm­stadt, Germany. The standard now has international attention, with Passive House criteria impacting Canadian building codes. For example, the City of Vancouver accepts Passive House certification as one way to demonstrate compliance with its new rezoning policy.The Wood Innovation Research Laboratory in Prince George is the first North American university building to meet the Passive House standard.

Passive House and European energy codes (known there as direc­tives) have been based on absolute energy metrics for decades. The same type of metrics—which relate to heating demand, energy use and airtightness—are now used in British Columbia’s step code. This is a change from traditional North American codes, such as ASHRAE 90.1 or NECB, which are based on percent savings.

The WIRL project started with research by the faculty well in advance of the RFQ, particularly by Guido Wimmers, chair of the Master of Engineering program at UNBC and an expert on Passive House construction. The project was officially launched when Wim­mers, together with Shelley Rennick, director of facilities management at UNBC, received $1.88 million in federal funding from the Post-Secondary Institutions Strategic Investment Fund. The project’s remaining $3.44 million construction cost was funded by the provincial government of British Columbia’s Ministry of Advanced Education, Skills, and Training in partnership with the university.

As Passive House projects are still rather new in Canada, keeping track of project costs was a priority throughout design to control expenses and make effective economic decisions. The WIRL was delivered as a design-build, with Passive House certification as a contractual requirement.

The Wood Innovation Research Laboratory in Prince George is the first North American university building to meet the Passive House standard.

n the cold climate of Prince George, the thermal performance of all assemblies needed to be significantly improved beyond typical practice. This includes, for example, triple-glazed windows with overall U-0.76 W/m2K (U-0.13 BTU/h ft2F). It also includes roof, walls and floor with effective clear field thermal performance of U-value 0.057, U-0.079, and 0.166 U-0.76 W/m2K (R-value 100, 70, 34 h ft2F/ BTU) respectively.

Achieving Passive House energy and building envelope performance levels required meticulous planning in wall assembly construction, sealing of membranes, and consideration for air leakage at all inter­faces—especially around openings such as the garage door. Our team sourced building components and systems both locally and from abroad. The overhead door was provided by Hörmann and delivered from Germany. Doors and windows from European manufacturers were selected for performance that meets Passive House requirements.

The 900-square-metre single-storey structure comprises a glulam post-and-beam superstructure over an insulated raft foundation. Initially, our team considered using mass-timber wall and roof assemblies with outboard insulation, but found that this approach was not cost-effective. A more feasible solution was achieved with a wall assembly that pairs standard residential roof trusses with sprayed mineral-wool insulation. The wall and roof structures were made using conventional building materials and fabricated in Prince George by Winton Global, a local residential truss manufacturer, although the wall-truss design was customized to meet Passive House requirements.UNBC, passive house

The wall trusses are 10 metres tall by 2.9 metres wide, designed based on 1.47-metre-wide sheathing modules. Prior to tendering the wall panels, the design team created drawings of all modular panel configura­tions, both to communicate the design intent and to bring the price down from the trades by establishing a level of certainty and clarity.

The non-local materials in the envelope are the Intello air/vapour system, developed by Pro Clima in Germany, and the blown mineral wool insulation from Indiana. The whole wall structure was fabricated in a factory, transported to site, and craned into place, after which the insulation was installed in situ.

An integrated strong wall and strong floor allow for simulated destructive structural testing, in which materials are stress-tested until they fail. The workshop’s high-bay fabrication area also includes machining equipment, wood cutting tools, and wood drying capability. The considerable ceiling heights allow large sections of building materials to be assembled, moved by overhead crane, carried to the testing area, and loaded onto delivery vehicles.

Lofty ceilings and a garage-door entry present a particular challenge in a Passive House design, as there are significantly more surfaces that can lose heat and allow air to infiltrate. This challenge is somewhat mitigated by the lower air temperature needed in the workshop space. We took exceptional care to consider how specific project components worked together in order to achieve a feasible integrated Passive House design.

The south side of the building is a source of heat, views, and natural light for the office and seminar spaces. The south façade is also where the air intake for the building is located, strategically positioned to draw air from a future adjacent park.

The completed construction has set a high standard for airtightness, securing the best North American result of any building under the Passive House standard. Passive House sets limits on airtightness with a maximum allowable infiltration of 0.6 air changes per hour at a pressure of 50 Pa. The WIRL building achieved a result of 0.07 air changes per hour, surpassing the already stringent Passive House requirement by nearly a factor of ten. Typical Canadian building stock achieves in the range of 3 to 10 air changes per hour.

Students at UNBC now have a beautiful, sustainable and modern facility for conducting research on new uses for wood—which will ultimate­ly aid in developing new jobs and markets in the forestry industry and helping British Columbia to secure a sustainable future.


Dr. Andrea Frisque is a Senior Building Performance Engineer and Associate based in Stantec’s Vancouver office and Adjunct Professor at the School of Architecture and Landscape Architecture, University of British Columbia. Marc Trudeau is Building Performance Engineer and team lead for the Sustainable Buildings Studio in Stantec’s Vancouver office.

Photos by Michael Elkan.



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