Although building codes outline specific requirements for insulation, windows, furnaces and more, some clients aim for even higher levels of efficiency and want their new or renovated buildings certified under programs like Passive House and Leadership in Energy and Environmental Design (LEED®). To meet the programs’ high environmental standards, buildings must have an energy-efficient high-performance building envelope.

Lori O’Malley, building envelope engineering specialist with PCL, has more than 20 years of experience working with project teams across North America. Collaborating early with design consultants, trades and experts through preconstruction with a specific focus on building envelope design optimization, Lori ensures that the buildings we construct meet or exceed overall performance requirements – especially with respect to moisture management, airtightness and thermal performance. 

Best outcomes are rooted in the early engagement of PCL’s in-house experts through the preconstruction design process. Integrated collaboration between the client, consultants, key trades and PCL experts is critical. Design review and development, constructability assessments, construction planning and quality management are necessary to construct an efficient and high-performing building envelope. “We try to identify performance problems at the design stage and well before we put a shovel in the ground,” said O’Malley. But an optimized design solution is only step one.

“The costs of dealing with issues after construction are often significantly more than the costs of building properly the first time,” she added. “Construction problems that could have been addressed in a few hours of consultation during construction could take weeks and thousands of additional dollars to repair afterward.”

PCL recently completed a ground-breaking project in Hamilton, Ontario: The Ken Soble Tower at 500 McNab. The City of Hamilton – seeking to set visionary new benchmarks for affordable housing – wanted to retrofit an existing and degraded 18-story housing complex to meet Passive House’s ultra-low energy EnerPhit standard. The tower is one of the first Passive House tower retrofits in North America!

To receive the EnerPhit certification, we had to meet aggressive goals for R-value (how well insulation prevents heat flow in and out of a building), air exchange rates, heating and cooling energy demands, airtightness and renewable primary energy demand. The architect predicted that, on completion, this building’s annual heating energy demand would decrease 91%, annual primary energy demand would decrease 78%, and greenhouse gas emissions would decrease 94%.

Along with a construction plan, the project team developed a detailed quality management and testing program to verify that the building envelope’s performance — especially for airtightness — was meeting the requirements set at every step in the project. This program involved measuring performance during a series of first installation reviews and at regular intervals throughout construction.

The project team also worked with trade partners to help them gain understanding of the design elements and Passive House requirements they would encounter. PCL’s superintendent, Andrew Vanderstraeten, played an essential role on the project as the air boss and worked with the trades to maintain the level of quality necessary to achieve the high standards required on the project.

“The project team’s hard work and diligence throughout the quality management and testing program resulted in the whole building’s airtightness being about one-third of the allowable amount,” O’Malley explained. “Working collaboratively as an integrated team from early preconstruction to completion, we truly exceeded expectations and successfully installed a high-performing building envelope.” 

The project team succeeded on the strength of early integrated collaboration, working with tradespeople on the project to anticipate potential risks, devise mitigation measures and rigorously manage quality at every step. “Each trade will understand their own system but not necessarily the system beside them,” O’Malley said. “Potential weak points are in the transitions between different systems and at any penetrations through the system.”

Transitions are the interface between two building envelope systems, such as glazing, roofing, masonry and metal panels. Penetrations through the building envelope occur when other systems, such as mechanical, electrical or structural components, run from the interior space to the exterior environment. Envelope transitions and penetrations represent the highest potential for performance problems and require the most planning and verification.

To optimize success, building envelope commissioning should start as soon as the project begins. Its fundamental purposes are to verify that the client’s performance requirements are included in the design,  the design is constructable and construction achieves the required level of performance.

Although third-party consultants are retained to perform building envelope commissioning on projects, PCL plays a key role in identifying risks and ways to mitigate them early in the planning process. First, we obtain a thorough understanding of the owner’s performance requirements, reviewing the design documents to identify potential constructability, continuity and material issues. Second, we develop a quality management plan that includes a well-thought-out inspection and testing program. Third, we check against performance standards early enough in the construction process so that necessary changes can be implemented while minimizing cost and schedule impacts.

O’Malley said she’s pleased to see growing recognition among both clients and builders of the role building envelopes play in energy efficiency and of the need to meet higher performance standards. “Much has changed in our industry in the last 20 years, and I think we’re heading down the right path. Current climate change realities underscore the critical importance of ensuring high performing building envelopes, and PCL is committed to modelling the way.”