By Sean Vincent O’Keefe
All Photos courtesy of Phius
Building science is more than means and materials. It’s a way of thinking and a point of pride for those who do it best. That’s the way Lisa White sees it. White is the Associate Director of Phius, a non-profit committed to decarbonizing the built environment by making high-performance passive building mainstream.
“As the certifying body for the majority of all passive house projects in North America, Phius provides a path to a zero-carbon built environment,” says White of the rubric she’s devoted her career to. Over 12 years and counting, White earned her responsibilities ground up. Starting as an intern, she matriculated through a series of roles to be named Associate Director in 2019. “Phius trains and certifies professionals, maintains and updates climate-specific building standards, and researches advancements in high-performance buildings based on passive house principles.”
“Many people who have adopted passive principles as the basis of how they design or build a home will tell you that they have a new level of pride in their work. There is more attention to detail and a different level of craftsmanship. Simply put, they build better.”
More of a method than an exact science, passive building involves applying design principles to achieve a rigorous level of energy efficiency while creating comfortable indoor environments. Though passive principles can be applied to any architectural typology, they have most commonly been the basis of single-family homes, multi-family buildings, schools and office towers.
“Passive building is a systematic way of taking a holistic approach to better building by focusing on making architecture more thermally and operationally efficient,” says White. “It just so happens these principles also make the structure healthier, more comfortable, and quieter too.”
The fundamental science behind passive building principles begins with thermal control. Objectively, a home designed to keep warm air inside during cold months and contain cold air during warm months will be more efficient and comfortable than a home that does that poorly. Achieving this requires a high-performance envelope, which means continuous insulation throughout the enclosure to reduce heating and cooling needs. To eliminate points in the enclosure where heat energy can escape known as thermal bridges, passive buildings rely on thoughtful design, conscientious installation, and integrated oversight.
Next, sealing the enclosure minimizes the infiltration of outside air and the loss of conditioned air out. The airtight envelope, however, means air from bathrooms, kitchens and humans must be intentionally exhausted and replaced with fresh air to achieve superior indoor air quality. Doing so requires balanced, continuous mechanical ventilation.
Controlling solar radiation through design and materiality is essential to preventing overheating in passive buildings. High-performance windows and doors selected for the climate the building contends with are enhanced by deliberate design orientation and shading focused on the site’s annual solar cycle. While daylighting is critical to reducing lighting loads in non-residential buildings, glazing must be properly shaded during the cooling season.
Finally, there is moisture control. Along with the airtight enclosure and continuous mechanical ventilation, detailed design specifications for vapor control maintain safe, comfortable moisture levels inside passive buildings.
“All of these things come together to create buildings that sustainably use less energy and offer greater comfort and health,” says White of the big picture.
It sounds simple enough. Not so fast. The details are in the details. Though passive principles can be applied to any building, anywhere in the world, they must be applied in a balance that is beneficial to the building in the climate where it exists.
“North America has all eight climate zones. We go from zero, the hottest, to eight, the coldest, and cover the full spectrum of dry, humid and marine ecologies,” continues White. “It’s easy to understand that a house needs more insulation in Alaska than in Florida, but there are breakpoints where the costs outweigh the returns. Phius defines how far designers should go with each principle in each area.”
By understanding the incremental value of investments in each class of considerations, the Phius certification system strives to achieve the highest possible building performance across all measures for the least cost. As a third-party industry standards and oversight organization, Phius certifies passive building success on three levels – projects, products, and professionals.
“Since Phius sets the standard, we also invest in quality assurance. We review building designs as they are developed. There is an energy model compliance checklist that stays in tune with the building as it advances to construction,” says White of a project certification process that designers must engage pre-emptively. The organization also maintains the Phius Certified Product Database, which allows designers and building professionals to assess the performance capabilities of certified building fenestration products, windows, doors, skylights and ventilator units.
Just as important as the process and the products, the people building the house must be diligent in their application of the passive principles. “We are also training and certifying building professionals to make sure that what is on paper transmits to the reality in the field. If someone is fastening four inches of rigid exterior insulation to the home, they must do it as designed. Any deviation from the specification will likely reduce the effectiveness of the insulation if the change isn’t evaluated through the energy modeling process.”
As of June 2024, Phius has certified more than 7.4m square feet of space as meeting Phius standards and established certified data on more than 800 types of windows in the product database. There are more than 1,400 active Phius Certified Professionals in North America working across a wide range of roles vital to built environment industries including designers, builders, inspectors, and administrators.
“Recently, we’ve been seeing a growing interest in the builder certification program as a trickle-down effect of more passive architecture,” says White. As in any market, in passive buildings, opportunity follows demand – what clients want, architects design, and builders deliver. “In Massachusetts, for instance, there are stretch codes that apply to multi-family housing of a certain size. Phius is one of the options developers can choose. So first, there was a rush of designers and engineers getting certified, and now builders and subcontractors are going through our training programs.”
Within the Phius training program, there are four professional certifications available (Phius Certified Builder (CPHB), Phius Certified Consultant (CPHC), Phius Certified Rater, and Phius Certified Verifier.
Phius Professional Certifications
Phius Certified Consultant CPHC– Recommended for all project types. A CPHC works with the project team throughout the design process to ensure the project will meet all certification requirements. This includes completing the WUFI passive energy modeling for performance path certification.
Phius Certified Builder: CPHB – Recommended for all project types. The CPHB is responsible for understanding the construction documents and executing them on-site. The CPHB sources the intended materials and oversees their installation per specifications. In addition to documenting the construction process, the CPHB is responsible for tracking adaptations or alterations from construction documents or specifications. Such considerations must be communicated and coordinated with the CPHC and the Rater or Verifier.
Phius Certified Rater: Required for single-family detached and may be used for single-family attached and townhouses. Responsible for site visits, testing, and verification during construction, the Rater is an integral part of the project team – best integrated early. The Rater must issue a Letter of Intent before the project can receive a Design Certification.
Phius Certified Verifier – Required for non-residential and multifamily projects and may be used for single-family attached and townhomes. The Verifier is responsible for site visits, testing, and verification during construction. When required, hire the Verifier early. Verifiers must issue a Letter of Intent before the project is eligible for a Design Certification.
“The biggest benefit of the Certified Builder program is that a certified builder is going to do a better job, faster, with less incremental cost than a non-certified builder,” says White. “Non-certified builders working on passive house projects can build them correctly, but they tend to have a lot of overhead because they don’t know how to account for some of the materials and design strategies. Certified builders produce better buildings right from the estimate with greater accuracy and in less time once they understand the process and logic.”
As an example of what to expect, within the builder certification program, an individual registrant would pay $2,100 to engage in a three-month certification process. The program begins with 8 to 10 hours of self-guided instruction on the physical science of passive house principles as foundational knowledge. Next, they take 24 hours of instructor-led training, typically delivered in 8, 3-hour sessions, delivered by two or three certified instructors. When the instruction is complete, the examination period follows. Though open-book with a 30-day time allowance, the CPHB exam is rigorous. Once submitted, grading takes approximately four weeks. The test returns with a grade, feedback, and credentials for those who pass.
“We also partner with firms or organizations who want in-person options,” says White of the program’s adaptability to user needs. “In that case, it becomes 3, 8-hour days of on-site training, followed by the same 30-day testing period for participants.”
As an industry-invested partner of some 20 years, Phius still strives to increase impact and the positive uptake of passive principles in mainstream residential buildings.
“We recently launched a passive building foundations training program, which could be useful for an estimator or administrative professional responsible for tracking this,” continues White. “There is also a trade training program with a specialty designation intended for people installing the equipment or building these houses.”
As for a takeaway, beyond the improved building performance, operational efficiency, and the clean, quiet comfort of a passive house, White points to pride.
“Many people who have adopted passive principles as the basis of how they design or build a home will tell you that they have a new level of pride in their work,” finishes White. “There is more attention to detail and a different level of craftsmanship. Simply put, they build better.”
