As the passive building movement continues to gain momentum globally, Blake Jackson breaks down the PHIUS CPHC certification—and what it can mean to communities
Before we begin, it’s important to note that there are two separate entities promoting the passive building movement: the Passive House Institute (PHI), based in Germany, and the Passive House Institute US (PHIUS), which promotes a version of passive building that has been adapted for the North American climate. In this blog post, we will be exploring PHIUS.
Passive House began in Germany in the 1980s as a concept for ultra-energy-efficient buildings. Gaining momentum in the US, it has since been adapted by Passive House Institute US (PHIUS) for all American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) climate zones to reduce site energy use by 65-80%, while also promoting water conservation and improved indoor air quality (IAQ).
PHIUS offers something for everyone. End users benefit from lower bills, noise reduction, and increased thermal comfort. Designers benefit from a streamlined design process that uses prescriptive performance to improve thermal envelopes, while promoting mechanical systems that are simpler to operate and maintain. Municipalities champion it as a tool for leveraging development to curb greenhouse gas emissions while providing social equity through housing affordability and noise reduction. Municipalities also promote the increased resiliency through durability and passive survivability, which allows buildings to continue normal operations in the event of a disruption in service.
Passive House is being codified in Canadian cities like Vancouver, Toronto, and Edmonton, while US states, including Pennsylvania, New York, and Massachusetts, are incentivizing single- and multifamily pilot projects to promote and proliferate the concept.
So, what sets PHIUS’ Certified Passive House Consultant (CPHC) designation apart from the rest? And what role does it play in enhancing our projects and communities?
Rendering of the Northland Needham Street Master Plan in Newton, Massachusetts. Passive House certification is being sought for many residential buildings.
_q_tweetable:PHIUS offers something for everyone: end users have lower energy bills, designers have a streamlined process, and municipalities can curb emissions._q_
An applied, real-world approach
This credential matters because it prepares candidates with proven concepts and real-world tools to rapidly implement Passive House design at any scale and building type, which will be crucial in meeting stringent municipal goals in key growth areas across North America. Passive House is a formula for prescriptive performance and outcomes that will help clients, organizations, and communities combat, mitigate, and potentially reverse the effects of climate change.
Unlike many other credentials, whereby testing is a measure of one’s ability to commit theory to memory, CPHC is about applied principles. This is evidenced in the onsite charettes and open-book examination required during the certification process, along with an architectural/mechanical design exercise scrutinized by PHIUS building scientists. Having this credential means one understands sustainable building practices and can implement Passive House, rather than merely studying a rating system yet never applying it to an actual project.
Passive House in the community
Here at Stantec, four of our design professionals recently earned CPHC certification, and the value that it is bringing to our clients is already manifesting. We are working on several large-scale masterplans that are committing portions of their residential square footage to meeting Passive House certification.
Developments such as the Union Square (USQ) Revitalization in Somerville, Massachusetts, and the Northland Needham Street Master Plan in Newton, Massachusetts, are projects starting with Passive House in mind. Projects like this support developer goals and rising municipal priorities for more sustainable development.
In both cases, Stantec has strategically placed CPHC-credentialled staff in key positions on the team to guide the design process and help our clients understand what they’re required to commit to while navigating the often-tedious municipal permitting and approvals processes. Having this expertise integrated from the beginning is a wonderful advantage that sets the tone for future success that can be predicted, priced, and designed early in a project.
Overview of the credentialing process from start to finish.
Candidates begin by registering with PHIUS and meeting one of the following acceptance pathways: licensure, recognized professional, education qualification, field experience qualification, or by being a PHI-certified consultant or designer.
Phase I—Self-guided study: Paid registration grants access to approximately 45 hours of online webinars in varying lengths, covering everything from PHIUS basics to advanced building science—each with a quiz at the end. Having the elements divided into separate lessons allows candidates to self-pace their study around work and personal commitments. Phase I modules, a prerequisite for Phase II, remain open one year from registration.
Phase II—Intensive: The intensive happens over the course of the week. The first half includes an introduction to Passive House, a review of architectural systems relative to the standard, an interactive group design charette on a sample test problem, building science calculations, and WUFI Passive tutorials. The second half of the week includes a THERM tutorial, a mechanical review of Passive House principals, another interactive group design charette, and an overall session Q&A.
(Left) WUFI assembly for a roofing joist and (right) an isothermal analysis of a PHIUS-compliant footing detail.
Tools: Projects start in WUFI, importing simplified models from SketchUp. Models capture only the interior calculated floor area via exterior envelope elements (roofs, slabs, walls, and glazing/doors). Most of the work includes constructing project-specific assemblies and assigning them performance values, which becomes streamlined as internal libraries build up over time.
Once a model demonstrates it is theoretically compliant, a PHIUS review is triggered, encouraged as early in the design phase as possible. This is unlike typical energy modeling, which comes too late to inform design. This approach is innovative and practical for projects of all sizes, utilizing modeling to inform performance throughout design, not as a relic of the design decisions made at the end.
After the review, PHIUS specifies assemblies to be modeled in THERM, which would be areas needing close attention due to their potential to introduce thermal bridging. Two-dimensional imported CAD drawings of assemblies are uploaded and imbued with performance values, based on their materiality. When completed, isothermal simulations can easily identify thermal bridging and dew point locations visually, which is helpful for design teams during detailing to quickly be able to reconfigure assemblies to comply.
Example of a construction detail as part of the take-home project—not a perfect solution but a passing solution!
Phase II—Exam: The three-hour, in-class exam is administered the last day of class. To earn the CPHC designation, candidates must pass the in-class exam and a four-week take-home individual design project with a cumulative average of +70%. Albeit open book, the exam is very difficult, referencing specifics from both phases, including 10 calculations problems. The take-home project makes up the remainder. The exam automatically times-out after three hours, and students get their results immediately.
Phase II—Take-home: A link to the take-home project, a design for a PHIUS+ 2018 compliant single-family dwelling, is given after the exam and due within four weeks. This project is climate/program-specific, and the deliverable is limited to a 10-page file with plans, elevations, sections, specifications, and details demonstrating PHIUS+ 2018 compliance.
Hard work—but it’s rewarding
The credential is strenuous to earn! The process, if timed appropriately, can be accomplished in approximately 150 hours: 50 hours each for Phase I, the onsite intensive, and the take-home project. Interested candidates may submit registration requests at any time; however, they should wait to pay for and complete Phase I until confirmed for an onsite Phase II seat to avoid spreading the process out over several months. Additionally, taking good notes during Phase I saves time during Phase II, as they can be used during the open-book examination.
CPHC is a greater investment of money and time than other systems’ credentialing. By comparison, the LEED/WELL AP exams cost $450/$600 (non-members), while PHIUS is $2,100 (non-members), not including time and travel expenses. Savings can be incurred through joining the Passive House Alliance US (PHAUS).
Lastly, be prepared to work! Students must provide their own laptops for the whole intensive and come with the provided software already downloaded. Additionally, candidates should be prepared for nightly homework, specifically for the calculations. I had not anticipated this; however, our group formed informal study groups that stayed after-hours, which was helpful and contributed toward it being a memorable experience.
Will this be your year for CPHC certification?
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