Capstone Development Partners is teaming with Steven Winter Associates (SWA) on Portland Commons, a new student housing facility being developed in partnership with the University of Southern Maine. Upon completion, Portland Commons, will be the largest Passive House residence hall in the Northeast. We sat down with Thomas Moore at SWA to talk more about Passive House and why this relatively new sustainability model makes sense for college campuses as a long-term facility operations savings and efficiency model.
The International Passive House (PH) standard is the most stringent energy efficiency certification currently available. PH buildings reduce energy use and decrease carbon emissions to help projects align with sustainability and climate goals. While the PH standard is rigorous it also offers extreme flexibility to the design team since certification is performance-based, rather than prescriptive. This flexibility means that PH buildings can be any type and include any building program. Further, the PH standard offers a simple and straightforward design approach.
All PH buildings implement the following 5 simple design principles to achieve an extraordinary level of energy efficiency: (1) air-tight envelope, (2) continuous insulation, (3) high performance windows and doors, (4) thermal bridge free construction, and (5) balanced ventilation with heat recovery. These design features are fully realized with stringent quality control checks during construction.
While the Passive House concept is much less common in North America than in other regions such as Europe, the concept is growing in the United States with more US colleges and universities building to PH standards. Currently, Capstone is partnering with SWA, a Passive House consultant and specialist, on the design of Portland Commons, a new 580-bed undergraduate student housing community on the University of Southern Maine’s Portland campus. SWA has also worked with the University of Toronto, Cornell and is currently working with New York University to either build new or adapt existing student housing facilities to Passive House standards.
So how does Passive House differ from other sustainability programs such as the USGBC’s LEED program?
The difference is that Passive House is strictly a performance-based standard for buildings that focuses on energy, comfort, and durability. This performance-based approach requires that a detailed energy model is developed during design, and that performance is verified during construction. This is achieved through a design, build, and verification process. At the end of construction, a final blower door test is completed to confirm just how air tight the building is, and groups such as SWA verify that the ventilation system is operating as intended with balanced supply and exhaust flows. Some additional benefits of Passive House include affordability, healthy filtered indoor air, thermal comfort, a quiet interior, resiliency to extreme weather, building envelope durability, additional construction quality assurance and control for the owner, carbon emission reductions and net zero energy ready compatibility.
What is the recipe for a successful Passive House Project?
1. Establish the goal of Passive House certification at project onset. Assemble your qualified design and construction team early in the process with the goal that the project be designed to Passive House standards. While not prohibited, it would be difficult (and likely expensive due to re-design) to decide at the 50% Construction Documents milestone that your team wants to pursue at Passive House for the project. Further, because the integrated design process is absolutely critical for a successful PH project, selecting a team that is experienced and capable of designing and constructing to PH standards is important. At Portland Commons, the SWA team was involved from the outset and worked closely with the mechanical engineer and architect at all times, as opposed to working in silos and passing drawing documents back and forth.
2. Trade Screening and General Contractor Training. If you choose to design your building to Passive House standards you should look to select a design-builder / general contractor that either has, or is willing to obtain, certification as a Passive House Institute US, Inc (PHIUS) Certified Passive House Builder (CPHB). It is one thing to design to PH standards, but quite another to have quality execution to meet the PH tests at the end of construction. So, be sure to have a general contractor that has trade screening or that is willing to take on trade screening so that critical subcontractors are knowledgeable of and qualified to build to PH standards.
Designing a Student Housing Community to Passive House Standards
Integrating a Certified Passive House Designer at the beginning of the design process can minimize the time and associated costs of achieving a PH design. As with all developments, an important part of the process is evaluating, vetting and selecting design features, building systems, finishes and components that meet the specific goals and objectives of the project as established by the owner. This is especially true when selecting features that are appropriate for PH. By way of example, on the Portland Commons project Capstone, SWA and the design-build team selected specific envelope materials (windows, doors and walls systems), HVAC systems and equipment, highly efficient domestic hot water heating, lighting fixtures and appliances to meet the PH standards for the Project. With SWA on our team from the outset, we were collectively able to evaluate the ‘means and methods’ of achieving each of the PH program requirements while overcoming some of the challenges of constructing through two Maine winters. For instance, by utilizing SWA’s PH energy modeling capabilities we were able to utilize a pre-fabricated exterior wall assembly that will minimize labor costs on-site, meet PH envelope airtightness requirements, and ultimately reduce Project costs. We also worked with SWA to identify and certify an alternative PH window that meets all of the requisite criteria without the premium associated with the other PH certified window. Similarly, the team worked directly with the mechanical engineer, SWA, and an HVAC vendor to select a highly efficient, more cost-effective custom Energy Recovery Ventilator (ERV) that meets the PH standard. Open communication and a highly integrated design process were key to achieving all of our PH goals.
Is Passive House the next wave of sustainability standards in the US for colleges and universities?
Given the benefits of PH, it is logical that more and more colleges and universities in the US will consider and/or adopt Passive House standards for buildings on their campuses. Several progressive universities such as NYU, Cornell, University of Toronto, University of Vancouver, the University of Southern Maine and several other institutions along the east and west coasts are already embracing the standard. A Passive House building decreases operation costs and carbon emissions which helps institutions achieve aggressive climate goals, while also offering an improved indoor environmental quality which directly improves the student resident/occupant experience. A key to realizing the full benefits of Passive House is including PH goals on projects that will be held for long-term. One of the primary benefits of Passive House is the long-term operational savings that are generated, making Passive House a perfect candidate for student housing and other higher educational buildings that typically are built with a life expectancy of many decades, if not a century or more.
Authors: Walker May, CDP Executive Vice President and Thomas Moore, Steven Winter Associates Building Systems Analyst