Recap and Reflection from the Phius Non-Res Summit 2025

Since 2021, Phius has hosted an online summit each spring – a succinct, two-day webinar series to present ideas from thought leaders in the passive building community focused on specific topics. 

The inaugural summit in 2021 focused on mechanical systems, 2022 was targeted toward developers, 2023 for policymakers, and 2024 discussed retrofits and the new REVIVE 2024 standard. This year, the topic was a direct response to adoption of Phius standards as a code compliance path, and the increase in non-residential projects getting submitted to Phius for review and certification.

Phius has worked diligently to ensure that the standards, guidelines and tools are designed to allow for buildings of all types to certify. The terms “passive building” and “passive house” get used interchangeably frequently in our circles, but we at Phius strongly advocate fo the use of the term passive building to ensure inclusivity of all building types. 

Each day of this year’s summit had a distinct topic: the first being two case studies presented by Tom Boeman, Owner of Boeman Design; Julie Kriegh, Founder & Principal of Kriegh Architecture Studios; and Julie Blazek, Partner at HKP Architects. The second day featured Phius staff members Haley Harlow, James Ortega, and yours truly. We covered some of the critical necessities for getting non-residential projects through the certification and modeling process.

Day 1: Phius Non-Res in Action

On Day 1, Tom highlighted the work on his first passive building project, the Prairie Trails Early Learning Center in Mount Prospect, Illinois. 

This boxy, mid century school building underwent a major renovation to achieve Phius+ 2018. The school was featured on the bus tour during the PhiusCon 2022 in Chicago, and represents a leading project in both the non-residential and retrofit realms. 

The school was upgraded with new insulation all around, a new cladding, and triple-glazed windows. The mechanical space conditioning is provided by a VRF system, while a few different zoned dedicated outdoor air systems (DOAS) cover the mechanical ventilation. Tom pointed out that there were quite a few DOAS zones implemented on this project, and he would have reconsidered zoning. He was also quick to point out that the coils in the DOAS system do more space conditioning than one might realize when looking at the sizing, as the overall load on the building has been significantly reduced thanks to the passive envelope. This was the first passive building I had ever been in on the tour in 2022, and I distinctly remember the closing of the door eliminating the rumble of the diesel coach bus on which we arrived.

The second project presented was by Julie and Julie, talking about the recently completed Phius+ 2018 Certified Mount Vernon Library Commons in Mount Vernon, Washington. The project features a unique design in an urban context, with the parking located on the roof of the building, allowing patrons to walk in off the street without fear of having to cross a parking lot to get to the building. The community had significant input into the project, saying they wanted a building that was sustainable and responsible to the climate. 

The architect and engineering team responded by leveraging the Phius standard to achieve a building that is thermally comfortable and resilient to a changing climate, in addition to reduced energy demand, which saves the city’s residents money. The library this project replaced had an EUI of 66 kBtu/ sf yr and the new library has an EUI of 12. Julie and Julie also stressed the importance of a diverse team and integrated management of the disciplines to pull off a successful high-performance building.

Day 2: Certifying a Non-Res Project

The second day featured the expertise of Phius staff to explain some of the subtle nuances of certifying a non-residential project with Phius. 

The most important things to note here are as follows: 

• Non-residential projects require additional side calculations as the internal gains and building system controls are more flexible, and more complicated.
• The internal gains section is the most radically different from the residential modeling, where all of the usage patterns for appliances and equipment are default, and the non-residential are non-default and require narratives and calculations to confirm.
• The general Phius targets are good for buildings that are similar in load and ventilation demand to a school or to an office building, but increased ventilation and/or internal gains, such as a hospital, require custom target optimization under the current Phius standards.

In summary, the Phius Non-Res Summit 2025 represented a great opportunity to learn more about what is being done in the non-residential space currently and some great case studies. As of the date of this blog’s publication, Phius Certified 534 projects, 43 of which are non-residential, and this portion is likely to grow much more in the coming years.