Mechanical Summit Re-cap: A Good Time Was Had by All

Al Mitchell

Phius technical staff member Al Mitchell is our guest blogger, providing a thorough re-cap ofthe Phius Mechanical Summit. Remember that the entire proceedings were recorded, and you can still register to view all four or any of the days a la carte. You can earn up to 16.5 CPHC CEUs.

In the week leading up to Earth Day, Phius hosted the  Mechanical Summit online, a virtual gathering to advance the conversation around mechanical systems in passive buildings. Some came for direct solutions to their problems, some came for involved discussion between designers and manufacturers, some came for CEUs, but everyone had a rousing good time.

The summit was organized into four days, each with a defining theme. Pre-recorded presentations from expert panelists were available on-demand and led up to a two-hour live webinar; each featured a lead panelist presentation and short distillations of the pre-recorded presentations, after which the panelists fielded questions from the live audience.

Attendees asked their questions via the Zoom webinar format, but the chat remained open for the audience to debate and respond to different ideas.

The first of four days detailed building mechanical design principles and best practices. Lead panelists Dan Whitmore and Sloan Ritchie discussed their past experiences and used previous projects as case studies to demonstrate how they developed mechanical solutions for their Pacific Northwest climate. Other presentations included topics such as properly-sized domestic hot water distribution systems, ventilation integrated space conditioning, proper duct sizing, and rater-focused commissioning and testing of systems for passive house certification.

On the second day, presentations focused on solutions for closing the gap and tools and strategies to respond to the design principles. Lead panelist Tim McDonald detailed mechanical designs from multifamily projects located in the Philadelphia, Pennsylvania area. He explained his incremental development of mixing an ERV and ducted heat pump system by dumping the fresh air supply from the ERV into the return of the heat pump, and eventually trying a ventilation and space conditioning integrated unit. Other presentations explained proper space conditioning load sizing for single family homes, building monitoring and comparing results to predicted outputs, design of space conditioning integrated ventilation units, and mechanical systems controls.

Day three dealt with products and systems designs. Lead panelist Chris Benedict presented on a retrofit project in Brooklyn, New York, where the mechanical systems and building enclosure were rebuilt with minimal tenant disturbance. This raised questions on system choices and detailing the complicated world of building retrofits. Other presentations included manufacturers explaining improvements to their products and how they are responding to the needs of passive building designers, and some design methodologies and installations that are aimed at efficient, low carbon mechanical systems.

The closing dayffeatured Doug Farr, determined architect and new urbanist from Chicago. He celebrated Earth Day and discussed how to build a ground-up movement to build more efficient and sustainable communities, a more optimistic and engaging approach to the problem compared to many top-down approaches. To carry off at the neighborhood level, the additional presentations detailed building electrification, smart DC low voltage power systems, and passive buildings’ interaction with the grid. PHIUS Executive Director Kat Klingenberg made another nod to Earth Day and unveiled the new Phius branding and re-alignment to the institute’s mission.

There were a few themes that seemed to interweave through the days. One is the ever-popular question of kitchen range hoods and managing make-up air for direct exhaust devices. Without fail, it was discussed on all three mechanically focused days of the summit. While the panelists and attendees presented multiple solutions, no “silver bullet” solution emerged. This represents the reality of many passive buildings, that a one-size-fits-all solution is not available, and each project requires a thoughtful and inquisitive design professional to determine the correct path.

Many panelists mentioned that they felt that the building enclosure is the easy step for them, and the mechanical systems require more thought. A lot of these issues have been known from the beginning: the need for balanced ventilation, tight enclosures, and the massive reduction in sensible and increased need for dehumidification. Some designers called on manufacturers to address the need for microload equipment, and the manufacturers’ representatives showed some products in the works, and made the case for increased demand to bring the types of mechanical products to the North American Market. Seeing the large uptick in Phius Certified buildings, there is good reason to be optimistic.

While mechanical systems are frequently seen as the weak link in passive building design, the Phius 2021 Mechanical Summit left many feeling sanguine. Phius will continue to work and keep the conversation going on mechanical systems moving forward. Help Phius continue the conversation and submit an abstract for PhiusCon 2021 in New York.