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Musings of an Energy Nerd

Designing a Multifamily Building That Approaches Passive House Performance

Architect Jesse Thompson shares lessons he’s learned from three recent projects

A high-performance multifamily building needs a good balanced ventilation system. At the Bayside Anchor project in Portland, Maine, the architect specified one Renewaire ERV per floor.

Jesse Thompson is a Maine architect whose company (Kaplan Thompson Architects) has been involved in three recent high-performance multifamily projects. At the Better Buildings by Design conference in Burlington, Vermont, on February 6, Thompson shared what he’s learned with an attentive audience of designers and builders.

Thompson has encountered plenty of owners who shy away from the Passive House approach out of fears that meeting the stringent standard will lead to high construction costs. When that happens, Thompson sometimes manages to slip high-performance targets into the project specs without explicitly notifying the owners. The happy result is that the project ends up performing almost as well as a Passive House project. Thompson calls this approach “stealth Passive House.”

For me, the important takeaway from Thompson’s presentation was this: With multifamily projects, airtightness and ventilation system efficiency matter more than insulation R-values.

The first multifamily project that Thompas discussed, Bayside Anchor, was a Passive House project certified by PHIUS. The second, Blackstone Apartments, was a high-performance project that wasn’t explicitly aiming for Passive House, but got most of the way to Passive House performance.

The third, Parris Terraces, is a project spearheaded by a for-profit developer who was unwilling to make a full commitment to the air sealing details required to achieve high performance.

Located in Portland, Maine, Bayside Anchor is an affordable housing project funded by the low-income housing tax credit program. The four-story 40,000 square foot building has 45 apartments. The budget came in at $170,000 per unit, including land costs and site developments costs. That’s $142 per square foot.

Bayside Anchor

The architects promised the owners that the new building would meet the Passive House standard. According to Thompson, achieving that goal required many “long, intense team meetings that each lasted three hours.”

Here’s what the team ended up…

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9 Comments

  1. User avater
    Stephen Sheehy | | #1

    Parris Terraces has 23 units, not 7, all one bedroom, all between 400 and 550 square feet.

    1. User avater GBA Editor
      Martin Holladay | | #2

      Stephen,
      Thanks for the correction. I have edited the article. I appreciate it.

  2. Doug McEvers | | #3

    Great article, I appreciate the square foot costs for the 3 builds. Energy efficient building is affordable.

  3. Malcolm Taylor | | #4

    Projects like these make a huge difference. Kaplan Thompson seem to just move from strength to strength. great role models for us all.

    1. User avater GBA Editor
      Martin Holladay | | #5

      The architects at Kaplan Thompson don't just follow the safe and narrow path -- they are trailblazers, and they re-define what's possible.

  4. Andy Kosick | | #6

    I really appreciate the stealth passive. Fact is, many aspects of building performance make so much sense you should just do them. People don't complain about things working better. Way to go Kaplan Thompson.

  5. Trevor Lambert | | #7

    One comment, one question.

    Who was the Canadian supplier of the wall assemblies for the Blackstone project, is that a trade secret?

    The lack of smell in the kitchens means nothing in regards to the health concerns of recirculating range hoods. My house smells great and fresh too, but five hours after cooking burgers the PM2.5 reading is still five times the recommended 24 hour average limit. That's measured in the bedroom, not the kitchen.

  6. Jaccen | | #8

    Great article showing real-world results (ie. cost per sqft).

    I, too, would be interested in the Canadian supplier.

  7. User avater GBA Editor
    Martin Holladay | | #9

    Trevor and Jaccen,
    Jesse Thompson has emailed me: The fabricator was Adam Lumber in Waterloo, Quebec.

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