1.) The San Francisco Bay Area is Primed for Passive House
The energy at the conference was palpable. The Bay area has so many opportunities and resources focused on nudging the building community toward high performance and Passive House construction; it seems the scene is about to enter a new phase of development.
The Bay Area, and Palo Alto in particular, has seen the first wave of Passive House early adopters come to fruition. We saw some stunning high performance houses on the PedalHaus tour – a bicycle tour of 13 different Passive House projects in one community. Homeowners on this tour attested to the fact that Passive House can be reached for less than standard cost of construction per square foot in area. There are abundant resources and support from Passive House California, CertiPHIers, and regional design firms like Clarum Homes (who retrofitted their own office to Passive House standards).
In preparation for the trip, we ran a number of different possible wall and roof assembly scenarios for the region to assess vapor drive and moisture safety. In doing so it became apparent that coastal California can achieve high performance with airtightness, simple 2×6 or even 2×4 details, and a small amount of continuous insulation outboard of the studs. We found safe envelope scenarios, even using traditional stucco exteriors without a rainscreen, as long as INTELLO Plus is providing airtightness and smart vapor control inboard.
In the Bay Area, average temperature changes are not drastic from season to season, so daily temperature swings are the bigger driver of space heating and cooling. This is something directly addressed by Passive House levels of airtightness, which allows you to maintain comfortable indoor temperature for multiple days – even in the rare cases of extreme cold.
2.) Literally Zero Insulation in Many Buildings
None. Zero insulation. This is common knowledge to some, but I was not aware that many buildings in the Bay Area were not built with insulation, or were built with whatever they could stuff into the walls while the region built up throughout the 20th century. Retrofitted buildings are required to install some, but I hear that requirement is not strictly adhered to. I stayed with a friend in Oakland in a home with zero insulation, and can describe the feeling to be akin to a wooden tent – complete with condensation on the inside walls and windows in the chilly hours of the morning. Continuing my thoughts from above, I think this can be a great opportunity for the area. A truly consistent and comfortable indoor environment is enviable to those with nothing but drywall and siding between their bedroom and a dewy 45°F morning. An added benefit: when you do retrofit there is so much less to throw out. No old, moldy insulation or welded on, toxic, spray foam to scrap off and dispose of in your safety space suit. Just an open bay waiting to be warm.
3.) Californians Love Radiant Floor Heating
Something I have never heard before on a Passive House tour: “…so we decided on radiant floor heating.” Why do I never hear this? Because Passive House is all about reducing the size, the BTUs, and the expense of the heating and cooling system. Radiant heating is big, costly, and far more BTUs than needed. In fact, something you often hear from Passive House owners, is that their floors stay warm and cozy year round.
So why do Bay Area Passive House owners use radiant floors? The answer is: they actually don’t. Even the ones who install it, don’t use it. I heard a homeowner say they warmed it up for about a week out of the year. Sunshine through the windows act as the floor warmers, and little more is necessary. I chalk it up to lessons learned in the first wave of early adopters to the region. Radiant was a great heating system for their previously uninsulated home. And if you’ve never had the experience of comfortable surface temperatures in a house in the dead of winter, it’s hard to believe you’ll get there without burning some energy. Just imagine how low the cost per square foot of construction can go once you swap out the heating system with something sized closer to the tiny heat demand, like heated towel bars, or maybe just a high energy puppy.
4.) The Rent is High – Go Tiny
A fantastic family of architects built a tiny house on a trailer which was displayed in mid-construction outside the conference. The husband and wife team of dimensionStyle is the Passive House design and construction duo, Brian Rubin and Siena Shaw. They call their latest project the MightyHouse. And it is a test lab for building science, systems, and materials. It’s not about points, performance statistics, or certifications, it’s about comfort, health, and building the right way. One of their goals is to demonstrate Passive House principles on a budget, managing the astronomically high cost of land in the area by simply not buying land. Brian tells me “the MightyHouse (currently under construction) is a mini rolling passive house with a projected cost of $32,000, roughly $120 per square foot.” In a city as unrelentingly beautiful as Palo Alto, making the world outside your door into a living room seems a great option.
MightyHouse is one of the most carefully considered tiny house details I’ve come across. For those interested in this newly popular building design, there are a few hurdles unique to tiny house projects. Determining a structurally sound connection to the giant metal thermal bridge of the trailer is a major detail yet to be completely settled. If anyone knows of a project that has an elegant solution to this, we’d love to hear it in the comments below. MightyHouse is bolted directly to the trailer, opting to insulate over each bolt on the interior.
Finding an appropriately-sized and affordable HRV for such a small space is a problem with a solution; the Lunos e² has been used by dozens of tiny house builders as a means for continuous ventilation with heat recovery. MightyHouse is planning to install a Lunos, and other examples include the Leaf 3, Artisan Tiny House, and the Runaway Shanty< project.
5.) When It Comes To Building Materials, You Can Have It All: Health + Performance + Sustainable Source
We were excited to give our newest presentation at Building Carbon Zero California, which we call Toward Safe and Natural High Performance (register now for the webinar of this session, happening Dec 8). In this talk, we focus on how to choose building materials that provide the high performance you want without detrimental health impacts, high global warming potentials, or relying on sources that are non-renewable. Some of the research we did for the presentation opened our eyes to the wide variety of sources that exist to provide solid information to help you make informed choices. You may have noticed some of these sources, already popping up on our blog. This includes the Declare Label program from the International Living Futures Institute, the Pharos project of the Healthy Building Network, or the Sentinel Haus based in Frieburg, Germany.
One finding of particular interest – phosgene is one of the many chemicals we call out as an ingredient of spray foam. It turns out Phosgene was used as a chemical weapon during World War I. The warning poster (pictured right), designed a century ago to alert soldiers to the existence of this threat, is an excellent reminder of why we should eliminate spray foam from our building practices. It just doesn’t make sense to spray a potential chemical weapon in our buildings!
6.) 475 is Officially Bi-Coastal
We got our start on the East Coast, and currently have our largest collection of friends, customers, and connections in the Northeast. So, I was very excited to hear so many people on the West Coast mention our blog and our knowledge resources. Thank you for reading!
We now have a West Coast warehouse in the Portland, Oregon area and our new Seattle-based Product Consultant, Lucas Johnson. We’re looking to greatly expand our knowledge base to more prominently include information on climates in the West, and to address construction and design issues particular to buildings on the Pacific side of the continent. Building Carbon Zero California was great success, and a joy to be a part of because it exemplified the reason we need events like this: to share experiences across regions and build on knowledge that allows us all to grow.
A big thanks to all who organized the event, and all who attended. We’ll plan on seeing you all at the next one!