With contributions from a pair of Phius project teams, this blog examines fire resilience considerations in passive projects and the role of Phius design strategies in mitigating fire risk.
With the impacts of the devastating Los Angeles wildfires top of mind, our hearts go out to all of those impacted. There has been significant discussion regarding the role passive building design plays in wildfire resilience, and we would direct you to our statement on the topic for more information.
In this blog, however, we spotlight two Phius projects that were constructed with a focus on fire resilience, one of which was a wildfire rebuild. Hear from the project teams below.
When I received the initial call for a new residential project in Santa Rosa, California, the conversation began in a fairly straightforward manner, much like my initial calls with many prospective clients. However, when the husband and wife owners – who both work in tech – asked about airtight construction just a few minutes into the conversation, I knew this was not going to be a typical project.
This couple had done an enormous amount of research on the U.S. The Department of Energy’s Zero Energy Ready Home program, had developed a deep well of knowledge about high-performance homes, and were 100 percent committed to building an energy efficient house as their forever home. Though they had not been exposed to passive building principles, it was obvious that their aspirations were aligned with Phius goals, and very quickly they were on board with creating a home that would meet Phius passive building standards.
The property they found was located in the Fountaingrove neighborhood of Santa Rosa, directly in the path of the Tubbs Fire of 2017. Their new house would replace a home that burned to the ground in that fire. Though passive building design is not a replacement for fire-safe design and construction, the overlap between energy efficient, airtight design and fire-resilient design and construction methods is significant, and the benefits are universal.
Our clients, who had two children during the course of design and construction, had a real budget, and their home has a modest footprint of 3,100 square feet. The home we devised together is aspirational in energy-efficiency and fire resistance, but eminently achievable both in scale and cost, making it a valuable model for others in similar circumstances.
This project brought together a team that was not only skilled, but eager to grow and advance in their knowledge and understanding of passive building principles and technologies – an all-too-rare example of a project where every team member was fully dialed in.
It started, of course, with clients who knew nearly as much about building science as most building professionals I know. They came to the project with a conceptual design conceived, adjacencies established, systems goals laid out, and a list of products in mind. The husband is a computer programmer with a systems mindset, and he gave us an operations manual from day one.
A high-performance build played a role in our clients’ plans from the outset. After preliminary pricing and 100 percent schematic design, the owners and architect worked to find a loan that would allow them to incorporate the passive building standards they planned to incorporate into the design to their advantage. The team needed to establish the proper valuation for the project they were undertaking, which would incorporate the benefits of the passive building technologies on the value of the completed structure. Fortunately, the owner found and forged a connection with a bank that understood the inherent value of passive building design and construction, an all-important first step in the development of the project.
While passive building technology is not a replacement for fire safety measures, there is a significant overlap between structures that are resilient to fire and those that are airtight and designed to passive building standards.
Here are some of the ways in which the design of this project enhances – though it does not assure – fire resiliency:
With two small children and jobs that enable them to work remotely, the clients for this project spend more hours in their home than any of my other clients. They are optimizing the value of the real estate by using more than the typical owner, and the benefits of enhanced air quality and energy-efficiency increase accordingly. We designed the home office, which they share every day, with purposely designed cross ventilation and three times more fresh air than average.
When our clients selected the location of their home, they did so after a deep and thorough analysis of their needs and the opportunities afforded by numerous locations around the country. They had done their research and understood that they could build an energy-efficient, airtight home that would also be more resilient in a fire-prone region. They could live their values, maximize their experience of the home and mitigate their risks, because the whole team shared deep knowledge of the area, understood the technology and methods, and were aligned about the project’s parameters and goals.
By Jon Alexander and John Novak
This Phius project was built on a steep forested hillside about a 20 minute drive east of Seattle. The owners came to the architect with the goal of obtaining passive building certification and making the most of the beautiful southern views the site had to offer. A large covered, all-seasons deck connects the western garage/outbuilding wing to the east main house wing.
Easily achieving net-zero energy with a 17 kW PV array and 40 kWh of backup batteries, this all-electric home is heated by a very energy efficient CO2 SanCo air-to-water heat pump. Large south overhangs and little east and west glazing helped keep air-conditioning demand to a single-head unit located in the center of the house.
Ventilation is provided by a Zehnder HRV which is connected to an Airwash Whisper Filtration System with dedicated HEPA and carbon filters. Its HEPA filter is rated to filter 99.97% of particles >.3 microns, filtering out the very fine particles that make wildfire smoke so hazardous. This filtration system is capable of maintaining high indoor air quality during major wildfire smoke events.
This two-level home is sided with pre-burnt wood, Shou Sugi Ban T&G boards from Nakamoto Forestry – a beautiful low-carbon material. The top and bottom of this vented rainscreen cladding is protected from the entry of fire embers by a durable stainless-steel mesh.
The main roof surfaces are standing seam metal, ventilated from below. Vulcan Vents in the eaves help to ensure that fire embers don’t enter the roof system. A high proportion of homes that burn during wildfires are ignited by blowing fire embers. All soffits are sheathed with fire-rated Densglass.
All trees within falling distance of the house were removed as well as a significant portion of the trees downhill from the house. The area immediately adjacent to the home is kept clear of vegetation and other flammables.
During design and construction, other fire-resistant measures were discussed but ultimately abandoned due to aesthetic and/or cost considerations. The fire risk in this vicinity was relatively low historically but has increased and is likely to continue increasing significantly. It’s very important that we build homes that are prepared for and can adapt to the significant changes they are likely to encounter in the future from climate change.
The extensive O&M manual was created for this home outlines additional steps and resources to further reduce the risk from wildfires, which include:
