Written by: Casey Law and Kathryn Soter | GFDA Contributors
During a dry and windy late December day, two small grass fires ignited in the foothills of the Flat Irons, Boulder, Colorado’s iconic mountains. In normal conditions, these fires would have been quickly extinguished. Unfortunately, the year would end up being anything but normal for a small bedroom community called Marshall.
In 2021, a very wet spring, followed by a very dry summer and fall, yielded an overgrowth of dry grasses and plenty of fuel for wildfires, a condition all too familiar for those of us living in the West. On December 30, the Boulder area experienced 115 mph winds that fanned the embers across the arid lands from rare weather phenomena. The Mountain Wave effect—first discovered in the 1930s by a couple of German glider pilots—can result in hurricane-force winds combined with an unusually prolonged duration. The fire blew like this for 11 straight hours.
The next day, a heavy snow put out the fire and the shock set in. The fire burned 6,000 acres of land, destroyed 1,084 homes, killed two people and thousands of animals, marking “The Marshall Fire” Colorado’s most destructive wildfire to date.
L to R: The original wood-frame house; devastation after the fire; new resilient construction
A retired software engineer, who lost her home in the fire, had lived there since 1985, drawn to the property more by the stunning vistas than the rather quirky wood frame home that came with it. It was situated on a bluff just outside Marshall, more open prairie than wooded enclave, which made it more puzzling that her house caught on fire—the only one in her neighborhood to burn down completely.
Devastation soon gave way to determination and the homeowner decided to rebuild a more resilient home and landed on a Passive House Design. These homes are highly energy efficient but she felt its construction would be more resistant to catastrophic weather events like The Marshall Fire. When asked why she wanted to rebuild “passive,” the homeowner answered without hesitation, “Because of the state of the world.” She also had other priorities for the home besides being energy efficient and fire resistant. This is her “forever home,” so it was specifically designed for aging in place, which is why they chose a one-level home with a simple floor plan. And because she shares her home with her cats, she wanted the home to be hypoallergenic so the indoor air purification system was ideal.
Her research led her to Cottonwood Custom Builders, led by Jeff Hindman, one of Boulder, Colorado’s most esteemed green home builders and remodelers. This past spring, the Good Future Design Alliance visited the home, as construction was nearing completion, to learn more from the team at Cottonwood, Kaitlin Belyea, project manager, and Chris Sommers, production supervisor.
35% of global energy consumption is driven by the heating and cooling demand of buildings.
The team from Cottonwood (Hannah Finch, Chris Sommers, Kaitlyn Belyea) pose with the homeowner outside her nearly completed new home.
You might be wondering what exactly is a “Passive House”and why it is called that. The term, “passive house” refers to a housing standard that maximizes passive energy inputs like sunlight and heat recovery, to heat the house naturally, rather than active heating and cooling systems, which are energy intensive. Unlike a conventional building, passive homes must meet certain standards defined by the International Passive House Association.
Key elements of a Passive House include:
- A thoroughly insulated exterior
- Airtight walls to prevent leakage or drafts
- High-performance doors
- Low emissivity windows to minimize heat loss
- Ventilation to ensure good air quality
- Strategic house orientation and window placement to optimize heat from the sun in colder months
- Strategically placed trees, awnings, shutters, etc. to optimize shade in warmer months
This was their first Phius Passive House project, so the team at Cottonwood was rigorous in their attention to detail to implement these standards. To make the new home more resistant to wildfires, protective materials such as gravel moats were used around the home.
“I’ve never seen a house pass its first time. If you do, I‘ll be really impressed.”
— Quinn Steadman, energy rater
Passive House Design uses 90% less energy for heating and cooling than conventional buildings, making them a more energy and cost-efficient alternative in the long run. According to Wayne Turett, of Turett Collaborative, “Passive House design is gaining momentum as an approach toward achieving net zero construction.”
We blew through the Blower Test!
CCB engaged a professional energy assessor to conduct blower door tests to help determine how well the insulation keeps out air leakage. The Cottonwood team said, “This was taking insulating a home to a whole new level!” But true to their reputation, not only did the house pass both the pressurization and depressurization blower tests, but it passed on the first attempt, and by a margin much better than code compliant, something Quinn Steadman, the energy rater, said she rarely has seen.
Quinn Steadman prepares the blower test.
Curious about whether Passive House construction is right for you?
Building new or remodeling your home presents the perfect opportunity to embrace cutting-edge, sustainable living. By reading up on passive housing, and hiring experts to execute your vision, you can create an energy-efficient, resilient house that will stand the test of time…and mother nature.
While it may be more costly upfront to build a Passive House, this type of construction is built with such high-quality products and strategic orientation, that passive houses, in the long run, require less maintenance and cost less to operate than conventional buildings. That’s because they maintain thermal temperature more efficiently year round.
Here are a few other things to note as you start your research:
• Conventional ventilation or heating and cooling systems can be modified into passive systems.
• Although passive systems can technically be built almost anywhere, depending on the type and extremity of the weather in your area, they could require additional adjustments to meet the rigid criteria.
• Extensive modification can be costly, however, upgrading an existing building to a Passive House can reduce waste generation, lower greenhouse gas emissions, and help support a better, more sustainable, future.
To learn more, contact: https://www.phius.org/passive-building/what-passive-building/passive-building-faqs, https://www.iea.org/energy-system/buildings, and https://www.passivehouse-international.org/
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