475’s Year In Review, Part 3: Aaron McCormack on Wildfires, Climate Change and Building Better

475’s Year In Review, Part 3: Aaron McCormack on Wildfires, Climate Change and Building Better

As so many of us are working from our own pods and bubbles this year, 475 is reinventing our annual year-in-review post into a blog series with each post written by a different member of 475’s Sales Team reflecting on stories and trends in their territory.

Part 3 is by Aaron McCormack, 475 Technical Engineer and Materials Consultant working with projects across North America from the Brooklyn HQ office.

I've been lucky enough over the last 8 years to be involved in some way on high-performance projects from Ireland and the UK to all throughout North America - from Alaska to Texas, New York to California, and all the different climate zones in between. 2020 may go down in the record books as the worst, EVER! But amongst all the madness of this year, one unicorn that came my way is one of my favorite projects to have ever been a part of. Conveniently, when Brian and Jodi Abbot decided to downsize and simplify their life with a move to the Rocky Mountains, well known Passive House architect Andrew Michler turned out to be their new neighbor. An ideal pairing to commission Colorado's first Passive House Plus building.

Retiring from a career in video production, Brian heavily documented their entire experience. From YouTube videos to Instagram photos, their entire construction experience is there for everyone to witness so it was no surprise to see their project featured on the Discovery Channels Building Off the Grid (Season 10 Episode 1 if you're looking for it). Selfishly, I love this project for the product images Brian and Jodi produced using the beautiful backdrop of the Rocky Mountains.

Given the ecological nature of the build, architect Andrew Michler had to be defiant when it came to the building inspector signing off on the roof assembly. Building code dictates the use of air-impermeable insulation under sheathing on unvented roofs. These words hint and encourage the use of spray foam. Andrew, like us, does not find foam appealing (do we even need to state why?). With the help of a little venting, a quick WUFI analysis, and some discussion with the code official, a foam-free roof with cellulose and INTELLO Plus got the rubber stamp of approval.

Detail of the I-Joist Outrigger wall as shown in 475's Smart Enclosure ebook

Almost identical to our I-joist Outrigger Smart Enclosure system, the wall assembly is an uninsulated 2x6 service cavity with taped OSB as the primary air barrier. Outboard of that is the 16" Larson truss full filled with dense-packed cellulose. The WRB and insulation netting was installed next in the form of SOLITEX MENTO.

The initial airtightness figures came in at 0.74ACH, 4 times more airtight than the 3 ACH 50 required by the building code. As impressive as that was it still wasn't quite enough to meet the Passive House standard of 0.6 ACH 50. After knuckling down and searching out those leaks they managed to achieve an amazing 0.12 ACH 50, one of the best blower door tests I've ever seen! That's 25x better than the building code and 5 times more airtight than the Passive House requirement. The primary air barrier was INTELLO Plus on the roof and OSB sheathing taped with TESCON VANA on the wall but when you look at the details it's not surprising how good a rating they ended up getting. Little things like taping the edges of the OSB on all the window bucks, a secondary air barrier of SOLITEX MENTO on the outside wall with dense-packed cellulose, and ADHERO fully adhered on the roof, all contribute to this great blower door result!

But as 2020 would have it, all was not plain sailing. The early experience of bears trying to enter the building site turned out to be the least of their worries compared to what this summer brought. Brian and Jodi's story is ultimately a tale of narrowly avoiding complete disaster dealing with wildfire and smoke. While over a thousand structures were destroyed in this year's fire, some of which were homes of their own neighbors, this beauty managed to survive. The AB Passive House was completely surrounded by fires at one stage leading Brian and Jodi to evacuate their home. A total of 1,070 fires occurred in the Colorado mountain fires this year across 625,000 acres of land. Saddest of all, it resulted in the loss of two lives.

Thankfully, Colorado's largest wildfire on record is now fully contained and Jodi, Brian, and the AB Passive House are safe and sound currently embracing Colorado's winter snow. Watching Jodi and Brian's experience and struggle on social media really highlighted the drastic effects of climate change and just how important a role Passive House has to play in the battle against it. It’s a reminder to me that in the face of challenging situations and near-complete disaster, we need to move ahead in a positive direction - it’s the only way to go.

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