Jarrod Denton has built what he calls his library of details.

Within these figurative records, the architect from St. Helena’s Lail Design Group holds the information he uses when completing a project. He tweaks these details, edits them, but for the most part, he just goes with them because he knows they’re efficient and knows they’ll work.

On a recent project, however, Denton didn’t visit his library. Instead, he threw out all the information he’s gathered and started from scratch. 

That’s the kind of thing that has to happen when designing the first certified passive house in California and the first passive house retrofit in the country.

“To have that clean slate to think about every component that goes into a house — it completely changes how I’ll look at things in the future,” Denton said. 

It also changed how he’d have to look at things back in January of 2009, when a former client of builder Rick Milburn of Solar Knights Construction in Napa — who Denton had worked with four times previously — got them in touch with Catherine O’Neill. 

O’Neill, who had recently retired after spending 25 years as an institutional trader on Wall Street, wanted a home that would make a sustainability statement for future generations.

That’s where the passive house concept came in.

“The concept is supposed to be very simple,” Denton said. “Over time, we’ve come to rely on technology to overcompensate for some of the inefficiencies we’ve tended to migrate toward. This is circling back in time, looking at the principles people have been doing in architecture for thousands of years.”

Following these principles leads to a much more energy-efficient home. Passive house buildings combine high levels of insulation with efficient windows and airtight construction, among other things, creating a sealed “envelope.”

The result? In the case of the O’Neill passive house in Sonoma — and in the case of passive homes as a whole — a residence that reduces energy usage by up to 90 percent of a traditional home. 

O’Neill’s energy bills are anticipated to be $20 per month or less. The home will be modeled by the Department of Energy through the Building America program.

“It’s all about the whole being greater than the sum of its parts,” Denton said. “If I were to just add any single component of the passive house, it’s not going to work. It’s the combining of them together that has made the product so much better.”

The product wasn’t easy to create, though — it was one of the most challenging passive house retrofits you could imagine, Denton said. He and Milburn were charged with renovating the existing Sonoma home, which was constructed in 1960. 

Originally, the house was two structures linked by a covered breezeway, resting atop a concrete slab that’s constantly radiating coldness. 

The new design, however, updated the two existing structures and converted the breezeway into a framed kitchen. This improved comfort, air quality and energy efficiency. The temperature inside the home is constantly between 68 and 74 degrees, even with the concrete slab still in tact. 

Alongside Denton and Milburn, passive house consultant Graham Irwin of Essential Habitat Consulting, Sonoma interior designer Jann Blazona and Jennifer Chandler of Chandler and Chandler Landscape Architecture in Napa all played key roles in the retrofitting process as well. 

“It was a very collaborate effort with this team,” Denton said. “The energy on this was just great. … This is the most fun I’ve ever had on a project.”

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The project required a 15 percent increase in material costs to move the O’Neill home from normal to passive standards, Denton said. For a new construction, the target number would be around 10 percent.

“That’s for a single-family residence,” Denton said. “If the conversation goes toward a commercial sector building, we’re shifting even further down. In Europe, the multi-family homes are being done for almost zero cost increase. For single-family residences, they’re probably targeting around 5 percent just because they have a lot of products there on the market.”

Denton said that more than 70 percent of the products used in the O’Neill house were made in America. He added that the O’Neill house would take eight-and-a-half to nine years for its return on investment.

Milburn said that these passive house concepts will become the cornerstone of sustainable building in the United States. 

“It already is in Europe,” he said. “We don’t have to go through a long, convoluted learning process — the Europeans have already done it for us. We have the opportunity to just take what they’ve learned and run with it.

“It’s kind of a quantum leap. You have these times in history where you meet up with a technology that answers the problem, and passive house does that.”

Denton agrees, calling passive houses “the only way to go.” Additionally, he said that by the year 2050, more 90 percent of existing structures in California will still be with us. For Denton, this makes the retrofit process all the more intriguing as a potential energy solution. 

“We look at housing structures in America and say, ‘Hey, in the next 10 years, let’s be 10 percent more energy efficient,’” Denton said. “That’s not going to make a difference. What this is doing is 80, 90 percent. That’s going to make a difference. That’s something you can actually chart and prove. The bigger picture — that’s something that excites me even more.”

“A lot of builders are pretty leery of green building now, because so much greenwashing is going on,” Milburn said. “They’re asking, ‘Hey, are we really affecting anything by doing this?’ What I would say to any builder out there is that passive house is very simple to do. It takes a little education, but it makes perfect sense to somebody who’s built buildings before.” 

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