Behind the Walls: VISION House at Mariposa Meadows

Behind the Walls: VISION House at Mariposa Meadows

Green Builder Media is making steady progress toward building durable, resilient and energy-efficient structures in Colorado’s high country.
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VISION House at Mariposa Meadows

Green Builder Media

Green Builder magazine Managing Editor, Juliet Grable

Friday, October 16, 2015 - 8:30am

CAMPAIGN: VISION House at Mariposa Meadows

CONTENT: Article

Compared to the rest of the country, it’s been a quiet fire season in Colorado. The wet spring weather also produced a bountiful crop of wildflowers at Mariposa Meadows, Green Builder® Media’s ambitious VISION House® project in southern Colorado. Progress has been slow but steady, as the team lays the groundwork for what will eventually serve as the Green Builder® Media Sustainability Institute.

Two structures are up; a third is poised to follow early this fall. These first three buildings represent Phase I of the carbon-neutral compound, which will function completely independent of the grid. Eleven sustainability tenets guide the project, and although Green Builder® Media President Ron Jones and CEO Sara Gutterman are considering all of them from the outset, three—Energy Efficiency, Durability and Disaster Mitigation—are driving many of the early decisions around site development, building design and material choices.

“We’re taking a whole-building approach,” says Jones. “Because we’re off grid, we need to minimize demand. So we’re asking, what are the limitations and the opportunities?”

Working with SIPs and ICFs

These first three structures—Aspen Cabin, Atrium Duet and Studio—feature foundations made from insulated concrete forms (ICFs) and walls and roofs made from structural insulated panels, or SIPs.

ICFs consist of rigid polystyrene forms filled with concrete, which is reinforced with rebar. The forms can be adjusted to accommodate desired wall thickness. ICFs are strong, energy efficient and fast. Jones has worked with them since the 1970s.

“I’m a firm believer in ICFs,” he says. “One of the main advantages is that a few guys can handle quite a bit of material.” Using ICFs instead of a full concrete structure also reduces the total amount of concrete, which is expensive and difficult to deliver to a remote site such as Mariposa Meadows. Jones says an ICF foundation wall is the perfect complement to a radiant heat (hydronic) floor, as the airtight system helps contain the heat in the slab, making it more efficient. (All three of the initial structures feature hydronic floors served by Uponor PEX and powered by Bosch LP-fired boilers.)

But ICFs don’t need to be confined to foundation walls, says Murray Snider, vice chair of the Council for ICF Industries, or CICFI. In fact, they see their greatest energy efficiency benefits above ground, where they are subject to more extreme fluctuations of air temperature.

The R-value of the foam is 4.2 per inch, but R-values are inadequate for evaluating the whole ICF “sandwich,” says Snider. Because ICFs combine thermal mass with airtight, thermal bridge-free assemblies, it takes a long time for external temperatures to affect building interiors.

While Jones and Gutterman may use ICFs for complete buildings in the future, the first three feature ICF foundation walls and use SIPs for the above-ground walls and roofs.

The SIPs were provided by the Structural Insulated Panel Association, or SIPA. Working with SIPs required a learning curve, says Jones. “There’s a simple but detailed procedure to prepare. It also takes more machinery than conventional construction,” he says. “But it’s clear to me that if you have the equipment and an experienced crew available, it can really speed up the [building] process.”

Getting machinery to such a remote site was challenge enough, but there were also logistical issues on the site itself. The buildings are tucked against the side of a mountain, which means a crane cannot get around all sides.


CATEGORY: Environment