flexiblefullpage - default
Currently Reading

Net Zero Energy: The Ultimate Z.E.N. Home's Wall Assembly

Advertisement
billboard - default
Construction

Net Zero Energy: The Ultimate Z.E.N. Home's Wall Assembly

The Ultimate Zero Energy Now Home proves there’s more than one way to deliver a high-performance wall


By Charlie Wardell April 2, 2020
Ultimate ZEN Home high-performance timber-framed wall assembly for net zero energy
The home’s double 2x4 wall stud system, separated by a 2 1/2-inch air space, will be insulated with blown fiberglass and air-sealed at the drywall, but will not have exterior insulation board. | Photo: Thrive Home Builders
This article first appeared in the April 2020 issue of Pro Builder.

With energy codes likely to mandate some version of net-zero ready energy standards for new construction within a decade, many building science experts believe every home will soon require exterior insulation board to deliver an optimum perimeter wall system.  

Others agree with the science, if not the mandate. One is Thrive Home Builders, in Denver, which is partnering with Pro Builder and the Energy and Environmental Building Alliance (EEBA) to build The Ultimate Z.E.N. (Zero Energy Now) Home. 

While the 2,500-square-foot model home will showcase several building innovations, Thrive chose to build a staggered double 2x4 stud wall system that some may consider regressive (see details in photo, below).

In fact, the assembly affords Thrive several advantages: familiarity among framing crews; relatively simple flashing details at openings; and an air space that provides a thermal break. Best of all, the wall achieves an insulating value of R-40 without using petroleum-based exterior insulation board, reinforcing Thrive’s commitment to more sustainable building practices.

Thrive CEO Gene Myers adds that homeowners love the deep window wells afforded by the 9 1/2-inch-thick walls. “They’re a constant reminder of how highly insulated the home is and have become a bragging point for many owners,” he says.


RELATED


Why the Bad Rap for Double Walls?

Still, double walls get a bad rap because many fear that, with so much embedded R-value, the inside face of the structural sheathing (in this case OSB) will get cold enough in winter for moisture to condense in the wall cavity. In fact, building scientist Joe Lstiburek has advised against a double-wall assembly unless there’s also sheathing on the outside of the inner wall to keep moist indoor air from condensing on the inside face of the exterior sheathing panels, a recommendation that kills any cost advantages of the double-wall scheme

Myers understands the science, but insists that Denver’s dry climate nullifies such moisture concerns. He admits the system likely wouldn’t work in cold, damp climates, such as New England, though Maine builder Dan Kolbert has found nothing that would indicate a problem after testing several double-wall homes for temperature, relative humidity, dew point, and wood moisture content over several years.

Ultimate ZEN Home high-performance wall assembly framing
The Ultimate Z.E.N. (Zero Energy Now) Home uses a a staggered double 2x4 stud wall system some consider regressive, but the assembly affords several advantages. | Photo: courtesy IBACOS

 

The Sweet Spot for Wall Performance and Cost

Even so, Thrive went to great lengths to vet the wall design, running various iterations through HERS (Home Energy Rating System) and Passive House software to find the sweet spot for performance and cost. Because the offset 2x4 studs are 24 inches on-center, Thrive also worked with an engineer to make sure all loads would transfer properly. And the project’s insulation partner, Owens Corning, conducted a moisture simulation to confirm there would be no issues in Denver’s climate.

For The Ultimate Z.E.N. Home, innovation isn’t necessarily about rejecting old ways but of scrutinizing and upgrading them as necessary—a theme you can expect to continue as Pro Builder follows the home’s construction in the months ahead and when it opens for tours during EEBA’s annual summit in September

 

Ultimate ZEN Home partner companies' logos

 

Access a PDF of this article in Pro Builder's April 2020 digital edition

 

Related Stories

New-Construction Projects

A Near Record Number of Housing Units Are Under Construction, but They’re Taking Longer to Complete

Single-family housing starts are rising, but supply-chain delays are pushing back completions

Construction

How Much of a Home's Sales Price Consists of Construction Costs?

Construction costs accounted for more than half of a home's total sales price in 2022

Labor + Trade Relations

Construction Job Openings Fell 50% From December to January

A 50% decline in construction job openings has the industry's leading economists scratching their heads. Here's what may be driving the sudden slowdown

Advertisement
boombox1 -
Advertisement
native1 - default
halfpage2 -

More in Category




Advertisement
native2 - default
Advertisement
halfpage1 -

Create an account

By creating an account, you agree to Pro Builder's terms of service and privacy policy.


Daily Feed Newsletter

Get Pro Builder in your inbox

Each day, Pro Builder's editors assemble the latest breaking industry news, hottest trends, and most relevant research, delivered to your inbox.

Save the stories you care about

Lorem ipsum dolor sit amet lorem ipsum dolor sit amet lorem ipsum dolor sit amet.

The bookmark icon allows you to save any story to your account to read it later
Tap it once to save, and tap it again to unsave

It looks like you’re using an ad-blocker!

Pro Builder is an advertisting supported site and we noticed you have ad-blocking enabled in your browser. There are two ways you can keep reading:

Disable your ad-blocker
Disable now
Subscribe to Pro Builder
Subscribe
Already a member? Sign in
Become a Member

Subscribe to Pro Builder for unlimited access

Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.