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Refuge From the Storm

Resilience is another reason to build Net Zero Energy homes

Refuge From the Storm

When winter storms put the lights out in Matt Coffey's neighborhood he doesn't worry. "My house can stay in a comfortable temperature range for days," he says. That's because his 3-bedroom zero energy Cape-style home combines a high-efficiency building envelope and HVAC system with rooftop photovoltaic panels.

Coffey is one of five staff architects with South Mountain Company (SMC), an architecture, building, and energy firm West Tisbury, Mass. The company is one of a cadre number of builders who realize that while energy-savings and healthy living remain the top selling points for high-performance construction, these homes can also be made resilient enough to keep going when the power goes off.

Resilience in the face of weather events and power outages could shape up as the cutting edge of performance building. It's a benefit that builders of Net Zero Energy homes can easily offer with just a few adjustments.

And outages are a fact of life. Hurricanes, tornadoes, blizzards ice storms, wildfires and other weather incidents that threaten the power grid seem to make the news, weekly. This March, for instance, 2.8 million people in the Northeast and mid-Atlantic found themselves without power after a nor'easter blew across the region. Six months earlier, hurricane Irma had put 7.6 Southeast residents in the dark, some of them for a week. If the weather weren't reason enough to take resilience seriously, policymakers now worry about terrorists taking the grid down with a cyber attack.

Every problem comes with an opportunity, and the opportunity here is that a high-performance home is by nature more resilient in the face of these threats than one built to code standards. As homeowners grow more anxious about the effects of nature's wrath, making them possible to stay home with minimal discomfort during an outage will give the builder an added edge.

Beyond Green

At the core of a resilient home are well-established sustainable design features that high-performance builders already include in their homes. "Many of the strategies needed to achieve resilience, such as really well-insulated homes that will keep the home habitable if the power goes out or interruptions in heating fuel occur, are exactly the same strategies we have been promoting for years in the green building movement," says Alex Wilson, president of the Resilient Design Institute in Brattleboro, Vt. "The solutions are largely the same, but the motivation is one of life-safety, rather than simply doing the right thing."

Wilson believes that this life-safety aspect of green building will appeal to a wide market, and could help accelerate acceptance with mainstream builders and homebuyers.

For builders already delivering Zero Energy Ready homes, the good news is that true resilience is the next logical step. "A house that achieves net-zero-energy performance with a modest-sized solar array, say less than 6 or 8 kW, is probably well enough insulated to be 80% to 90% of the way there," says Wilson "It is not that hard to take the next few steps." (RDI's website includes several articles on how to do that.)

While SMC builds custom homes, this approach has also been embraced by some production builders. One of this is Thrive, a Denver company that will close 240 homes this year and that recently made rooftop solar electric panels and backup batteries standard equipment. If a blizzard takes down the power lines, the battery and solar panels will keep some lights, the refrigerator/freezer, and the furnace or heat pump going for long enough each day to keep the home habitable.

Thrive was able to offer this benefit because it was already building Net Zero Energy Ready homes that lose heat very slowly when the power goes off. "We decided to make Zero Energy part of our company brand," says CEO Gene Myers.

Setting Priorities

While many builders don't include backup power, a home has to achieve minimum performance baseline to be considered resilient. In cold climates like those where SMC and Thrive build, the absolute minimum is a home that, during an outage, will stay in a comfortable temperature range for several days during winter with no power at all.

In areas subject to severe storms, such as on the Atlantic coast, resilience also includes a near-obsessive level of waterproofing—a wet and moldy house isn't one people will want to stay in. One builder who understands this is Jim Schneider, who builds in Virginia Beach where horizontal, wind-driven rain is common. "The envelope absolutely has to be tight," he says. That means staying current with the latest flashing details, which he says manufacturers and building scientists are constantly refining. "Building science has evolved quite a bit in recent years so you really need to make a commitment to keeping up with it."

If you want to include solar panels and a battery you need to size them. More capacity equals more money so the decision usually depends on the client. "If the home gets its water from a well you at least need enough power to run the well pump," says Coffey. "Beyond that, some people are happy with a form of at-home camping, while others want to have every amenity no matter what happens."

Coffey also says that the most resilient homes replace combustion appliances with electrically driven ones. "A solar system can keep an electric water heater and space conditioning system going indefinitely."

Dollars and Cents

Taking steps toward resilience doesn't have to inflate the budget, which is why some affordable builders are doing it. According to Tiffani Irwin, director of construction at Our Towns Habitat for Humanity in Charlotte, NC, a lot of affiliates have committed to building affordable, zero-energy homes. The cost to get there varies, with the biggest variable being what state and local building codes already mandate. "If you're building a code-level house in Oklahoma it will cost more to get there than if you're building the same house in Maryland which has a stricter energy code," she says.

And while the first few homes can require the builder to invest some serious time in design and engineering, the process gets easier with each project. Most builders quickly settle on a suite of cost-effective details they can use on any project.

The biggest secret to keeping costs down, according to Irwin, is careful design and engineering. That includes pre-construction modeling to calculate the projected energy savings and the payback for the homeowner. "Builders need to develop a rapport with a good rater then work closely with that rater," she says.

Of course, that's something all builders should be doing.

For builders interested in learning more, EEBA's annual Summit will focus on Zero Energy construction and Resilience in the Built Environment. Go to summit.eeba.org.

 

Caption: One hallmark of a resilient home is a high-performance building envelope. Here, workers are protecting the WRB and beefing up wall insulation by covering it with a foam-and-OSB nailing base for the siding.

Photo Credit: South Mountain Company

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