By Christopher Mims

In December 2021, Mark Attard's home survived the Marshall Fire -- the most destructive forest fire in Colorado's history -- virtually unscathed, even as neighbors' homes were rendered uninhabitable.

The director of operations at a small home-building company, Attard hadn't set out to make his house disaster-proof. But the energy-efficient upgrades he made over the years, including changes to make it airtight, sealed it against embers that ignited some of his neighbors' homes from the inside and the smoke that inundated many others. Almost immediately after the fire, "we walked into our house and we didn't even smell smoke," he says.

Attard had stumbled onto a phenomenon that is at the forefront of cutting-edge construction techniques. As architects and contractors turn to green technologies to make homes healthier and more sustainable, they are also finding it makes them more resilient against extreme weather and increasingly common natural disasters. With innovations in insulation, heat pumps and prefabrication, they're discovering that a home built to save the planet can also save itself from wildfires, high winds and deadly heat and cold.

The trend has roots in a movement called "passive house," based on a design standard to make buildings use as little energy as possible. This type of construction is booming as consumers and builders seek to prevent climate change and protect against its effects. Three million square feet worth of passive-house have already been certified in 2024, from 1.8 million in 2021, according to Phius, which certifies such homes.

That is likely to accelerate: Massachusetts alone has passive house projects under way totaling 22.6 million square feet. This isn't just about high-end, individual detached homes. The state has mandated that all multifamily dwellings larger than 12,000 square feet in and around Boston must meet the passive-house standard. In East Harlem, New York, the world's largest passive house-certified building, with 709 units, was recently completed for the New York City Housing Authority, and was designed by Handel Architects.

Like a Stanley water bottle

Passive-house technology is constantly evolving, but its elements make it possible for structures to maintain ideal temperature and humidity, have the healthiest possible air quality, and minimize energy consumption, says Cody Fischer, president of Footprint Development, which builds ultra energy-efficient apartment buildings in Minneapolis.

You can think of such buildings like the giant insulated Stanley water bottles that have become so popular, says Ken Levenson, executive director of the Passive House Network, a not-for-profit that teaches how to build such structures. The inside typically doesn't touch the outside except at the threads where the lid screws on, eliminating "thermal bridging" points where heat can easily travel in or out.

Similarly, passive homes minimize places where exterior cladding contacts interior materials. They also maximize the effectiveness of the insulation in walls and rooftops.

Achieving that with traditional building materials is challenging, if not impossible, says Fischer. New insulation technologies are making their way to the U.S. that can be cheaper, more effective, easier to use and more environmentally friendly, including wood fiber, foam made from renewable materials, low-carbon concrete, and a substance called hempcrete, which is a lightweight, biodegradable composite of lime and ground up hemp plants.

Then there are some truly radical solutions, including a system from Miamisburg, Ohio-based Aeroseal that works like a Fix-a-Flat for your home, blowing an aerosol mist of sealant into a building until the particles have found and filled up every last crack.

To keep the air inside healthy, such buildings use small heat exchangers, with fans inside, to continually bring fresh air in from the outside -- all of it filtered -- while warming it with an outflow of stale indoor air.

The result is that while a typical home must breathe through its walls and windows to avoid a buildup of moisture or stale air, a passive home is more like a hazmat suit that only takes in outside air where and when a builder desires.

Good in a blackout

That approach does more than just keep out wildfire smoke or other harmful air pollution. It also means passive homes can maintain their inside temperature for much longer in the event of a power outage.

For Attard, that meant not only could he return to his home even before police barricades had been lifted after the 2021 Marshall Fire -- it was still comfortable despite Colorado temperatures that hover around freezing in December.

And it was easier to keep it warm. That is where another feature typical of passive house buildings proved handy: Attard had decided to power everything in his home with electricity, not gas or oil.

Authorities restored electricity to the neighborhood immediately after the danger passed, but waited to restore the flow of gas, so his was the only home in the neighborhood that could be heated, he says.

Attard's home used a heat pump. These are radically different from the types of baseboard and personal electric heaters that use a heating element like the coils in a toaster.

High-end natural gas furnaces tend to be around 95% efficient, meaning they turn that share of the energy that fuels them into heat. But because heat pumps are simply moving heat from outdoors to indoors, they are able to be more than 100% efficient -- as much as 300%. That is, for every unit of energy put into these systems, they can introduce three units of heat into a home.

If that seems to violate the laws of thermodynamics, keep in mind that there is always heat outside, even on the coldest days. Heat pumps move it from one place to another, rather than generating new heat like a furnace or a baseboard heater.

They are essentially air conditioners that run in reverse -- pushing cold air out and dumping the heat they gather back inside your home -- says Prakash Bedapudi, chief technology officer of Lennox International, the Dallas-based heating and cooling company.

Thanks to a Energy Department-funded challenge kicked off in 2021, several manufacturers now offer heat pumps that are as efficient on the coldest days as they would be on balmier ones. Lennox is manufacturing the first of its version of such pumps, which will go on sale by December, says Bedapudi.

Building structures with all the latest tech and techniques costs more than conventional construction. Creating his company's ultraefficient multifamily dwellings means paying a premium of around 7.5% more for materials and labor, says Fischer, the Minneapolis builder.

He can recoup that cost by charging renters in his buildings a flat rate for utilities and rent together, which is less than in a typical apartment but allows for an extra margin above what he pays the utility company. In addition, solar panels on the roofs of his buildings reduce his exposure to the fluctuating cost of electricity.

Armor for homes

As passive house building techniques are adopted to make homes tougher in the face of catastrophes, a broader category of structures known as "resilient buildings" is taking shape. Insurers already offer discounts for homes that have fire-resistant exteriors, for example.

Other builders, like Onx Homes, a start-up that has already built and sold more than 500 homes across 12 sites in Florida, are using new building tech to make homes faster, cheaper and proofed against disasters.

Onx, which is expanding to Texas, prefabricates its concrete homes in factories, including their foundations, says CEO Ash Bhardwaj. They are elevated 3 feet to 5 feet above ground, their walls can withstand up to 175 mph winds and their steel-truss roofs can withstand a Category 5 hurricane, he says. Because the 18 to 20 elements of each of the company's 2,500-to-3,500 square-foot homes are built in a factory, they can be assembled on site in less than 30 days and sold directly to a consumer.

"When we started, we were addressing for speed," says Bhardwaj. "As we went forward, we realized we were addressing for resilience as well."

Eventually, Bhardwaj believes that the growing crisis over insuring conventional homes will push builders -- and consumers -- toward places to live that can withstand all kinds of extreme weather and other natural disasters.

It is the same bet that every other builder I spoke to for this piece is making -- that construction techniques now at the cutting edge will eventually be the norm, because nature, or governments, require it.

Write to Christopher Mims at christopher.mims@wsj.com

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November 08, 2024 21:00 ET (02:00 GMT)

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