June 29, 2022

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Maxed-out townhouse sets the stage for minimal impact on environment

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Plenty of individual architects and custom builders have contributed to innovations in sustainable home building by designing modular homes and residences that generate their own power, but few of what are known as “production” builders have taken that step.

Production builders include local, regional and national home builders that design and build multiple homes at one time rather than a personalized home for one buyer. But to move the needle on sustainability for the future, all types of builders will eventually need to design and build homes with environmental considerations among their top priorities.

“It’s more common for single-family home builders, especially custom builders, on the West Coast to build modular homes than on the East Coast because there are more factories in the West,” says Cindy Wasser, senior manager of green building programs for Home Innovation Research Labs, formerly the National Association of Home Builders Research Lab, in Upper Marlboro, Md.

“On the other hand, production home builders have more consistent teams of contractors who work on their homes, and they could benefit from modular construction.”

Modular-home construction addresses environmental concerns, speeds up construction and may begin to make a dent in the severe shortage of homes in the United States. Freddie Mac estimated that nearly 4 million housing units were needed to meet demand as of the fourth quarter of 2020.

“Modular construction helps reduce the variables in the components of a house, which in turn helps construction teams meet their goals faster,” Wasser says. “Building parts of homes in a factory controls for waste, allows for more recycling and reduces on-site time for laborers.”

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Van Metre Homes, a regional home builder based in Northern Virginia, recently completed its second “POWERhaus” model, a modular constructed townhouse in Chantilly, Va., which the company is using as a prototype for future townhouse development. Its first prototype was a single-family home.

“We’ve had a factory in Winchester, Virginia, since 2008 where we build roof trusses and wall trusses, so we wanted to do more in a factory setting for greater efficiency,” says Mike Sandkuhler, vice president of building operations for Van Metre Homes, based in Ashburn, Va. “Also, most people in the building industry understand that the skilled labor shortage we’re all experiencing isn’t disappearing. Modular construction can help us manage that shortage.”

Sandkuhler says Van Metre intends to incorporate more townhouses in its product mix in the future, which is why the company chose to design a modular townhouse for its second project.

Van Metre Homes brought in Joseph Wheeler, a professor of architecture and co-director of the Center for Design Research at Virginia Tech’s School of Architecture + Design in Blacksburg, Va., as a consultant while he was on a research sabbatical to help redesign a townhouse model as a prefabricated concept.

“The focus was to develop cartridges that could be built in their factory for greater efficiency,” Wheeler says. “Townhouses require a firewall in between each unit, so we needed to do research and development to be able to make that work within the modular factory setting.”

Two-month construction time

A big benefit of this modular construction is that the townhouse was built in two months when most new construction takes much longer.

“The beauty of modular construction is that the site prep and the foundation can be worked on simultaneously with the cartridges being built in the factory,” Sandkuhler says. “It cuts construction time down from four or five months to two months.”

Van Metre and Wheeler are taking the lessons they learned while building this townhouse for their next project, a row of four townhouses in Ashburn. Sandkuhler anticipates those townhouses to be on-site sometime this summer.

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“The factory is less than 45 miles away from where we’re building, so we reduce the amount of fossil fuel and the time needed to transport the cartridges to the building site,” Sandkuhler says.

Transportation and housing account for more than half of all U.S. greenhouse gas emissions, according to a PBS News report in 2019, with 33.6 percent of those emissions coming from housing. Utility usage accounts for 25 percent of the housing emissions.

Reducing the distance from factory to homesite also addresses the issue of truck driver shortages, Wheeler says.

“We also learned that it’s better to do smaller-scale modular pieces instead of huge panels because this way you don’t need massive cranes and huge trucks that can be difficult to maneuver in residential neighborhoods,” Wheeler says. “Smaller components are also more flexible in terms of design, so you’re not stuck in that big-box mentality of earlier modular homes.”

Future-forward Chantilly townhouse

The first POWERhaus townhouse model, listed for sale at $899,990, includes 2,706 square feet of living space with three bedrooms, three bathrooms and a two-car garage. The model includes a variety of special features since it serves as a research project for Van Metre.

In addition to solar panels, Tesla home batteries to store power and an electric vehicle charging station, the home has high-tech features such as a self-cleaning bathroom, a whole home safety monitoring system, smart mirrors, smart lights and touchless faucets.

The “power” part of the name represents the goals for the townhouse, including:

  • Progressive, for innovative building techniques.
  • Optimized, to deliver peak performance for all the systems in the home.
  • Waste conscious, to build processes that minimize waste.
  • Efficient, to maximize energy efficiency and comfort.
  • Renewable, to increase sustainability by using clean energy sources.

“For this house we choose one of our most popular existing floor plans to convert to a modular design,” Sandkuhler says. “If you walk into this house it doesn’t feel like a modular home.”

Van Metre used optimization software in the factory that tracked every piece of material used and where and when it would be needed, says Wheeler, which can reduce costs for future modular-built houses.

“For the next set of townhouses, we can create a cart with all the pieces in it like a Lego set of nesting products,” Wheeler says. “There’s less waste and lower costs when we can build more efficiently and with more precision.”

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Wheeler says they learned quickly that it’s best to leave off the ceiling of the upper two floors when shipping the cartridges to make everything easier to install on-site.

“In the future, small-scale modular homes will offer homeowners and builders the ability to scale over time,” Wheeler says. “If you design a community to be modular from the beginning, you can develop the lots and spaces between homes to accommodate the addition of future modules. So, you could start with a two-bedroom, one-bathroom house for affordability and scale up to a four-bedroom, four-bathroom house.”

Ultra energy-efficient homes

While the next set of modular townhouses from Van Metre will be energy efficient, the Chantilly POWERhaus achieves net positive standards, meaning the house produces more energy than it uses. The combination of solar panels, airtight construction and extra insulation, along with the Tesla Powerwall for storing solar energy, means that there should be enough extra energy to charge an electric car as well as power the house.

“The commitment to designing and building net positive houses is the direction the market is headed, but cutting-edge innovations are usually found in the custom-designed luxury home market,” Wasser says. “Builders and consumers are really waking up to the need for more sustainable energy, lower energy bills and homes that are resilient to energy outages.”

The Home Energy Rating System (HERS), developed by the Residential Energy Services Network (RESNET), a nonprofit established in 1995, measures energy efficiency in homes. The lower the HERS number, the more energy efficient the home is. A HERS score of 100 means a house was built to 2006 energy efficiency standards. A typical resale home has a HERS score of 130. A HERS score of zero means the home generates as much energy as it uses. A net positive home has a negative HERS score.

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“This is an all-electric house and achieves higher levels of energy efficiency not only because of the way it’s constructed but also because of the systems we installed,” Sandkuhler says. “It has induction cooking and a ductless multi-zone mini-split heating and air-conditioning system that is extremely efficient.”

The Mitsubishi Multi-Zone Mini-Split system is compact and allows you to heat or cool one level of the house at a time instead of the whole house, Wheeler says. The townhouse also has motion sensors for controlling lights and a whole-house energy monitoring system with leak detectors that automatically shut off the water if there’s a leak, all of which add to the home’s sustainability.

“You get a slight energy-efficiency benefit in a townhouse compared to a single-family home, particularly the interior units, because of the insulation benefits of the houses being joined together,” Wasser says.

Not the ‘cheapest of cheap housing’

Building cartridges of a home in a factory provides a controlled environment that eliminates weather delays, but the process doesn’t save money yet, Sandkuhler says.

“We’re saving time in the field, but so far the costs have not come down,” Sandkuhler says. “Our first goal with this project was for research and development, and our second was to increase efficiencies to get this as comparable as we can to homes built on-site.”

Building four kitchens at once is efficient, but Sandkuhler says that the level of attention to each detail is the same as with on-site building.

“There’s a different level of precision required when you stack cartridges on top of each other,” he says. “You need to coordinate every detail. For example, we want all our houses to be solar ready in the future, but that means we needed to make changes to the roof trusses so they can handle the added weight.”

Increasing the affordability of homes built with modular construction is another challenge.

“The goal isn’t to build the cheapest of cheap housing,” Wheeler says. “The goal is to deliver an excellent quality product more efficiently. Eliminating waste and exposure to the weather can bring down costs and so can adapting the use of labor in the factory.”

Eventually, Wheeler believes more skilled contractors will do some of their work in the factory.

“If all the components of each house are uniform and precise, then the on-site portion of construction can be done more easily, and you won’t need a supervisor to oversee everything,” Wheeler says.

One misconception many consumers have is that a modular-built home will be more difficult to renovate or remodel in the future, Wasser says.

“Actually, there are big benefits for the consumer of components being built in a factory,” Wasser says. “It’s a more controlled environment for the construction that allows for higher quality components and more consistency. It won’t impact renovations at all. Homeowners will be able to do anything they want with the house just as if it were built on-site.”

Builders can also “future-proof” a modular house if they choose to, such as installing wiring for a battery panel to store solar power.

“Consumers can come into a showroom and make choices just as they do with other types of new construction,” Wheeler says. “The big difference is that they can move into the house within two months instead of two or three times longer than that.”

For Wheeler and Sandkuhler, the investment of time and money into research to build the POWERhaus is all about using technology to build a better house that will provide the same experience for homeowners as any solidly built house constructed with traditional methods.