Students to Build Ultimate Green Home in Hands-On Design Challenge

House by Northwestern part of 2017 DOE Solar Decathlon

By Roger AndersonApril 17, 2017

The sun will not just power one of Evanston’s newest homes; it will also help to clean it.

Designed with roof-integrated solar panels, ultra-efficient heating and cooling systems, and photocatalytic surfaces that break down harmful pollutants in the air and keep surfaces clean when exposed to sunlight, the student-designed House by Northwestern (HBN) is a showcase of sustainable living.

Construction of the 1,000-square-foot home begins in May near the intersection of Colfax Street and Orrington Avenue in Evanston, but don’t expect to see HBN listed in the local housing market once finished. It’s designed to be a green house on the move.

As Northwestern’s first-ever entry into the eighth US Department of Energy Solar Decathlon — a biennial collegiate competition that challenges student teams to design and build full-size, solar-powered homes — the house will be disassembled and shipped to Denver this fall. There, the Northwestern team will rebuild HBN to compete against a dozen other entries in contests such as architecture, energy production, innovation, market potential, and communications.

“This project is a monumental undertaking,” says Dick Co, faculty director of HBN and cofounder and managing director of Northwestern’s Solar Fuels Institute. “These students aren’t just writing a term paper on how to construct a home, they are actually working with industry partners, Northwestern Facilities Management, and the City of Evanston to design and build one.”

“It will take about three months to build, and once the home is complete and we’ve tested everything from the fire-protection system to light switches, we’ll separate it into three sections and ship it 1,000 miles to Colorado,” says civil engineering major Bill Bach '18, HBN project manager. “This may be a smaller house, but there is a lot packed into the way it functions.”

In fact, the team’s extensive energy modeling studies have shown that HBN will be about 90 percent more energy efficient than its North Shore neighbors. Integral to those efficiencies is passive house design strategies (south-facing windows for example), a dedicated ventilation system, and ultra-airtight insulation. HBN will also rely on a heat pump system that makes heating the home about four times more efficient than the most commonly used Energy Star-rated natural gas furnaces. An energy recovery ventilation system will use energy contained in normally exhausted indoor air to drive a process that will help reduce heating and cooling loads and improve the indoor air quality within the house.

“One of our challenges was to make HBN net positive, meaning it produces more energy than it uses,” says materials science major Joseph Raff '17, who worked extensively on the home’s design. “None of us has ever built a home, so we relied on our own research and advice from our industry partners to make every decision.”

The two-bed, two-bath single-story unit is intended to accommodate a Baby Boomer couple living in Chicago’s northern suburbs. A group of about 10 students has been dedicated to the home’s design since spring of 2016, with more than 30 undergraduates cycling into the project over the past year. During that time, the team also engaged in extensive user research to gain insight on what might be considered a suitable living space for their targeted demographic.

"The user research guided the overall aesthetic of the interiors and helped to optimize user comfort, convenience, and safety throughout the home," says manufacturing and design engineering major Vivien Ng '19. "By scheduling observations and conducting interviews, we were able to collect enough data to identify common user values and integrate them into our final plan."

Sitting at a table inside of Northwestern’s Technological Institute, junior Karla Lopez sketches her latest thoughts. Although the plan for HBN is almost complete, Lopez and Bach say the team is likely to continue tweaking concepts throughout the initial build.

“Pencil and paper is great for brainstorming or when you have an idea that you want to get across quickly,” says Lopez, a civil engineering major. “We then input our thoughts into a digital platform, Revit, where we can do things like explore the home in three dimensions. Bluebeam, another cloud-based application, provides our industry partners an ability to view construction documents and product specs in real time.”

Students relied on their digital toolset to pursue several  in-depth research angles, including:

  • Sunpath studies to explore daylight conditions in the house, and to determine optimum solar panel angles in Chicago and Denver
  • Energy modeling to establish expected heating and cooling loads based on factors such as window orientation and insulating capacity
  • Lifecycle analysis, which helped inform the team’s choice of materials for the four stages of the product’s existence: primary production and processing, transportation, usage, and end-of-life

“It was really important that our design allowed for peak solar gains with photovoltaic panels,” says civil engineering major Gordan Kucan ’17, who led the sunpath studies. “We needed to optimize the slope of the roof where the panels are integrated, while at the same time architecturally fitting them seamlessly into our design, all without exceeding the 18-foot height constraint set by the DOE as part of the competition.”

The team found that by sloping the north side of the roof at 24 degrees and the south side of the roof at 2.2 degrees they could avoid potential shading issues, maintain the architectural integrity of the home, and optimize exposure to the sun. Once final geometric design plans for the home were complete, the team added the roof components in Revit and confirmed that findings from their initial solar studies were correct. Their full energy models were then tested and confirmed using DesignBuilder software with the help of architectural partners from Adrian Smith + Gordon Gill Architecture (AS+GG).

With a project this complex and extensive, financial support from the Office for Research, philanthropists, corporate sponsorships, and in-kind donations are a critical component of HBN. Many partners have generously committed their time and resources to the project, some of which include AS+GG, one of the world’s foremost architecture firms known for its skyscrapers such as the Jeddah Tower; GAF, which is providing all of the roofing material and roof-integrated solar panels for HBN; Schneider Electric, which is providing electrical hardware; electrical subcontractor Kelso-Burnett; The Hill Group, which is installing the home’s fire protection system and plumbing; DIRTT, which creates sustainable, prefab modular interior solutions; and FedEx, which is shipping the home to and from Denver.

As the start of HBN construction nears, Bach and his teammates are developing a schedule to identify key dates for the procurement, delivery, and integration of the home’s many components. It’s more complicated than going to a local hardware store, and the Solar Decathlon will begin October 5 with or without them.

Some of the house’s biggest components are its custom-made structural insulated panels (SIPs). The panels consist of an insulating foam core sandwiched between two boards and will be used for the home’s walls and roof.

“SIPs are great for a number of reasons,” Raff says. “They're a modular solution, so they are designed and built in a location away from the construction site, which makes the final building process much simpler. They are also ecofriendly and have fantastic insulation properties, so the amount of heating or cooling energy that is lost to the outdoors is minimal.”

One of the initial challenges confronting the team when deciding to use SIPs was the realization that they are considered an alternative building material. This meant Bach needed to submit extensive documentation to competition and government officials to prove the panels’ fire safety, strength, and durability.

Many elements in this home, such as bathroom fixtures and kitchen appliances, will be higher-end products, but nothing out of the ordinary, says Bach. “However, we are constructing a house using the cutting edge of sustainable living, which means we need to use both sides of our brain,” he adds. “It’s amazing to think that we’ve done all of this while going to school. I can’t speak highly enough about this experience or about the opportunity to work hand-in-hand with industry leaders before even finishing our degrees.”

Stay current on news and events by signing up for the HBN newsletter on the team’s website or by following them on Twitter and Facebook. For more information on HBN, contact Maggie Waldron at m-waldron@northwestern.edu

Dick Co