Net-Zero-Energy Construction Is Becoming More Cost-Effective

More American real estate developers could be poised to enter the era of the net-zero-energy building, industry experts predicted during ULI’s 2018 Spring Meeting in Detroit.

“A lot of work already has been done with net-zero-energy buildings,” said David Kaneda, a managing principal at the Oakland, California–based Integral Group and an expert on building energy efficiency. “We’ve done over 80 zero-energy buildings, from remodeled office space to residential and including medical, museums, manufacturing, and low-income housing. The results are out there for people to see and learn from.”

Jay Sholl, a senior vice president in the San Francisco office of CBRE and a member of the firm’s Global Corporate Services Group, moderated the discussion, noting that as building codes become more stringent and energy efficiency and renewable technologies become more cost-effective, developers are beginning to aim for net-zero energy in new construction and major renovation projects.

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Kaneda stressed that, unlike the scheduling for other projects, the team for a net-zero-energy building should start working together from day one. “It’s pretty simple to design buildings like this,” he continued. “But the team must work together from the start. Architects sometimes don’t talk to the engineers until later, but with a net-zero-energy building, engineering affects the building design from the very beginning and everyone should be involved.”

According to the U.S. Department of Energy, a net-zero-energy building produces enough renewable energy to meet its own annual energy consumption requirements, thus reducing the use of nonrenewable energy. Net-zero structures use cost-effective measures to reduce energy use through efficiency and include renewable-energy systems that produce enough energy to meet remaining needs. The advantages of net-zero buildings include lower environmental impacts, lower operating and maintenance costs, better resilience to power outages and natural disasters, and improved energy security.

For a net-zero-energy structure, setting an energy-use goal at the onset is critical as is continuing modeling, Kaneda said. He added:

• The choice of building skin is critical to letting heat in or keeping heat out.

• Natural light should be used whenever possible.

• Efficient HVAC systems are critical. “A lot of time, you can use off-the-shelf standard technology in creative ways to get efficiencies,” he added.

• The effect of “plug-in equipment,” such as laptops, copiers, printers, and microwaves, should be determined. “We found that, in a lot of cases, when we measure energy use of buildings, plug-in equipment is more than half the energy,” he said.

Yolanda Cole, senior principal and owner of Hickok Cole Architects, a large commercial architecture and interiors firm in Washington, D.C., noted that a vast majority of net-zero buildings have been completed in sunny California, where the climate is hospitable, and the projects have sufficient space. However, Hickok Cole Architects undertook the net-zero-energy renovation of the American Geophysical Union (AGU) in the historic neighborhood of Dupont Circle in Washington, D.C. “It was a retrofit of a 65,000-square-foot [6,000 sq m] building that was coming to the end of its useful life,” she explains. “The AGU wanted to change the way they worked and become a role model and catalyst for others.”

Working closely with the engineering, contracting, and AGU teams, Hickok Cole decided to use a municipal sewer heat exchange system to recover thermal energy from wastewater. Beneath the street near the building was a large combined storm and sanitary sewer line built in the 1890s. The municipal sewer heat exchange system will tap into the sewer line and divert wastewater to a settling tank outside the building, she told attendees. Water from the settling tank will then be circulated inside the building to an exchange system that will extract energy from the water for heating and cooling before the water is returned to the sanitary sewer system.

In addition, a hydroponic phytoremediation wall system—or hy-phy green wall—will work with the building’s dedicated outdoor air system to reduce energy loads and improve the indoor air quality. Located centrally in the building, it will collect all the return air from each floor for filtering. Most buildings are ventilated with outside air and must be heated in the winter and cooled in the summer, which accounts for more than 30 percent of the energy consumed by a building, she added. The green wall allows indoor air that is already at the correct temperature and humidity to be circulated through the root system of the live plants, where it will be cleaned and filtered of carbon dioxide before passing back into the building.

“We’re doing this for people working in the building,” Cole told attendees. “Our concern was how to make the building work better for them and to make a better building for the planet. The neighborhood loves this building. Net-zero energy matters to people. They can see the importance of the mission and if you do it well, they will be with you in the process.”

Net zero matters to developers, too. Andrew Bush, founder of Boulder, Colorado–based Morgan Creek Ventures, a boutique development firm focused on leading-edge approaches to sustainability, said his firm recently developed a 100,000-square-foot (9,300 sq m) mixed-use net-zero-energy project powered by a full solar roof array and an east-facing, exterior solar wall—the first of its kind in Colorado. “We are a developer and we designed it to make money,” he added. “We care about the design. It’s about occupant comfort and employee health. As a developer, we want a reasonable return on capital. We want great buildings, great daylighting, and employee thermal comfort. We don’t want people in cold or hot offices, and we want places in the building for people to go and get away and still be at the office.”

Bush said his firm has overseen more than 1 million square feet (93,000 sq m) of commercial development across the United States, including one of the first commercial interior spaces in the country rated platinum by the Leadership in Energy and Environmental Design (LEED) rating system devised by the U.S. Green Building Council (USGBC), and one of the first net-zero multi-tenant buildings in Colorado.

“None of it is rocket science,” he added. “We model everything. And we continuously learn. Then we go on to the next project—repeat, refine, and expand. When it works, we repeat it. We redefine details and installation methods. And we develop new integration techniques. Companies get it, but we still need to educate lenders. Lenders like net-zero buildings because lenders believe in lower operating costs. We’re getting there.”