What It Takes to Go Net-Zero

Architects share their experiences in net-zero building, from persuading uncertain clients to dealing with extreme weather.

At this point, the technology exists for buildings to produce all the energy they need—and that needs to be the norm. Don’t worry: It’s not as hard as it sounds.

William Maclay, FAIA, has a mission: to make net-zero-energy buildings the new normal. “We have the technology, tools, and knowledge we need to do this right now,” he writes in his book, The New Net Zero: Leading-Edge Design and Construction of Homes and Buildings for a Renewable Energy Future (Chelsea Green Publishing, 2014). “We can do it one home, one building, and one community at a time.”

Among the net-zero projects Maclay’s 12-person Waitsfield, Vt., firm has designed: the firm’s own office, in a renovated carriage barn; a traditional gable-roofed house in Newton, Mass.; and the first net-zero, LEED Platinum secondary school building in the United States. Completed in 2009, the Putney School Field House in Vermont achieves a staggeringly low energy use intensity (EUI) rating of 9 thanks to superinsulated walls and windows, a 36.8-kilowatt solar array, extensive daylighting, and air-source heat pumps for use in the winter. In fact, the building produces more electricity than it uses.

From the start, school officials wanted a sustainable gym, but with a budget of $3 million, net-zero was out of reach. Maclay presented three different proposals at three different performance levels, along with projected operating costs for each one over a 20-year period. In the end, the school opted to raise additional funds—about $2 million—for the net-zero version. The calculation was relatively simple: pay now for a building with virtually no energy costs, or pay more later to heat and cool a typical code-compliant structure.

Net-zero projects still represent a fraction of total new construction, but their numbers are on the rise. According to the Portland, Ore.–based New Buildings Institute (NBI), which has been tracking net-zero buildings since 2000, there were 332 verified or anticipated net-zero buildings in the United States and Canada at the end of 2016. Verified buildings have achieved net-zero energy performance for at least one full year. “We see them in every building type and climate zone, but not in every state,” says Ralph DiNola, NBI’s CEO.

Contemporary OfficeCalifornia leads the way, with 137 verified or anticipated net-zero buildings, according to NBI’s most recent tally. That’s no surprise, since the state has set ambitious targets for all new residential buildings to be net-zero by 2020, and all new commercial buildings by 2030. Oregon, with 16 verified or anticipated net-zero buildings, is next on the list, followed by New York (14), Massachusetts (11), and Florida (11). K–12 schools make up the largest portion of verified or anticipated net-zero buildings, followed by offices, colleges and universities, “other” (including a tennis club and a transit center), and multifamily housing.

“If we want to take climate action and try to solve this in the near term,” DiNola says, “we should be focusing on the building sector. We know we can do this today. There are lots of great examples of buildings that have achieved net-zero energy, and in many cases they’re within the cost range of a conventional building.”

The economics of net-zero is changing quickly, adds Amanda Sturgeon, FAIA, CEO of the International Living Future Institute (ILFI), which administers a certification process for net-zero buildings. (The ILFI recently teamed up with the NBI to streamline the process, now called Zero Energy Certification.) “The investment to go net-zero is now about half of what it was about three or four years ago,” she says. “And it can pay back quickly, generally in less than five years, and in some places, even less.”

One factor: the cost of the technology to achieve net-zero—photovoltaic systems and LED lighting, for example—has plummeted. And it keeps improving. “That’s huge,” says Maclay, who says he’s now able to use air-source heat pumps in Vermont’s cold climate zone, something that was impossible just a few years ago.

“This is not leading-edge technology,” DiNola says. “These buildings assemble a set of what we would call ‘state of the shelf’ technologies and strategies.”

For a building to be certified as net-zero by the ILFI, all of its energy needs over a 12-month period must be supplied by on-site renewable energy. No combustion is allowed. The ILFI does allow an “off-site renewables” exception for buildings that, for example, are located in tight urban areas where solar panels aren’t feasible.

The nonprofit think tank Architecture 2030, which in 2006 issued the 2030 Challenge calling for all new buildings, developments, and major renovations to be carbon-neutral by 2030, recently announced a partnership with the World Bank Group’s International Finance Corp. The goal is to support the international architecture and building community in designing net-zero carbon buildings around the world, which they define as “highly energy efficient building[s] that produce on-site, or procure, enough carbon-free renewable energy to meet building operations energy consumption annually.”

DiNola cautions against getting too hung up on labels like “net-zero,” “carbon neutral,” and others. “There should be an openness to these different approaches,” he says. Maclay agrees: Although he believes strongly in the certification process for net-zero, including the ILFI’s highly rigorous Living Building Challenge, he also acknowledges that even “near” net-zero buildings are far better than conventional structures. “If we’re trying to solve the carbon problem,” he says, “I think we need to get pretty creative about the solutions. I’m not so concerned about the label as actually getting the world to change.”

 

Net-Zero in All Climates

The U.S. Department of Energy has designated eight different climate zones in the U.S., and there are net-zero buildings in all but the coldest one. Hot and humid Florida: check. Frigid Maine: check. Rainy Washington state: check. Sun-baked Arizona: check.

Winter HomeIn Basalt, Colo., which is in North America’s second coldest climate zone, the Rocky Mountain Institute Innovation Center is achieving net-zero without conventional heating or cooling. The two-story office building, designed by ZGF Architects, is superinsulated and relies largely on passive solar strategies for heating in the winter, when outside temperatures can drop into the single digits. In the summer, windows open automatically at night to draw in cool air, which keeps the building comfortable without air conditioning. A rooftop photovoltaic system generates enough electricity to meet the building’s energy needs. The average U.S. office building has an energy use intensity rating of 91. Based on its first year of occupancy, the Innovation Center’s EUI is 15.9.

Meanwhile, in hot and humid Dallas (climate zone 3), Austin- and San Antonio–based Lake|Flato Architects recently completed a net-zero big-box store for TreeHouse, an eco-friendly home-improvement company. The interior of the 25,000-square-foot building is lit almost entirely by natural light, which enters the structure via north-facing clerestory windows. A sawtooth roof design maximizes surface area for a huge photovoltaic system, which produces 164 kilowatts of electricity. A Tesla battery stores energy to power the building at night. The building’s heating and cooling systems, says project architect Lewis McNeel, AIA, are “fairly ordinary,” though 60 percent more efficient than those found in a conventional building. A dramatic roof eave projects over the entrance, creating a kind of front porch and shading the building from the blazing Texas sun. Inside, Big Ass Fans help circulate air, allowing for a broader air-temperature range.

McNeel says a typical big-box store in the same location would have an EUI of about 72. “Our target for TreeHouse is 33,” he says. “We’re still looking at the numbers, but we think we’re pretty close.”

TreeHouse co-founder and CEO Jason Ballard, who commissioned Lake|Flato for the project, told Inc. magazine that he estimated the building would cost 25 percent more than a traditional big-box store. Initially, he said, the developer balked at the company’s plans. “But I said I’d pay for it as long as they let me realize the savings on my electric bill,” he explained. Ballard estimates payback could take seven years or less.

 

Convincing the Client

Many net-zero buildings begin with motivated clients who decide to go deep green and then hire an architect to get the job done. Maybe it’s a university that’s willing to pay a premium for a net-zero library because of its long-term goals for sustainability. Or a retailer that wants to show customers its commitment to the environment.

Increasingly, however, architects are leading the way, convincing clients that net-zero is the way to go. “Firms need to be proactive about it,” says Greg Mella, FAIA, SmithGroupJJR’s director of sustainable design and co-chair of the AIA’s 2030 Commitment Working Group. “Clients have fixed budgets, and you can’t necessarily convince them to increase their budgets to make it happen. But you can at least identify a path to allow them to meet their energy goals, and then look at net-zero strategies as an investment. More often than not, a lot of these things make good economic sense.”

More firms are using net-zero experience as a market differentiator, says Ralph DiNola, CEO of the New Buildings Institute. “If you’re going to pitch net-zero to a potential client,” he says, “it’s easier to do if you’ve done it before, or if your firm’s office is a net-zero building.”

Consider the case of Charlottesville, Va.–based VMDO Architects. When the firm met with officials from Arlington, Va., to discuss a proposal for a new elementary school, net-zero wasn’t a consideration—at least not at first. School officials knew about a VMDO-designed elementary school in nearby Manassas Park that had won several awards for sustainability, including a 2010 AIA Committee on the Environment (COTE) Top Ten Project Award.

Office SpaceVMDO’s Wyck Knox, AIA, recalls: “The client basically said to us, ‘We want one of those, but make it better.’ In response, we said, ‘We think that means net-zero.’” VMDO pitched a “zero-energy-ready” building (that is, without solar panels) for $30.7 million, or a full net-zero version for $1.3 million more, which would still be less than the $36 million budget. Not surprisingly, the school district said yes to the full version.

The 98,000-square-foot Discovery Elementary School, which opened in 2015, is the largest net-zero school in the country and was the first built in the region. The design features 1,706 roof-mounted solar panels, enough to produce nearly 500 kilowatts of electricity; a geothermal well field; extensive daylighting plus 100 percent LED lighting; and insulating concrete form construction for high thermal mass. The district is saving about $100,000 a year in energy costs, Knox says.

VMDO and district officials set an initial EUI goal of 23. “We ended up blowing that away,” Knox says. “It modeled at 21, and it’s been performing at 15. And this year, it’s on track to perform at 13.2, which makes it one of the most energy efficient K–12 buildings in the country.”

 

The Economics of Net-Zero

Quantifying the added cost of going net-zero is difficult, given the number of variables: climate zone, building type, and energy and construction costs. A 2014 study commissioned by the Washington, D.C., Department of the Environment determined that the cost premium for conventional energy-efficiency measures was 1 percent to 12 percent, depending on the building type, versus 5 percent to 19 percent for net-zero strategies.

Net-zero design advocates argue that any cost premium will be offset over time by energy savings. “This is particularly valuable to nonprofits, educational and public institutions, the elderly, and others on a fixed income,” William Maclay writes in The New Net Zero. That can be an especially strong argument in the Northeast and other areas where fuel costs are high.

Consider the case of the Rocky Mountain Institute’s Innovation Center. RMI concluded that the project cost 10 percent more to construct (excluding an additional premium for top-grade finishes) than a LEED Silver building in the same area. The institute projects a four-year payback based on estimated annual savings on energy ($8,100) and maintenance costs ($3,000), and a significant annual increase in employee productivity and satisfaction that will benefit the company’s bottom line ($334,100). To calculate that last figure, RMI looked at hundreds of studies compiled and analyzed by Carnegie Mellon’s Center for Building Performance and Diagnostics and computed a conservative 3 percent annual increase in productivity.

Although the institute doesn’t track revenue for each of its individual offices, the numbers have been growing company-wide since the building was completed. The staff at the Innovation Center, for instance, is eventually expected to grow from 30 to 50 employees. “We want people to look at the building and be inspired by it,” says Cara Carmichael, a manager in the buildings practice at RMI’s Boulder, Colo., office., “and realize that net-zero is totally achievable—and it’s not that much more expensive.”

 

What It’s Like to Live or Work in a Net-Zero Building

Net-zero buildings tend to rely on natural daylighting to help reduce energy use: Conventional lighting accounts for about 11 percent of energy use in residential buildings, and 18 percent in commercial buildings, according to the U.S. Department of Energy. But there’s a side benefit as well: daylighting is known to improve employee health, well-being, and productivity.

At the net-zero, Living Building Challenge–certified Bullitt Center in Seattle, daylight is the primary illumination source for every workstation, on every floor of the six-story office building. Even on cloudy days—something Seattle is quite famous for—backup LED lighting is barely used. Employees have celebrated the building’s ample daylight, which is maximized by floor-to-ceiling, triple-pane windows. Generous 14-foot ceiling heights allow for deeper sunlight penetration.

Similarly, the Rocky Mountain Institute (RMI) Innovation Center relies on extensive daylighting, supplemented by LED desk and overhead lights. Workstations are clustered along south-facing windows for maximum daylight exposure. According to a survey of occupants, a full 100 percent of employees said they are either satisfied or very satisfied with the building’s daylighting and LED illumination, and 37 percent felt the lighting “significantly enhanced” their ability to get their jobs done.

Perhaps the most remarkable thing about the Innovation Center, especially given its location, is that is has no central heating or air conditioning. In the winter, it relies mostly on passive-solar measures for heating, combined with a supertight envelope, including R-50 walls and quad-pane windows. On the very coldest winter days, an in-floor electric resistance radiant heating system helps keep employees comfortable. Employees also have the option of using battery-powered Hyperchairs, which look like conventional office chairs but have built-in heating elements (as well as fans for summer use). In the summer, the building automatically draws in cool air overnight, which keeps the interior comfortable throughout the day.

All of these strategies aimed at achieving net-zero also enhance the employee experience. RMI looked at hundreds of studies compiled and analyzed by Carnegie Mellon University’s Center for Building Performance and Diagnostics that showed a 3.6 percent average gain in productivity for individualized temperature control, a 5.5 percent gain for maximized daylighting, and a 9 percent gain for mixed-mode or all-natural ventilation.

 

Learning Net-Zero

Given the growing interest in net-zero design, it’s no surprise that some architecture firms have already positioned themselves as specialists in the field. For many firms, however, doing net-zero means, essentially, jumping right in. That’s what Archimania did when it proposed a net-zero welcome center on I-55, just south of Memphis, Tenn., where the 25-person firm is based. Archimania had done a number of LEED projects, but tackling a net-zero building required some preparation. “I think we all read a lot,” says principal and founding partner Todd Walker, FAIA. “And we looked at a lot of case studies.”

The $3.2 million welcome center, which opened in July, is on track to become Tennessee’s first net-zero structure. (The state didn’t have enough funds for a full array of solar panels on the roof, so, for now, the building is considered zero–energy ready.)

Archimania also plans to build a net-zero office for its growing firm by retrofitting two 60-year-old buildings in Memphis. And construction has started on a net-zero case study house called Civitas (shown), which principal Barry Alan Yoakum, FAIA—who will own and live in the structure—envisions as a kind of “white paper” for sustainable residential design. The 2,700-square-foot house overlooking the Mississippi River will generate 170 percent more energy than it uses and has a targeted EUI of 9. Yoakum and Walker want to show that net-zero is possible—and affordable—even in hot and humid Memphis. “We’re serious about net-zero,” says Yoakum. “And we want to demonstrate our knowledge to our clients.”

This article was originally published in ARCHITECT October 2017