Aldo Leopold Legacy Center
Building on Aldo Leopold’s Legacy: The Aldo Leopold Foundation aims to uphold the land ethic in its new headquarters.
Joel krueger, AIA, hates it when people call the Aldo Leopold Legacy Center one of the greenest buildings in the world. To be fair, the project embodies the modern environmental movement’s conception of green: the net-zero-energy, carbon-neutral project earned 61 points, a new record, in the U.S. Green Building Council’s LEED rating system. But compare the Legacy Center to the original “Leopold shack” and there’s no contest, says Krueger, who served as the Legacy Center’s project manager for Kubala Washatko Architects. The shack, located near Baraboo, Wisconsin, began life as a chicken coop. Using found materials, the Leopold family turned it into a rustic getaway and a home base for ecological research and land restoration. Daylit and naturally ventilated, the shack used no electricity or potable water. More important, though, it helped give birth to a new understanding of environmental ethics. In it, Aldo Leopold wrote A Sand County Almanac and developed his so-called land ethic, which holds that “a thing is right when it tends to preserve the integrity, stability, and beauty of the biotic community. It is wrong when it tends otherwise.”
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The goal for the Legacy Center was “to place the land ethic in the 21st century,” says Buddy Huffaker, executive director of the Aldo Leopold Foundation, which occupies the new building. “Aldo set the bar for us.” The $4-million, 12,000-square-foot Legacy Center is located about one mile from the preserved shack, on land where Leopold died fighting a brush fire in 1948. The main building houses offices and meeting rooms, a library, and space to exhibit Leopold’s writings and other artifacts. Smaller buildings hold a workshop and a three-season lecture hall.
The Leopold property offered an unusual opportunity to employ local resources. In the 1930s and 1940s, the Leopolds planted thousands of pine trees in an effort to restore the health of the site’s exhausted farmland. By the turn of the century, the resulting forest had grown crowded, making it vulnerable to drought and disease. The foundation certified 35 acres to Forest Stewardship Council (FSC) standards and then harvested the weaker trees for use in the project.
Many of the trees were initially considered too small to yield structural lumber. By using them “in the round,” however, the project team built trusses strong enough to span 30 feet without support columns. Other trees became flooring, doors, and cabinets. In all, the team used 90,000 board-feet of Leopold wood in the Legacy Center. “Using our own wood would have pleased my father,” says Nina Leopold Bradley, Aldo’s oldest daughter and cofounder of the foundation. “It seems almost like completing a circle to have planted the pines, harvested them, and then used them to further my father’s philosophy.” The use of local resources extended beyond the wood, however: The average pound of materials used in the Legacy Center traveled only 100 miles to reach the project site.
Bringing Leopold’s land ethic to bear on this century’s challenges, including global warming, meant ensuring the project would be carbon neutral, says Huffaker. The first step toward carbon neutrality was to create a net-zero-energy building, and the first step toward net-zero energy was to reduce loads, says Ron Perkins, principal of Supersymmetry USA, the project’s commissioning agent and one of several energy consultants.
The project team began by designing an efficient building envelope. Structural insulated panels make up about 75 percent of the main building’s shell; where windows dominate, the team used an eight-inch stud wall with blown-in cellulose insulation and a 1.5-inch layer of rigid insulation. Operable windows reduce the need for mechanical ventilation, and daylighting reduces the need for electric lighting.
The building also demonstrates an impressive collection of mechanical innovations. Ground-source heat pumps connect to a radiant concrete slab that heats and cools most of the main building. Three wood-burning stoves and one fireplace provide spot heating in cold weather, and ceiling fans expand the comfort range in warm weather. To temper ventilation air, the team used an earth-tube system consisting of 600 linear feet of concrete pipe buried 13 feet below the building. The sandy site provides a superb source and sink for heat, says Perkins; so whether the outside temperature is 20°F or 85°F, ventilation air enters the building at about 55°F.
The project was anticipated to use only 17,000 Btus (5 kWh) of energy per square foot per year, 70 percent less than a comparable project built to code. On-site renewable energy nudges the project into net-zero-energy territory: A 39.6-kW photovoltaic (PV) system is anticipated to produce a 13 percent surplus of electricity each year. Finally, the project expects to burn no more than two cords of site-harvested wood each winter.
The foundation was set on moving beyond net-zero energy to carbon neutrality, however, a challenge that fell to Michael Utzinger, associate professor at the University of Wisconsin Milwaukee’s School of Architecture and Urban Planning. Since the Legacy Center relies on an on-site well and septic system, the project’s electricity load includes the energy used to supply freshwater and treat wastewater. Utzinger also considered the carbon released from burning wood and looked beyond the building envelope to account for solid-waste removal, business travel, and employee commuting. Utzinger then calculated the amount of carbon sequestered in the Legacy Center’s 35 acres of FSC-certified forestland, thanks to renewed growth following the thinning process. To make up for uncertainties, he cut his estimate in half. Combined with the excess photovoltaic power generation, the resulting sequestration was more than enough to offset the project’s remaining carbon emissions. The Legacy Center is the first project to earn a LEED innovation point for carbon neutrality.
Early in the design process, Huffaker saw that some team members were hesitant to employ unfamiliar strategies. In response, the board of directors granted the team explicit permission to fail and the team did make some mistakes. The team had planned to recover heat from the PV inverters, for example, but underestimated the efficiency of the inverters. “They produce almost no heat,” says Perkins. “We ended up wasting a bunch of money on a good idea that kind of went away,” says Krueger.
The meeting wing, which has a wood floor over a crawl space instead of a radiant concrete floor, has been struggling to maintain comfort during cold snaps. Fortunately, a wood-burning stove has picked up the slack. “We’re not sure if the heat pump is not performing up to standards or if it’s undersized,” says Utzinger. “We were downsizing the equipment throughout the building,” he notes, “which means that if you have any flaw in the control logic or in a piece of equipment, it will show up.”
By all accounts, however, the permission to fail enabled a higher level of success. In 1938, Aldo Leopold wrote, “Our tools are better than we are and grow better faster than we do. They suffice to crack the atom, to command the tides. But they do not suffice for the oldest task in human history: to live on a piece of land without spoiling it.” Seventy years later, the project built on his land and with his materials gives hope that we can transcend this paradox. As Nina Leopold Bradley says, “Simplicity and efficiency might be the answer.”
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