The 12,000sf Aldo Leopold Foundation headquarters includes office and meeting spaces, interpretive exhibit hall, archive, workshop, and three-season hall. The Center was envisioned as a small complex of structures organized around a central courtyard. This design provides flexibility in managing energy use based on program requirements, creates outdoor spaces for work and gathering, and reduces the scale of the buildings on site. Built where Aldo Leopold died fighting a brush fire in 1948, the Center provides a trailhead to the original Leopold Shack for visitors from around the world.
As part of restoration efforts during the 1930’s and 1940’s the Leopold family planted thousands of trees on their worn out Sand County farm. Seventy years later the forest stands on the 1500-acre Leopold Memorial Reserve showed stress from overcrowding, including poor canopy development and extremely low annual growth rate. Research determined that careful thinning could lead to slow but steady improvement in forest health, including increased capacity for forest sequestration of carbon and greater potential for remaining trees to last 150 years.
Improving the health of the forest provided the raw material to build a building. It also gave the Foundation a way to honor the symbolic importance of the Leopold Pines. The quantity and nature of the wood made available from the thinning shaped the building design. Ultimately, the Legacy Center used over 90,000 board feet of site-harvested wood for structural timbers, doors, windows, finish materials, and artisan-crafted furniture.
How much annual solar radiation falls on the site? How much energy can be harvested from the earth? At the earliest stages, the design team developed an energy budget based on total energy available to the site and worked backward to create a building that operated within those constraints. An important energy saving design strategy was the separation of ventilation from heating and cooling systems via an underground earth tube system. With this approach the amount of air delivered to the building is significantly reduced, minimizing fan power and duct size while allowing the building to use 100% fresh air ventilation.
This strategy provided energy savings 2 to 5 times that of a combined system. Geothermal radiant heating, combined with radiant cooling, also contributed to an extremely efficient mechanical system. A 39kWh solar photovoltaic array produces over 61,000kw hours of electricity annually.
The greatest gains often come from uncomplicated ideas. Over half of all building energy savings are realized through low tech/high yield design strategies. The design team worked to create a stable, comfortable building that quietly performs in all seasons with low mechanical assistance and user effort. A long, narrow building allows optimum natural ventilation and daylight. A south facing thermal flux zone provides a buffer to staff areas and allows occupants to manage natural ventilation and solar gain. Building overhangs shield sun in summer and allow passive gain in winter. The roof design maximizes solar photovoltaic production and bounces indirect light into the building interior. An efficient building envelope minimizes thermal transfer.
The Land Ethic goal of building within available site resources led to new uses for small-diameter trees often discarded or pulped as a by-product of typical forest harvest techniques. The design team worked with the US Forest Service Forest Products Laboratory to develop an innovative round wood structural system used throughout the facility. Because of their outstanding strength characteristics round wood trusses and rafters can span greater interior distances without support. Using this approach reduces the processing required to mill conventional square beams and columns.
The Legacy Center is the first small diameter round log demonstration east of the Mississippi, bringing attention to a new technique for increasing value and reducing waste in eastern pine and hardwood forests. A special edition of A Sand County Almanac has been printed on archival-quality paper made from waste pulp generated by Leopold Pines using an experimental chlorine- and sulfur-free pulping process.
In October 2007, the Aldo Leopold Legacy Center achieved LEED® Platinum and became the highest rated building measured under the USGBC rating system (61 of 61 points submitted). The Legacy Center is the first building recognized by LEED® as carbon-neutral in operation. It achieves today the goals set by the Architecture 2030 Challenge and the AIA “Walk the Walk” campaign to make all buildings carbon neutral by 2030. The Center is a ‘zero net energy’ building designed to produce over 110% of annual building energy needs. It uses 70% less energy than a median office building designed to code.
However, this effort was about more than creating a “high performance” building. It was about putting into practice a broader definition of sustainable design. The goal was to demonstrate how human activity, the built environment, and the natural world are intertwined in a larger cycle of energy and life. Perhaps the more lasting achievement of the Legacy Center will be its strict adherence to a holistic design process consistent with Leopold’s understanding of ecological systems, a process that offers the promise of shared benefit for both human inhabitants as well as the land.