Building on our Knowledge Base
The Aldo Leopold Foundation embraced new technologies and time-tested ideas to ensure that the Leopold Center would create positive connections between the built landscape and the natural landscape. By looking solely to technological advances to meet the challenges we face, we risk losing a considerable base of knowledge about how to create comfortable, durable buildings with low tech, low energy—but highly intelligent—solutions developed over countless generations prior to the Industrial Revolution. The Leopold Center combines both approaches in a beautiful and functional space.
The Leopold Center’s design influences the workplace and the landscape in positive ways. Offices and meeting spaces are illuminated by sunlight and cooled by natural breezes that carry the sounds of birdsong and rustling leaves. Native plants used in landscaping ultimately blend with surrounding savannas and forests. By maximizing the use of locally-harvested wood, the Leopold Center became an integral part of the ongoing conservation efforts at the Leopold Shack and Farm. Using renewable energy sources to heat, cool, and power the building and cutting our dependence on fossil fuels has positive benefits for people and places around the planet.
Conservation means harmony between men and land. When the land does well for its owner, and the owner does well by his land, when both end up better by reason of their partnership, we have conservation. When one or the other grows poorer, we do not. – Aldo Leopold (1939)
Fitting into the Larger Landscape
The design team thought carefully about the Legacy Center. They considered not only its energy efficient features and green design aspects, but worked meticulously through how the building would fit into the larger context of its local environment, the people who use it, and the landscape of rural Wisconsin: in short, the way the Legacy Center would inhabit its world.
Ecological and cultural values determined placement: the Legacy Center would be close to the Shack without overshadowing it, it would necessarily be above the floodplain, and it would utilize a site already disrupted by human use (an area where two houses had been) rather than disturb a natural area. By keeping the footprint of the improvements to a minimum the remaining site could then be restored to the appropriate ecological communities: prairie, savanna, and wetland.
The team considered the visitor experience, too. How would visitors first approach the building? How would they continue to feel connected to nature once inside? The center employs a campus layout, with many points of access between indoor and outdoor spaces. Native plant gardens around the building, parking lots, and paths further emphasize the beauty of our natural heritage.
The footprint of all impervious areas (building and parking areas) have been kept to an absolute minimum, allowing rain to be absorbed by the vegetation restored on the site. An aqueduct carries the storm water from the roof of the main building to a rain garden, a demonstration of reintegrating rain that does fall on impervious areas slowly back into the ground. A small water feature built into the aqueduct will allow the courtyards to be filled with the subtle and soothing sound of moving water.
The pine trees Aldo Leopold and his family planted in 1935-1948 are a major building component in the Legacy Center. In the form of structural columns, beams, and trusses, as well as interior paneling and finish work, Leopold lumber is featured in all three of the Leopold Center buildings.
Two harvests on the Leopold Memorial Reserve produced approximately 90,000 board feet of lumber for the Leopold Center. Certified by the Forest Stewardship Council through the Community Forestry Resource Center, this material had a market value conservatively estimated at $250,000—more than 70 percent of the value of the total lumber used in construction. Structural materials for columns, beams, and trusses was milled on site, while Samsel’s Ltd., a family-owned sawmill located 70 miles away, milled 65,000 board feet for siding, wall paneling, and other finish material.
Innovative trusses are built from Leopold logs left in the round. These roundwood trusses allowed the architects to design using materials that would usually be considered “substandard” for structural purposes. The logs forming the trusses are of small diameter — between 6” and 8” —that could not be milled into load-bearing square beams. However, by keeping the logs in the round, the sapwood, the strongest part of the wood, is retained, and in the truss formation these logs are incredibly strong. In fact, they are strong enough that they can span the roof of a 30’ deep building without any internal support columns.
When the Leopold lumber could not provide material for square roof rafters, this element of the main building was re-designed to incorporate roundwood rafters. If the rafters had been purchased, they would have been Douglas fir trucked from the West Coast. The smaller diameter logs were on site, locally harvested, and planted by Leopold.
Other locally harvested wood has been used extensively for exterior siding, flooring, furniture, and interior paneling. The remaining building materials, where possible, are comprised of recycled aluminum, reused wood, reclaimed stone, and rapidly renewable materials.
Strengthening our ‘Shell’
To reduce leakage to the outdoors, significant investments have been made in the building envelope. Some of these investments have been relatively standard upgrades to insulation of higher R-values (the measure of a material’s resistance to heat flow), while other investments have been more innovative.
Using structural insulated panels (SIPs) in place of frame construction has been particularly important in increasing the overall R-value of walls. SIPs are composed of a thick layer of Styrofoam sandwiched in between two sheets of fiber board. They often have have locking mechanisms to connect the panels to each other very tightly, decreasing air infiltration. They also provide a continuous insulation layer in the wall, unlike in framed walls where each stud causes a gap in insulation.
Windows were selected for their insulating properties and lower solar heat gain coefficients. As a result, the R-values for almost every part of the building envelope are at least twice the values required by state code.
Beyond using local raw materials, the design team was able to reuse stone from a previous structure in the Leopold Center as well. The beautiful stormwater aqueduct and foyer fireplace are faced with reused Dane County Limestone, a very soft limestone with some of the properties of sandstone. The stone was reclaimed from an airplane hanger built by the Civilian Conservation Corps in the 1930’s at the Dane County Regional Airport. This hanger was torn down to expand the airport. Monona Masonry reclaimed the stone and was able to use it in the Leopold Center fireplace.Carbon Budget
The First Carbon Neutral Building
As the first building to be recognized by LEED as carbon neutral, the Leopold Center has helped to set the standard for carbon neutrality in green buildings for the future. The initial carbon balance for the Leopold Center is based on estimates of carbon flows: emissions from combustion, electricity generation and other foundation activities; projected offsets from renewable energies; and carbon sequestered by the foundation’s forested lands. Accounting procedures and measurement systems have been set in place to record actual carbon flows annually. Estimating conservatively, carbon flows are projected to be:
* Total emissions: 13.42 tonC/yr
Energy modelers have chosen to use figures that should overestimate the Leopold Center’s carbon emissions and underestimate the amount of carbon offset or sequestered, meaning the Leopold Center’s projected carbon budget leaves a cushion for error. By operating within this carbon budget, the Leopold Center now meets the ambitious goals established by the 2030ºChallenge.
Zero Net Energy
To make the Leopold Center carbon neutral in its operation, it first needed to be built as a net zero energy building. The design team studied nine existing high performance buildings to develop performance standards for the Leopold Center. Net building energy demand is calculated as the difference between building energy use and solar energy produced; in a zero energy building, this number should be zero or less. The buildings reviewed are listed by net energy use from least to greatest. Based on the low energy demand of the Woods Hole Research Center, the design team set 5 kWh per square foot floor per year (17 kBtu per SF per yr) as an energy performance goal for the Leopold Center. Given that goal, roughly 3,000 square feet of photovoltaic panels would be needed to produce the energy the building would require, leading to a zero energy building.
Given the extremely low demand of the Woods Hole Research Center, the design team focused on design options that would reduce demand. Four guiding principles for the design team were:
* Design all occupied space as perimeter zones allowing daylight and natural ventilation
Carbon Neutral Analysis
The carbon neutral analysis for the Leopold Center took into account direct and indirect emissions, offsets, and sequestration occurring on the foundation’s forestlands.
Direct emissions of carbon include two sources: stationary combustion devices and fuel combusted in organization owned vehicles. Emissions from foundation vehicles are easy to track by monitoring fuel purchases; tracking emissions for stationary combustion devices requires a little more creativity. The Leopold Center has three wood burning stoves and one fireplace installed in the building. To estimate emissions, the Aldo Leopold Foundation staff will set aside two full cords of wood (approximately 5 tons), to be weighed when stacked) for the 2007 – 2008 heating season. Any wood remaining at the end of the heating season will be weighed again to determine the mass of wood combusted.
Indirect Carbon Emissions due to Electricity Generation
The Leopold Center is projected to generate 61,268 kilowatt hours (kWh) of electricity per year from the solar panel array. At night and on days when solar-generated electricity does not meet the building demand, electricity will be purchased from Adams-Columbia Electric Cooperative
To offset the emissions of the purchased electricity, the Aldo Leopold Foundation has contracted to purchase wind-generated electricity from the utility.
Indirect Carbon Emissions due to Other Organizational Activities
The foundation's long-term goal is to account for all possible carbon emissions due to organizational activities. Emissions due to employee commuting, employee business travel, water supply, sanitation, and solid waste removal are estimated as a part of this carbon balance. Emissions due to visitors traveling to the center will be included once an average visitation rate can be established. Practices such as employee carpooling have not been included in this analysis, but would further lower emissions.
Employee air travel was calculated at a rate of 10.0 lbs carbon per 100 passenger miles. With an estimate of 36,000 air travel miles per year, the annual carbon emissions for business air travel is projected to be 1.80 Tons carbon per year. The Aldo Leopold Foundation will track actual employee business travel (air and car) for a more accurate annual emissions report.
The Leopold Center pumps water from a well on site and uses an on-site septic field for sanitary waste removal. All energy used in the pumps, and, therefore, all carbon emissions due to water and sanitary systems is included in the electric energy consumption of the building.
Carbon emissions from solid waste removal have been derived by estimating the emissions generated per unit mass of material removed. Foundation employees and visitors are asked to recycle as a standard practice; however, recyclables must still be hauled away from the site, contributing to total carbon emissions. The Aldo Leopold Foundation is assumed to generate 5,200 lb waste material per year (100 lb per week) contributing 0.92 Ton of carbon emissions per year.
The Aldo Leopold Foundation owns over 500 acres of forest. Prior to constructing the Leopold Center, the foundation certified 35 acres, including roughly twenty containing red and white pine planted by Aldo Leopold and his family, according to Forest Stewardship Council (FSC) rules. A selective harvest of these acres culled the smaller diameter trees to use as building materials in the Leopold Center. While mature trees have a slower rate of sequestration than rapidly growing saplings, they still are able to store more carbon each year due to their size. Prior to harvest, a percentage of the trees to remain were measured to set a baseline of the volume of wood in the forest. In the fall of 2007, those trees will be re-measured to determine their growth rate and estimate the growth rate of the forest; this measurement will be repeated every 6 years. For now, in absence of a measured sequestration rate, a conservative rate of 500 Lb carbon per acre will be assumed (a conservative estimate). The 35 acres of FSC-certified forest will then be stoing 8.75 tons of carbon per year. The rest of the foundation’s forested acres will not be included in the carbon neutral analysis of the Leopold Center.