Passive and active systems at the Aldo Leopold Legacy Center

image from Legacy Center Web site - click for larger view

Fresh air for the main building is drawn in through a network of concrete pipes buried several feet deep to take advantage of ground temperatures that are consistently near 52 degrees Fahrenheit.

The interior of the main building is heated and cooled using both passive and active systems. Active systems require the use of technology and energy to heat and cool. The passive system is part of the building's siting, orientation and design. Extensive use of windows on the south side of the building, with proper overhang to reduce overheating during the summer, combine with the thermal mass of the concrete floors and other building materials to provide heat from fall through spring. At the Center, a hallway on the south side of the building serves as a thermal flux zone to buffer the passive system from the rest of the building.

A ground-source heat pump system takes advantage of relatively constant ground temperatures to provide additional heat and cooling for the building. Fluid is circulated through a 200 foot loop of pipe that is buried vertically near the building. The fluid is then heated or cooled as necessary by a heat pump before being circulated through a radiant floor system in most of the building, and through radiators in the meeting room. Wood stoves and a Rumford fireplace burn locally harvested wood to provide additional heat when and where required. The Rumford fireplace, tall and shallow, is designed to reflect more heat into the space. I had previously seen Rumford fireplaces at the LEED Gold-rated Schlitz Audubon Nature Center in Milwaukee.

The Legacy Center is a net-zero energy consumer, thanks in part to reduced energy demand resulting from the energy efficient building design, use of day lighting and low energy lighting, and energy-efficient heating, ventilating and air conditioning. The Center captures renewable energy on site through a solar water heating system and one of the largest photovoltaic systems (solar electric) in the state of Wisconsin.

The solar water heating system at the Legacy Center utilizes an evacuated tube solar collector on the roof of the main building. The collector is quite unlike the flat-plate hardware that I was accustomed to seeing during my 10 years in the solar energy industry in Southern California during the ‘70s and ‘80s. Copper pipe encased in glass tubes carries a glycol solution to collect available energy; the fluid is circulated using a fractional horsepower pump. The collector was partially covered by snow on the day of the tour; when fully operational, the heat transfer fluid circulates through a heat exchanger in a storage tank to preheat the water going into the electric water heater. The system should provide most of the hot water required by the Center from spring through fall.

A much larger array of 198 photovoltaic (PV) panels fills the south-facing roof of the main building. These panels convert solar energy to direct electrical current. Inverters – streamlined boxes mounted on the wall of the mechanical room - convert the current to AC before it is fed into the utility grid. Graphic displays on the inverters documented the production of electrical energy, even on the overcast day of the tour. This type of system does not require on-site storage batteries which are expensive, have a limited life, utilize space, and create disposal challenges. Instead, net metering is used to account for the energy delivered by the system to the utility. The Legacy Center’s 39,6 KW PV system is designed to deliver 110% of the annual electrical energy required for operation of the Center. Thus far, actual performance of the system has matched design performance.

While the spirit, the words and the example of Aldo Leopold are timeless, I can’t help but wonder what he might think about all this new technology pressed into service in the name of efficiency and sustainability. After all, a cleaned-out chicken coop seemed to suit his purposes quite nicely. Thanks to Jennifer Kobylecky, the very knowledgeable and well-spoken Education Coordinator at the Legacy Center, for a great tour of this significant project and her follow-up help. For more information on the Center's carbon neutral design and water-conserving features visit the online tour of the center, or better yet, make the trip to Baraboo.

LEED Platinum for Aldo Leopold Legacy Center

The Aldo Leopold Legacy Center encompasses 12,000 square feet in three buildings: the main structure, a freestanding classroom and meeting space that is used seasonally and neither heated nor cooled, and a garage/maintenance facility. The Foundation spent $4.9 million, or more than $400 per square foot of space, to construct the Center as a showcase for sustainable building and energy efficient ideas.

The Center sits on a ledge on the upper end of a parcel that was selected, in part, because it is the place where Leopold died in 1948 while fighting a fire. The property is located approximately one mile via scenic byway from Leopold’s farm on the Wisconsin River near the community of Baraboo. The Shack, a chicken coop that Leopold and his family restored as a cabin to house them during their visits, is the only structure on the farm. Leopold purchased the farm with a commitment to restore the health of the land, which had been exhausted by farming methods that were not appropriate for the soil and the times. In the process, Leopold and his family planted more than 90,000 trees on the property.

A small number of Leopold’s pines and cherry and oak trees were harvested in accordance with sustainable forestry practices and milled to provide the beams and lumber used to construct the Legacy Center. Exterior wood on the three buildings was left to weather; after less than a year some boards have already taken on a silver-gray patina or show the effects of rain and the unusually high snow depths of the year.

The mostly-wood interior walls and ceilings combine with concrete floors and counters, SkyBlend particleboard wall panels and custom glass doors to create a rustically comfortable and fragrant place to work and meet. SkyBlend wall panels are fabricated using 100% pre-consumer recycled wood fiber with no added urea formaldehyde. The panels and interior woodwork were finished with Timber Pro UV Crystal Urethane.

The quality of light also contributes to the overall feel of the Center. Windows and light shelves are positioned to maximize the use of daylight and minimize the need for area lighting during working hours. At noon on the day of the tour, the building spaces were well-illuminated without the use of supplemental lighting.

In the thid and final post on the Center, I'll look at the passive solar design and the mechanical systems used in the main building.

Celebrating Aldo Leopold's Legacy

Conservation is our attempt to put human ecology on a permanent footing.
(Aldo Leopold in Land-Use and Democracy – 1942)

The new Aldo Leopold Legacy Center near Baraboo, Wisconsin, is touted as the highest rated LEED building in the country, having achieved 61 of 67 possible points and a Platinum rating. (LEED - Leadership in Environmental and Energy Design - is the built-environment certification system developed by the U.S. Green Building Council. Subsequent posts will explore LEED in greater detail.) I had an opportunity to tour the Legacy Center on the first of March during the celebration of Aldo Leopold Weekend.

Aldo Leopold is best known for authoring A Sand County Almanac, in which he reflects, month by month, on the passage of time. His observations reflect that which is unique to this part of the country. Leopold’s writing blends the notes of a naturalist with prose that is rich in imagery. The Boston Globe characterized the Almanac as a forerunner to Annie Dillard’s description of creek ecology in Pilgrim at Tinker Creek, and Edward Abbey’s observations about the environs of Moab, Utah in Desert Solitaire. Both of these personal favorites can be found on my list of recommended reading.

The Almanac also includes a number of essays on various aspects of conservation. Leopold's essay on the land ethic is credited with formally changing the way we view ourselves within the larger ecological community, and spurring the development of the environmental movement.

In short, a land ethic changes the role of Homo sapiens from conqueror of the land-community to plain member and citizen of it. It implies respect for his fellow-members, and also respect for the community as such.
(Aldo Leopold in A Sand County Almanac, 1949)

Leopold's exemplary life's work should be understood and appreciated by all, as perpetuated by his words and by the work of the Legacy Center. In Part II I'll describe the experience of visiting the Aldo Leopold Legacy Center and touring its many sustainable design features.