The Aldo Leopold Foundation's ambitious goal of carbon-neutral performance for its Legacy Center started with a net-zero energy target. The project has yet to achieve that distinction, however. Part of the problem is that the PV system isn't providing as much energy as anticipated: a combination of malfunctioning inverters and heavy snows covering the panels has reduced power generation, according to ecological consultant and University of Wisconsin professor Michael Utzinger.
Location Baraboo, Wisconsin (Wisconsin River watershed)
Gross area 11,900 ft2 (1,100 m2)
Cost $4 million
Completed April 2007
Program Offices, meeting rooms, exhibit area
TEAM & SOURCES
Timber frame and trusses Bachmann Construction, made using FSC-certified Leopold-planted wood
Reused timber beams Glenville Timberwrights
Structural instulated panels R-Control
The facility is also using more energy than anticipated, mostly to power extra equipment in the workshop. One of the project's most innovative energy technologies—the earth tubes that temper incoming ventilation air—also carries an unplanned energy load: due to concerns about mold from condensation in the tubes, a 350-watt ultraviolet light is on whenever the building is occupied to treat the incoming air. Utzinger notes that the team had not accounted for that load when comparing the earth tubes to more conventional enthalpy-wheel heat recovery as an air-tempering option.
On the positive side, thanks to the extensive daylighting and energy-conscious occupants who keep the lights turned off, lighting energy use has been running well below predictions. Overall, the facility is purchasing about 15,000 kilowatt-hours annually—roughly 4 kBtus per square foot—to make up the difference. It is also supplementing the ground-source heat pumps in winter with cords of firewood from the property.
The regularly occupied working areas, with radiant heating and cooling, have been quite comfortable, but an unshaded east-facing window in the conference room does cause overheating on hot summer days, Utzinger says. That room is cooled entirely by air, and the air flow isn't enough to overcome that solar load.
The carbon-neutral goal wasn't limited to building energy use. Recognizing that staff who had previously been able to walk to the foundation's offices would now have to drive, executive director Buddy Huffaker insisted that the team include commuting energy use in that calculation. But they also had the forest on their side: Utzinger conservatively estimated that it takes about 20 square feet of managed forest per square foot of building-floor area to absorb the carbon emissions from the net electricity purchases. That leaves plenty of forest to provide firewood in winter and offset commuting, air travel, and other carbon-emitting activities.