LEED Gold rating
Location: Baraboo, WI
Project Manager : Gregg Tucek (Boldt Construction’s central operations)
Products Used: 600 ft. of Concrete Reinforced Pipe
custom air intake manholes, 90-degree bends and T-beams
DNR building earns Gold from LEED ratings
- Aldo Leopold would be proud.
The name of the late environmentalist, often dubbed the father of American conservation, now graces the exterior of the Aldo Leopold Legacy Center in Baraboo, Wis., which finds itself at the forefront of utilizing concrete as part of environmentally friendly design.
The center’s LEED Platinum certification from the U.S. Green Building Council (USGBC) makes it one of the most ecologically friendly structures in America. The LEED (Leadership in Energy and Environmental Design) Green Building Rating is a voluntary standards and certification program from the USGBC which recognizes the world’s greenest, most energy efficient, high performance construction projects. (Read more about the project in the article "Concrete Pipe Used as Earth Tubes for Climate Control System," as featured in the March 2009 issue of The Concrete Producer, a publication of Hanley Wood Business Media.)
While 77 projects have attained Platinum status nationwide, just two are in Wisconsin. The Center received 61 out of a possible 69 points, the highest point total yet recorded by the LEED rating system.
Looking to design influences from Europe, and utilizing some of the most innovative materials and systems ever employed in U.S. commercial construction, the project was built to the highest standards of energy efficiency and sustainability. Project partners include the Oscar J. Boldt Construction Company, one of the leading “green” construction firms in the United States, and Kubala Washatko Architects, Inc. of Cedarburg, Wisconsin, who provided planning, architectural design, and strategic sustainability consulting.
As one of the first cutting-edge “green” systems to be installed in North America, the project team designed the center’s geothermal system and heat exchangers that feed radiant floor heat as well as supply cooling in the hottest summer months. An integral part of the HVAC system for ventilation, the concrete “earth tubes”
were installed early in the construction process, covering more than 5,000 square feet,
with one third of it under the building itself.
County Materials manufactured 600 linear feet of reinforced concrete pipe that naturally warms and cools fresh air pumped into the 12,000-square-foot office-and meeting facility. County Materials also supplied custom air intake manholes, 90-degree bends and T-beams for the project.
The underground conduits comprise a series of connected 24-inch diameter concrete pipe buried more than 10-12 feet deep. Surrounded by earth, the tubes moderate and maintain a steady air temperature of approximately 55 degrees year-round, which ultimately reduces heating and cooling costs.
The maze of pipes enters the structure through the concrete foundation wall and is grouted in place with non-shrink, non-metallic grout.
Said Gregg Tucek, Project Manager for Boldt Construction’s central operations, “The pipe are transitioned into the supply air ductwork via a sheet metal fitting. The air then filters through a UV lamp to eliminate mold and bacteria before being heated or cooled and circulated throughout the building.”
At the other end, Tucek explains, the pipes are connected to a larger vertical air intake pipe extending above the ground. The opening is covered by a metal roof system, and the sides include screening against birds, insects and debris.
The pipe-to-pipe joints are sealed with rubber gaskets, effectively keeping water out and preventing gases in the soil from leaching into the ventilation system. The pipe itself it permeable enough to allow evaporation of any water that may condense on the inside.
According to Joel Krueger, Green Building Specialist and Project Architect with The Kubala Washatko Architects, reinforced concrete pipe was selected because of its thermal properties, ease of installation and economy. Said Krueger, “ In our case, 24” diameter pipe was great and was a readily available pipe size.”
Krueger explained, “The geothermal system requires just the right site, slope and soil type. It is a disruptive install and works best as an air displacement type of air system.”
The center’s sandy site has provided a superb source and sink for heat. Working with the pipe’s available surface area, the airflow rate and the difference in temperature between the air and the ground, calculations determined the change in air temperature entering the building.
“Because the system relies on moving thermal energy either from the air into the ground, or from the ground into the air, we used a thermal transfer rate test on the system to understand how fast the thermal energy would move through the ground,” said Krueger. “Since the ground has an average ambient temperature of around 50 degrees, the thermal energy was roughly interpolated to help us establish appropriate spacing of the pipe in the grid network.”
The building’s heating, cooling and ventilation systems are powered by solar panels, a renewable source of energy rather than natural gas or other fossil fuels. More than 500 sensors monitor energy use, temperature, and even carbon dioxide levels in the building to track the Legacy Center’s performance and indoor comfort levels.
Since opening in the fall of 2007, the building has saved enough in energy costs that the Aldo Leopold Foundation has earned $650 by selling energy back to the local utility. With an annual energy demand matched by the output of clean, renewable energy systems on site, the Center is the first “net zero energy” building in Wisconsin and the first carbon neutral building certified by LEED.
With rising energy costs, the long-term payback is “a bit of a moving target” according to Krueger. However, he notes that they are “in the process of building ‘tweeking’ and data collection.” The project team is currently working with graduate students to increase their understanding of the building’s performance and its carbon impact.
Said Krueger, “ With the concrete air tubes and other consumer reducing systems in place, and the photo voltaic system producing energy, we can continue to be energy neutral or even positive.”
For more information, visit www.aldoleopold.org.