The Northland Pines School District in Eagle River, WI, is the proud owner of the first LEED® Certified School in the Badger State. The school district located in the north woods turned to a firm with extensive experience in designing and constructing sustainable schools in cold climates: Hoffman LLC, located in Appleton, WI. Hoffman, in business since 1892, provides fully integrated planning, architectural design, and construction management services using a design-build approach.
The Northland Pines High School Project presented a number of challenges, including a tight design and construction schedule that had to accommodate the long northern Wisconsin winters and a fixed budget set by referendum at a time of rapidly increasing materials costs between ground breaking in the fall of 2004 and completion date for school opening in September 2006. These challenges were amplified by the need to work immediately adjacent to the existing high school building that was deconstructed after school was out in June of 2006. The school district is located in a pristine region with mature forests, hundreds of lakes, and a community legacy of conservation and environmental protection. Consistent with this legacy, the school district was looking for high levels of indoor air quality, site protection, energy conservation, and water conservation.
The Hoffman design-build approach - TPMg Total Project Management: Vision Taken to the Power of Green - provided a single project team from planning through construction and post occupancy monitoring. The design-build approach also provided a single responsible party that worked closely with the Northland Pines School District. These were key elements in delivering a LEED® Gold project on budget and on schedule. LEED® (Leadership in Energy and Environmental Design) is a program of the US Green Building Council. Having a single team was extremely productive in coordinating the various planning, design, and construction management challenges involved in meeting LEED® requirements.
Northland Pines High School, which opened for the start of the 2006-2007 school year, encompasses 250,000 s.f. contained within a brick two-story building that includes an atrium gcommonsh area, an auditorium, and a four-court fieldhouse with a full-size track. Hoffman completed the project for under $29 million, including LEED® certification-related costs and the enhanced commissioning requirement for LEED®. Project cost for all design and construction costs and fees other than the land was $116 per s.f.
Hoffman recommended Fredericksen Engineering of Mequon, WI, to design the school's HVAC system. Hoffman and Fredericksen have worked together on many projects, and experience has taught them how to meet an owner's budget and performance expectations while squeezing out unnecessary costs.
Fredericksen's design for the HVAC system was guided by a need to balance three critical considerations: to manage first costs, to achieve energy savings, and to provide a healthy, comfortable indoor environment. The wet side of the HVAC system consists of a hot water boiler plant and a chilled glycol cooling plant. The boiler plant pumping is configured in a primary-secondary arrangement. The system comprises eight Patterson Kelly Mod-U Fire non-condensing boilers for optimal heat recovery, two Taco FI Series base mounted pumps to serve the secondary loop, and eight Taco 1600 Series inline pumps to serve the primary hot water loop. The secondary pumps are served by variable frequency drives to allow the pump flow to match the building's load.
The chilled glycol plant pumping is also configured in a primary-secondary arrangement. The system is comprised of a 425 ton air-cooled Trane chiller and two base-mounted Taco pumps. The secondary pump is served by a variable frequency drive to allow the pump flow to match the load in the building.
While many facilities have pumps sized for the total connected load, the Taco pumps for the Northland Pines High School were sized to match the anticipated peak load only. This not only reduces installation costs it also results in more efficient pump operation for the life of the building.
Additional installed Taco equipment includes 16 Plus Two Multi-Purpose Valves, four suction diffusers, two CA and one PS expansion tanks, two air separators, and over 100 Taco Accu-Flo balancing valves.
Fredericksen designed the heating system for -25°F, reflecting the harsh winter conditions experienced in Eagle River. The harsh winter, however, does not preclude the need for air conditioning in summertime; the chiller was sized for 88°F summer conditions. Tower Mechanical Services of Oshkosh, WI, provided the HVAC system installation. The HVAC system's design and energy efficiency were instrumental in achieving seven points for energy optimization under the LEED® certification process (Energy & Atmosphere category).
Hoffman's design for the school, developed in close collaboration with the Northland Pines School District, utilized high ceilings and window location for harvesting daylight. The electric lighting system complements the daylighting and uses a low power density design using highly efficient direct/indirect fixtures. The system was designed by Romes Design of Green Bay, WI, and installed by Newton Electric of Wausau, WI. The gray Low-E window glass has a low visual transmittance to control glare and a low Solar Heat Gain Coefficient to manage unwanted heat gains on the east and west windows. Because of the cold winter climate extra insulation - Dow Cavity Mate Ultra - was placed within the school's walls. Over 80 percent of construction waste was either recycled or salvaged. Water conservation measures include use of waterless urinals and low flow lavatories.
Field commissioning was carried out by CDH Energy of Evansville, WI, and executive commissioning by CTG Energetics of Irvine, CA, and funded in part by the Wisconsin Focus on Energy Program. Electricity use data for the first five months of operation indicate the electricity use is within seven percent of the pre-construction model estimates. Electricity is estimated to be two-thirds of the energy bill. Natural Gas use evaluation is currently underway as data for a complete heating season becomes available.
The lessons in a design-build approach to sustainable design are being directly transferred to the students and teachers at the high school. Energy use data are being logged on the Johnson Controls system and provided for instructional purposes through the school's intranet system. The same system tracks the output of a PV (photovoltaic) renewable energy system provided by Sun & Daughters Renewable Energy of Sugar Camp, WI. The PV system is a gift from Eagle River Light and Water, Wisconsin Public Power Inc., and Hoffman LLC. An energy curriculum provided by the University of Wisconsin-Stevens Point KEEP (K-12 Energy Education) Program is being used to understand how energy is used, generated, and managed. The Northland Pines High School is a living laboratory training future generations for a world where sustainable living is imperative.
INFO: Hoffman LLC (www.hoffman.net) & CTG Energetics, Inc. (www.ctg-net.com)