ASHRAE Journal - May 2012 - 49

2012 ASHRAE Technology Award Case Studies
The high school project consisted of the renovation and addition to a grade nine to 12 high school in northern Wisconsin (Climate Zone 7) with the goal of improving student services and available programs. The original Northwestern High School was built in 1937 with additions in 1949, 1965 and 1980. The team used integrated design to create systems that provide operational benefits without an increase in construction capital costs. The project involved large two- and three-story additions, with the remainder of the building being remodeled or demolished to accommodate ADA accessibility throughout the facility. The steam heating system was completely demolished and the boiler room was relocated and replaced with two high-efficiency hydronic hot water boilers. One chiller was installed to serve four air-handling units, two for the office areas, one for the computer classrooms, and one for the community and school use fitness area. The building sections allow enhanced performance of the daylighting control and ventilation systems. The selected mechanical systems reduced the amount of ductwork, which enhances the building section design. Exterior materials, such as brick and precast walls, and precast and sloped roofs contribute to the long service life expected for this project. The project was phased and classes were in session from September through May during the project time line from 2007 to 2009. A new boiler room was constructed during the first phase and the building was converted to hydronic hot water heating, along with natural gas-fired semi-instantaneous domestic water heating. The existing boiler room was demolished during Phase Two of construction. Wisconsin Code requires the building to be designed for winter conditions of –25°F (–32°C). and summer design conditions of DB 86°F and WB 70°F (30°C and 21°C). 2009 ASHRAE Handbook— Fundamentals lists the closest Wisconsin location as Hayward, Wis., which is about 50 miles (80 km) south of Maple, Wis. ASHRAE winter design conditions at 99.6% are indicated as –17.2°F
May 2012

A gym that was converted to classrooms was transformed into an auditorium.

(–27°C), and summer design conditions at 1% of DB 84.3°F and WB 69.8°F (29°C and 21°C). Heating degree days (HDD base 65) are 8610 and the cooling degree days (CDD base 65) are 336.

Reuse Before New
Although many of the high school’s component buildings were old, a number of the sections were thought to have value in a renewed facility. The oldest portions were removed. The former small gym that had been converted to classrooms was repurposed again, this time as a sloped floor auditorium. The challenge was to keep it all going while the construction progressed over two years.

allow the use of low-temperature perimeter heating systems. The generous use of precast concrete panels overlaid with a brick cladding also provided a high performance, high mass, low life-cycle cost envelope system.

HVAC Systems
Two 3.3 MMBH (967 MW), 95%+ efficient condensing boilers were designed and installed to handle the entire facility. The hydronic heating system distributes hot water out to the heating system at 140°F (60°C) and returns it to the boilers at 100°F (38°C). The airhandling unit heating coils are designed for a 40°F (22°C) temperature drop. This helps to reduce pump sizing and reduce operational costs by 40% and re-

Energy Efficiency
The basics of energy efficiency start with the site and building orientation. Changes in either of these areas were limited by the existing site, and the desire to improve the outdoor recreational facilities. The gently rolling site was leveraged through location of new entrances and optimizing cut and fill around the complex. Even the location of the rainwater retention and fire protection tanks considered the impact on the amount of fill required (or not required) at the final location under the building. As per standard office practice, the envelope insulation system exceeded code minimum; the spray-applied air barrier, and new high performance windows, created the proper conditions to

Building at a Glance
Maple School District

Northwestern High School

Location: Maple, Wis. Principal Use: Public High School Includes: Classrooms, labs, auditorium, gymnasium, and district offices Gross Square Footage: 175,000 Substantial Completion/Occupancy: 2009 ASHRAE Journal 49

ASHRAE Journal - May 2012

Table of Contents for the Digital Edition of ASHRAE Journal - May 2012