RED WING
A MINNESOTA HIGH SCHOOL LOOKS TO TRANE FOR ANSWERS.
WITH TRANE, RED WING HIGH SCHOOL DOESN’T HAVE TO SHATTER BUDGET, OR RUIN ACOUSTICS TO IMPROVE IAQ.
With changing ASHRAE standards, Red Wing High School in Red Wing Minnesota knew they needed to upgrade their HVAC system to improve their IAQ. But the upgrade presented some challenges for this 267,000 square foot school, because the increased energy consumption required to comply with the new standards would have placed an unanticipated burden on the school’s operating budget. This was, by far, their biggest concern — but not their only one. At the school, mechanical equipment is located close to classrooms and even more acoustically critical spaces, such as the school’s media center, band, choir and orchestra hall, along with their theatre spaces. They needed a solution that would make a noticeable improvement in their IAQ, but would have an unnoticeable impact on their operating budget and acoustics. With Trane, they achieved all of these goals and more.
First, Trane installed 200-ton and 400-ton EarthWise CenTraVac™ chillers. These chillers are legendary for their superior performance, but they are also very efficient — consuming only .59 kW per ton and .56 kW per ton respectively. Trane also installed a Trane Tracer chiller plant automation system further optimizing the chiller plant operation. On the airside, Trane Climate Changer air handlers with Trane Traq integrated dampers automatically monitor and adjust ventilation rates to desired levels. With this equipment, Red Wing would be able to easily comply with ASHRAE standards, and with the cost savings the efficient new chiller enables them to keep their budget on track as well. But that only solved 2/3 of the challenge, as acoustics were very important to Red Wing. Fortunately, acoustics are very important to Trane, too.
John Brady of the architectural firm, Armstrong, Torseth, Skold and Rydeen worked closely with acoustical consultant Steve Kvernstoen and Twin Cities Trane to attain the desired NC levels in the school. The design was greatly aided by the Climate Changer’s Q-fan design, which reduces airside noise by 20 decibels in the first two octave bands compared to conventional centrifugal fans. The system also consists of round ductwork which Trane recommends whenever possible. Round ductwork offers a 25-decibel reduction in duct breakout noise in the lower octave bands compared to regular ductwork. Integrating double-walled discharge plenums, the Q-fans and the round ductwork allowed Red Wing to eliminate almost all attenuators and achieve their acoustical goals. The round ductwork also gave Red Wing another nice surprise — it saved them $70,000 compared to the cost of rectangular ductwork. In addition to those savings they also received numerous rebates from the local utility — $67,000 for using variable frequency drives, $23,000 for installing high-efficiency chillers, and $93,000 for using energy recovery units. But aside from these one-time payments, Red Wing has found their new system not only costs less to operate, they’ve reduced demand and energy charges by $120,000 a year. By anyone’s standards, this job was a complete success. By Trane’s standards, however, it was just business as usual.
With their new Trane system Red Wing received $203,000 in rebates from the local utility, but even more impressive is their annual energy savings — $120,000.
One Trane 200-ton EarthWise CenTraVac chiller;
One Trane 400-ton EarthWise CenTraVac chiller;
Trane Tracer chiller automation system
Trane Climate Changer air handlers
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