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Schools seem to go to extremes when it comes to their mechanical systems. For many, the trend has been to ignore them, fix them on the cheap to remain within constrained budgets, and operate them in ways that often provide a disservice to the very budgets they try to conform to. However, lately they have been trending green, as examples to the students and the community.
Colleges and universities, indeed, have long been recognized as being at the forefront of important societal and scientific trends. Recent reports from the U.S. Green Building Council (USGBC) state that of all LEED-certified buildings, nearly 14 percent are on college campuses, and 3,430 higher education projects were registered or certified under the LEED family of rating systems. K-12 schools are increasingly interested.
ELEMENTARY SOLAROf course, opportunities to use less energy via mechanical system improvements exist in most all school facilities, and they tend to take an interest in the opportunities to set a green example in the community.
When Root Elementary in Fayetteville, Ark., decided to replace a handful of aging rooftop units, plant director David Tate saw an opportunity to do the upgrade with equipment designed to use the least energy possible, and with the ability to produce some of its own energy for operation. Yes, it was a solar system. He selected the SunSource® commercial system from Lennox, which integrates a solar-power system into an Energence® rooftop unit. Tate got three 17-SEER units, each designed to accept up to 21 power-generating solar modules.
“In our school and our community, green is extremely popular,” Tate said. “We’re trying some new things - not just using high-efficiency equipment but rain barrels, LEED design principles, and recycling programs - to see what can happen.
“It’s not only for the energy savings,” he said, “but also to educate our school system’s Green Team.”
For Root Elementary, Tate and his maintenance staff had six solar modules installed for one rooftop unit. Designed with a plug-and-play system for a simpler installation, the system was installed in about half a day, with no changes required to the building’s electrical wiring infrastructure.
Tate was impressed. Not only do the modules capture the sun’s energy, but each also uses its own microinverter to convert the DC power harnessed to AC power and send it directly to the rooftop unit. Because the modules aren’t tied together with a high-voltage line, the system is both safer and more reliable (if shade or dirt hampers one solar module, the others are not affected).
By pairing a 17-SEER unit with the SunSource system, the manufacturer said the school can achieve an effective efficiency of 34 SEER. An online communication module monitors the system and displays its real-time status, allowing Tate to see how much energy it’s producing and the environmental benefits it provides.
Tate “was really excited to see the installation of the monitoring system, which will allow him to track the reduction in greenhouse-gas emissions and energy usage the system allows,” said Lennox Industries’ Donna Peoples. “He and his school want to do everything they can to create a better environment for their students.”
CAMPUS LIFEPacific University, Forest Grove, Ore. (west of Portland), is a smaller college with big ideas. Founded in 1849, it is listed annually by U.S. News & World Report as one of America’s Best Colleges, with the student body numbering just under 3,000.
In addition to research and curricula that focus on sustainability, the school offers a permaculture agricultural project, bike rental program, and organic and local food options, green campus master plan - and five LEED-certified buildings. The first to be rated was the library, which received LEED Gold certification. Every building constructed since then has received LEED Gold status. These include Burlingham Hall, the Health Professions Campus, Berglund Hall, and Gilbert Hall.
Gilbert Hall, a 61,520-square-foot student residence, features 26 apartments and suites for 157 students. PAE Consulting Engineers, Portland, provided the mechanical design. Among other goals, they were tasked with designing the building to achieve LEED Gold certification.
PAE considered five HVAC systems. PAE had to account for some demands particular to student housing, such as low floor heights, open spaces, and erratic usage. Considering these and other needs, and bolstered by Pacific’s experience at Burlingham Hall, the designer recommended the VRF system from Mitsubishi Electric Cooling and Heating Solutions.
The low-profile ducted units can respond to the varying cooling and heating demands caused by the erratic usage patterns because they can control the amount of refrigerant flowing from the outdoor compressor to the individual indoor fan coils.
HVAC contractor American Heating Inc. (AHI), installed the system at Gilbert Hall. In fact, project manager Brian Shea was involved with every LEED installation on the campus.
In addition to its energy profile and modular flexibility, Shea appreciated the convenience the system offered him. “It’s a great option for today’s buildings, where there are more and more tight spaces.” He also pointed out that the modular outdoor units are lightweight, have a smaller footprint, and can often be brought to the roof via the service elevator.
Multiple indoor units on a single outdoor condensing unit allowed for block load sizing, explained a Mitsubishi case study, with fewer and more efficient condensing units delivering additional savings. Energy recovery between zones allows for additional energy savings, and the mild climate can take advantage of heat pump efficiency throughout the year without using supplemental electric heat in winter. And because the system is zoned, a dedicated outside air system (DOAS) could be implemented with air-to-air energy recovery and demand-controlled ventilation.
By continuing to monitor its actual performance, Pacific’s design team determined that Gilbert Hall achieved an Energy Use Index (EUI) of 46 kbtu/square feet/year based on actual energy bills, roughly 44 percent less energy than the average among similar buildings in similar climates. Burlingham Hall had virtually the same EUI, 46 kbtu/square feet/year. The team confirmed that this energy performance has tracked nearly identically over the two years the system has been in operation, despite record-breaking low temperatures the last two winters.
For more information, visit www.lennoxcommercial.com or www.mitsubishielectric.com.
Publication date: 08/01/2011