In 2010, the energy managers at UC Santa Cruz were looking for a way to reduce lighting energy consumption and improve lighting levels in its Science and Engineering Library. As one of two libraries that serve the more than 16,000 students at UC Santa Cruz, this facility houses science and engineering book collections as well as the East Asian Collection, Map Room, and Video Gaming Lab.
University energy managers focused on finding a new lighting solution for this building because existing lighting was fully activated in the morning and remained on until the cleaning staff left almost 20 hours later. Daily occupancy varied and did not follow a reliable pattern.
The university wanted occupancy sensor control and daylight control on perimeter lighting but needed a quick and non-conspicuous solution. Meanwhile, the energy management staff was ready to implement a relamping/delamping project in the library.
In seeking out a new way to control lighting in the UC Santa Cruz Science and Engineering Library, energy managers there began examining offerings from Leviton, a lighting energy management company based in Melville, NY. The company quickly went to work to evaluate the needs of the university for this library facility.
At the time the university was testing a wired photo sensor that involved exposed electrical wiring and was not integrated with an occupancy sensor for the perimeter lighting. Leviton made the university aware of the capabilities of its wireless photo sensor, and from there the two parties began collaborating to identify an effective lighting controls strategy that would reduce energy costs and improve occupant comfort.
They also needed to find a solution that could be implemented relatively quickly, since the university wanted to finalize an installation by the end of 2010 in order to qualify for a utilities incentive.
After careful analysis the Leviton sales team identified the advantages of using wireless technologies over conventional wired technologies, including lower costs for wireless. The company then offered complete device layouts and sample equipment to prove the technology.
A month-long test installation met with positive results and gave way to a full implementation throughout the library. Lighting controls were tested in a quadrant of the library’s book shelving area, and the photosensor product was tested in a perimeter area. The testing confirmed the estimated energy use reduction as well as expected ease of installation.
The System Solution
Upon witnessing the energy use reduction and ease of operation that the proposed system produced, the energy managers at UC Santa Cruz chose to use Leviton’s energy harvesting wireless technologies to achieve their energy goals. LevNet RF receivers paired to wireless occupancy sensors and light sensors also contributed to the energy retrofit of the existing fluorescent fixtures from T12 to T8.
All perimeter lighting fixtures adjacent to windows are now controlled by a wireless light sensor that does not allow the lighting to be activated when there is an abundance of ambient lighting.
Meanwhile, all general use lighting is controlled by LevNet RF wireless occupancy sensors—these sensors force the lighting to the lowest level when the spaces are vacant. The library uses bi-level switching to alternate between levels. This practice equalizes lamp life and drastically reduces energy use. The UC Santa Cruz project involved fluorescent lighting, but LevNet RF controls can also be used any current lighting source, including incandescent, LED, and HID.
Total layout to substantial completion of the project was four months, which meant the university met its target of installing a solution by the end of 2010. Replacing existing T12 linear fluorescent fixtures with a T8 system was part of the utility incentive the university received. An additional incentive was given for the occupancy and light sensors.
By mid-2011, the university confirmed that the library’s actual electricity consumption has been reduced by 50%.
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