Most students entering the four-story atrium of the Lillis Business Complex at University of Oregon in Eugene probably don't realize that the checkered glass wall that floods the space with daylight also helps to power the building.
The south-facing entryway is clad with one of the largest solar glass curtain walls in the Northwest. More than 2,200 6×8-inch solar arrays are sandwiched between two panes of glass to collect solar energy while also shading the atrium space.
The solar wall is but one of the innovations that helped the Lillis Center earn a 2005 Building Team Silver Award.
"This building stands as a great example of how to integrate energy-efficiency measures with building form and makeup," said one of the judges, John Durbrow, AIA, professor at Illinois Institute of Technology School of Architecture. In January, the $41 million, 196,000-sf building earned a LEED Silver certification from U.S. Green Building Council.
The building integrates three different types of photovoltaic arrays: glass-integrated PVs for the atrium curtain wall and skylights, peel-and-stick thin-film PVs on the penthouse metal roof, and flat-rooftop arrays. The PVs were partly funded with state tax credits and are projected to generate as much as 40,000 kW a year.
The PV systems represent only a fraction of the building's energy-reduction scheme, which beats ASHRAE 90.1 by 44% and state code by 37%.
The Building Team's comprehensive daylighting strategy has virtually eliminated the need for electrical lighting during daytime hours, resulting in a 40% reduction in energy use, according to the design architect SRG Partnership, Portland, Ore. The scheme incorporates a control system that automatically adjusts electric light levels and window shades in the classrooms to maintain a daylight factor of 2. When classrooms are vacated, occupancy sensors close the shades and turn off the lights to reduce heat gain and electrical load. Exterior light shelves reflect up to 30% more daylight into the classrooms.
SRG worked closely with the local mechanical/electrical engineer Balzhiser & Hubbard Engineers to develop a novel natural ventilation plan that allowed the team to downsize the air-conditioning system by about 30%. The scheme combines natural ventilation, thermal mass, and ceiling and transfer fans to increase comfort and set temperature from 78 degrees F to 83 degrees F. Air enters each classroom through intake louvers at the exterior and passes beneath a raised concrete floor, cooling it, before it flows into the room through floor grilles. Ceiling fans circulate the air before it returns through ducts at ceiling level. On days when the outside air temperature is unusually warm, mechanically cooled air is mixed with the natural air underneath the raised concrete floors.
The university expects to save 800,000 kW hours a year, equivalent to $52,000 in utility costs, with a 20-year payback on the green technologies.