UC Merced Classroom and Office Building Two (COB2)
As the youngest campus in the UC system, UC Merced’s real estate portfolio is a showcase of green building design. The newest addition, completed in 2016, is only the second classroom building to be opened on campus. Known as COB2, the three-story LEED Platinum building houses lecture halls, classrooms and office space, and was designed using traditional passive strategies coupled with numerous advanced building technologies.
The building gains UC Merced’s 17th LEED certification, and its 8th Platinum level building, by merging passive architectural strategies with innovative technology solutions.
View of the northwest and southwest facades.
The building’s architectural form reveals its numerous passive design strategies. Exterior covered walkways facing south and southeast fully shade the first floor lecture halls and second floor classrooms from direct solar radiation, and preclude the need for conditioned circulation spaces. Larger window areas were carefully located where open offices and social gathering spaces can benefit from exterior views and daylight. Vertical fins and horizontal projections have been tailored for each orientation to control glare and heat gain. A line of clerestory windows above a two-story atrium brings daylight into the core of the building. These elements enable daylight harvesting, which is controlled using a multi-zoned low voltage switching, dimming daylight control and occupancy sensors. The building massing also shields the building’s courtyard from prevailing winter winds; this outdoor space is filled with trees and benches to create a flexible place for class changes and student activities.
While passive strategies reduce potential lighting and mechanical loads, advanced HVAC strategies have been tailored for specific occupancies to further reduce energy use. Office areas are conditioned with dedicated economizer-based variable-air-volume (VAV) air handlers. In perimeter private offices, the project team selected ‘Therma-Fuser’ brand VAV diffusers that individually respond to zone temperature and regulate airflow. This allows each private office occupant the flexibility of setting their own space temperatures without influencing adjacent zones, preventing over-conditioning and improving overall occupant comfort. In perimeter areas the VAV diffusers are interlocked with the windows to stop delivery of airflow when windows are opened. Lighting occupancy sensors are linked to the HVAC system to relax temperature and airflow setpoints in areas where no occupants are present.
The southwest facade includes exterior balconies adjacent to public spaces.
In spaces with intermittent and/or high occupancies such as conference rooms and classrooms, demand control ventilation control is utilized to mitigate high CO2 levels. Lecture halls have dedicated air handlers, with underfloor air distribution to deliver air directly into the occupied zones of the rooms and with more moderate supply air temperatures. In these spaces, the individual AHUs also utilize heat recovery wheels and indirect evaporative pre-cooling to temper incoming outside air. Finally, the system is designed to reduce fan power energy and friction losses, with low pressure supply air and low cooling-coil face velocities.
To enable robust HVAC control and energy monitoring, the building was extensively metered with individual meters to lighting panels, mechanical equipment and variable speed drives. Individual BTUH meters for chilled and hot water from the central campus loop further inform energy monitoring and performance.
A central space topped by clerestory windows offers meeting spaces and brings daylight into the core of the building.
Water consumption in the building has been reduced by 43 percent below the baseline through the use of low-flow fixtures. Multiple water meters are in place to monitor water consumption, with meters for the building potable water, reclaimed water, irrigation water and domestic hot water makeup. Drought tolerant plants, removal of all turf, and drip irrigation reduce landscape water use by 50 percent. The irrigation controls use an evapo-transpiration (ET) system from Tucor. The controller predicts water loss from plants through evaporation and transpiration, based on the type of plants and environmental factors. The controller is linked to a weather service that considers the previous day's expected ET rate, and automatically makes adjustments to the irrigation timing. Also, the entire plaza serves as a storm water retention basin for this part of campus, utilizing structured soil to a depth of four feet and pavers with permeable joints that allow water to permeate the surface.
The project team invested significant time to source sustainable materials; overall the building materials include 51 percent recycled content, the highest percentage of any UC Merced building to date. In lecture halls Tectum brand acoustical panels are installed, these are made from a species of tree which grows back from the root structure after being cut, and is considered a rapidly renewable product. The wood is air-dried, reducing its embodied energy, and is not treated with chemicals. Thermafiber brand mineral wool insulation of R-25 in walls has a minimum 70 percent post-industrial recycled content. Carpet tiles by Interface have 36 percent post-industrial and 33 percent post-consumer recycled content. An impressive 93 percent of construction waste was diverted from landfill through a range of creative processes and initiatives.
Finally, the project team used the LEED Campus Guidance system to streamline the certification process. The approach is applicable for projects on a single site and under the control of one entity, and the COB2 project team received 19 LEED points through this process. The use of this approach is especially useful for campuses such as UC Merced where the pursuit of high LEED certifications is standard practice.
Photos by Bruce Damonte.