LEED Case Study: Front And Center
By Anne Cosgrove
Published in the October 2012 issue of Today’s Facility Manager
Chartered in 1909 as a private higher education institution, North Carolina Central University (NCCU) in Durham, NC has been educating people for more than 100 years. In 1923, the university became part of the public sphere when the state legislature appropriated funds for the purchase and maintenance of the school. Now part of the University of North Carolina system (which is comprised of 17 schools), NCCU provides instruction in undergraduate and graduate programs, with 77 types of degrees offered.
Set on 135 acres, NCCU’s campus features 60 buildings, and in August 2011 a new residence hall—Chidley North—was added to that inventory. The 134,000 square foot, four story facility was certified LEED Gold in August 2012. It is the second NCCU building to earn this designation from the U.S. Green Building Council. The school’s Nursing Department building was the first, also receiving LEED Silver certification recently.
A Chat With Walter Lennon,
The motivation for building Chidley North revolved around the desire to provide more options for students who were housed off campus. Explains Walter Lennon, project manager in NCCU’s department of design and construction, who oversaw the project, “The university was renting apartments and providing transportation and full-time security for that off campus location. After an evaluation was conducted, it was determined we were spending more than it would cost to provide housing on campus.”
Meanwhile, the Fall 2009 semester marked NCCU’s largest freshman class ever, and the need for student housing was pressing. Currently, university enrollment is 8,349, with about one-third residing on campus.
Bringing more students into campus housing offers other potential benefits as well, notes Lennon. “Research indicates that living on campus improves retention and graduation rates,” he says. “It also promotes social integration and participation in campus activities, which helps increase the probability of graduation.”
At the time, the site was occupied by a residence hall that was no longer suitable for use. Located on the northeast edge of NCCU’s campus, the new facility is one of the first things people see as they approach from that direction. “Chidley North is a beautiful addition to the campus,” says Lennon, “and a welcoming sight in a strategic spot—all the more so because it replaced a facility that was no longer so appealing.”
As part of the LEED pursuit, demolishing the existing structure involved a construction waste management plan. The culmination of efforts resulted in 97.13% of material leaving the site being salvaged or recycled.
In designing the facility, the project team needed to consider several aspects—the students’ needs, environmental issues, and integrating the new facility with an adjacent dorm, Chidley Main Hall. NCCU chose architectural firm Lord, Aeck & Sargent (LAS) to provide architectural services for the project, and Lennon worked closely with the firm to determine how to achieve the multiple goals.
Derek West, an LAS associate who worked as the firm’s project manager for Chidley North, says, “Beyond the essentials of providing a safe, comfortable living and learning environment for students, we were tasked with creating a place that would inspire a sense of loyalty and pride reminiscent of the original Chidley Main Hall.”
Opened in 1951 as a men’s dormitory, Chidley Main Hall is still in use and is a point of pride for NCCU. The design of the new residence hall needed to complement the older facility. This was accomplished by designing Chidley North as a C-shaped structure; its interior exterior façade faces Chidley Main Hall. This arrangement formed a courtyard between the two residence halls, serving to enhance that outdoor area as a place for students to gather.
To determine the layout of the dorm rooms, the project team invited input from NCCU housing staff and students. Says West, “We went through an involved process to present the options for different room types, and the feedback was surprising. Students declared that not sharing a bathroom with a group of other students was preferred over having other amenities, such as a four person suite with a kitchen.”
Accommodating this rooming preference allowed for a more efficient plan than originally considered, with the final bed count totaling 517.
Reflecting on the feedback received after the first year of occupancy, Lennon says, “The students love the hotel style configuration. They also enjoy the amenities that are on each floor; these include a full kitchen, a laundry room, and two study rooms with soft seating and group study tables.”There are 241 double occupancy rooms (each with private bathroom), 11 single units for resident advisors, and six ADA accessible suites, each with two double occupancy rooms and single bathroom.
But there is more to Chidley North than the dorm rooms. The facility also contains a computer lab and a multimedia classroom that all NCCU students can use. The main entrance, located in the building’s center wing, opens into a two level atrium, and the mezzanine overlooking the lobby is where the computer lab and classroom are located.
Many building materials were selected for their low cost of maintenance. The facility core and corridor walls are exposed polished architectural concrete masonry, which were identified as suitable for these high traffic areas. “These surfaces are very easy to maintain,” notes Lennon. “The hallways should never require painting, and the floor material never has to be replaced.”
Commenting on the material choices, West says, “Residence halls are proving grounds for materials durability. They endure a lot of traffic and activity. Ease of maintenance and longevity were priorities for the university, and that is reflected in all material choices, from the stained concrete floors and linoleum on the interior to a zinc roof and brick on the exterior. We designed public spaces and corridors to be finished primarily in exposed, sealed, and stained concrete floors, ground-faced concrete masonry unit walls, steel doors and frames, decorative steel wall panels in the lobby, and native, drought resistant landscaping. All of these materials are holding up well in the building’s second year of occupancy.”
Implementing programs that involve students and cleaning staff were other ways the project team moved toward LEED certification, ultimately earning 40 points. There are recycling stations located on each floor; the building’s housekeeping staff adheres to approved green cleaning methods, and the facility itself is used to educate students and members of the community in green building practices.
Mandate For Sustainability
Earning LEED certification was an internal goal set by NCCU; the initial goal was Certified, and this eventually reached Gold. However, the focus on sustainable strategies (particularly for energy and water use) was spurred by legislation that had been passed by the state in 2007. Lennon explains, “The driving force behind the environmentally friendly design was North Carolina Session Law 2007-546-Senate Bill 668. This requires state university buildings to be built using sustainable, energy efficient methods that save money, reduce negative environment impacts, and improve student performance.”
The legislation addresses both new construction and renovations. Newly constructed facilities should be designed to operate at 30% greater energy efficiency than the baseline set in ASHRAE 90.1-2004 and to use 20% less potable water as calculated for plumbing fixture performance based on the 2006 state energy code.
Three strategies that propelled Chidley North to meet the energy mandate were: an insulated concrete form (ICF) bearing wall assembly, an energy recovery system, and an aluminum sunshade assembly used at the curtain wall sections of the building’s exterior.
Commenting on the decision to use ICF rather than a more traditional concrete masonry exterior wall assembly, West says, “We went with the ICF approach for its insulating capacity, expeditious construction, and its performance in a geographic area where we see great variances in temperature.”
The assembly of the building envelope resulted in a relatively high insulation properties, which would result in reduced energy use for heating and cooling.
Detailing the assembly, West says, “The structure of the building is primarily concrete load-bearing exterior walls and interior concrete masonry unit (CMU) load-bearing walls supporting precast hollow core concrete planks. ICF was chosen as the exterior wall system primarily for its thermal insulating performance characteristics. With 2½” insulation on either side of the concrete bearing walls, the entire assembly—brick veneer, 2″ airspace, 2½” ICF, 8″ concrete, 2½” ICF, and gypsum wallboard—has an R-value of 24. The structurally comparable conventional residence hall assembly would be a CMU structure with 2″ of insulation on the exterior of the structure. All other things being equal, the R-value of that system would be 14, which is 42% less than the chosen system.”
The ICF approach, while more costly than some other construction types, made sense for NCCU when considering long-term costs. Says Lennon, “In comparing options for the exterior wall structure, this was the most economical, based on a 20 year life cycle cost analysis that took into consideration the capital investment and annual electricity cost.”
The building’s energy recovery system pretreats outside ventilation air by recovering the embodied energy in the exhaust air. It reduces the difference between the outside and inside air temperatures and humidity levels by 50%. In addition, a high efficiency chilled water plant in the basement provides cooling at a lower cost.
Explains West, “All of the air from the restroom areas must be exhausted. Additionally, the building has four 100% outside air handling units, each of which has an enthalpy or heat recovery wheel. The HVAC system was designed to pass the exhaust air from the toilet and bathroom areas through the enthalpy wheel, allowing for the heat exchange to pre-temper all the air brought into the air handling units for ventilation.”
He continues, “Using waste energy to precool or preheat the air offsets the differential between outside air temperature and the desired indoor air temperature. This design decision allowed the system to be sized smaller, reducing energy use and long-term costs. The upcharge for the enthalpy wheel and additional ductwork was minimal, yielding a payback of a couple of years. In the long run, it is essentially free energy.”
In order to meet the legislative mandate to reduce potable water use, Chidley North’s design also incorporated a 28,000 gallon underground cistern to collect rainwater from the site, the roof, and area drains. The cistern also collects and reclaims condensate returned from the HVAC system. The collected water is used for site irrigation.
Impact On Operations
To facilitate residents’ comfort, each suite features its own HVAC control system that allows students to adjust the temperature +/-4°F. “Having individual control allows for temperature adjustment to accommodate special situations,” says Lennon. “And the maintenance staff has reported this helps them to identify room temperature problems reported by students.”
With one year of operation complete, Chidley North’s design is delivering in terms of performance, according to Lennon. “The building’s energy costs and consumption are currently exceeding the predicted savings of 33.4% reduced costs and 36.6% reduced consumption. Energy usage is tracked through submeters and energy bills. The university is working on a program to trend and archive the data collected by the direct digital control system on a weekly basis, and examined monthly to verify proper data collection to track steam usage better.”
“We have a building that will be perfectly fine for the next 100 years,” says Lennon. “The ICF walls, roofing system, and overall structure and integrity of the building have resulted in a strong, sturdy facility built for the long term. Chidley North is designed to save energy, and it will pay off over time.”