University High-Rise Gets Individual Controls
September 21, 2009
When officials at the University of Hawaii at Manoa (UH-M), the flagship campus of the University of Hawaii, sought an image change to improve on-campus student housing and the campus community itself, they determined massive upgrades were necessary.
For years, students complained about the on-campus housing conditions, and one of the worst offenders was Frear Hall. Thus, a new version was planned as part of a $132 million dormitory renovation and construction project.
University administrators decided to construct a new 12-story facility that includes 810 beds. The original structure was demolished in 2006 to make room for the new $71 million Frear Hall.
From the outset, offering a/c was a high priority, but being able to monitor individual usage presented a problem, especially because UH-M was aiming for Leadership in Energy and Environmental Design (LEED) silver certification.
A UNIVERSITY FIRSTFrear is the first new dormitory in over 30 years, and it is one of the only ones with a/c. Notkin Hawaii Inc. served as the project’s mechanical engineer, and according to the firm’s Keith M. Chan, P.E., the university sought an a/c system to provide climate comfort with the ability to maintain proper cooling and dehumidification at an economical cost.
The university also wanted the ability to submeter or monitor each fan coil unit’s a/c usage for educational purposes and/or to charge the individual students appropriately. “Having each bedroom’s a/c consumption monitored was required and was a challenge, and the a/c system chosen had the capability to do this,” said Chan.
The project developer, American Campus Communities (ACC), sought an a/c system to provide a central point of control and a remotely accessible control system. This was required to facilitate future system troubleshooting and diagnostics as well as for overall HVAC control, with the goal of increasing operational efficiencies and lowering energy consumption.
Xavier Garcia, vice president of project management for ACC, explained that Notkin and CTG Energetics - the project’s LEED consultant - were collectively tasked with investigating systems compatible with this plan while also adhering to the LEED criteria. Swinerton Builders – Hawaii also teamed with ACC to select the designer consultants and present the winning proposal to the university.
After exhaustive research, the Daikin two-pipe VRV heat pump systems were selected. According to Silas Collier, Swinerton’s senior project manager, what made the Daikin system so well suited for the project was not only its high level of efficiency and control, but also its small footprint.
“To provide the same amount of cooling to over 600 rooms with a conventional system would have required a large amount of ductwork running both horizontally and vertically throughout the building,” said Collier. “In a structure where every square inch was optimized, the routing within walls of small-diameter refrigerant lines greatly simplified construction.”
According to the installers, the low-profile, wall-mounted fan coil unit in each room and compact air-cooled condensing units on the roof were also easy to transport and install.
“Other types of a/c systems were considered, including chilled-water and window units, but the variable refrigerant flow [system] allowed the most flexibility and value for the high-rise dormitory situation,” explained Chan. “Daikin offered the best value, and we had the most confidence in their product.”
INTELLIGENT ENERGY MANAGEMENTAnother integral part of the project’s energy-efficiency equation was Daikin’s Intelligent Manager III, which, like all of Daikin’s multizone control products, offers independent operational aspects. “All space temperature control demand and requirements are managed at the local level between the students’ a/c unit and the outdoor condensing unit supplying it with refrigerant,” said Robert Giba, Daikin project manager. “The Intelligent Manager control system is aware of these demands and requirements; however, it only reacts to enforce other changes or adjustments when specific parameters or boundaries are exceeded.”
The UH-M staff also has access to the Intelligent Manager III system through their intranet and Internet connections as well as detailed e-mail.
This system was an essential part of the Frear Hall project’s energy efficiency. In conjunction with the control system, the owner selected the Power Proportional Distribution (PPD) option, which apportions total outdoor unit power consumption back into the respective indoor units served by those outdoor units. PPD mathematically calculates each indoor unit’s portion of the outdoor unit’s total power consumption based upon its return air temperature, electronic expansion valve position, and baseline values determined by the factory.
Ultimately, UH-M uses this calculated power consumption data to help students understand their individual consumption of the a/c resources, but the main Intelligent Manager III energy management function employed on this project is the temperature set point limitation feature.
“This feature prevents the individual wall-mounted air conditioners from accepting any cooling temperature set point value below 73°F,” said Maritas Calad, vice president of Norman S. Wright. “This feature alone provides enormous energy savings and reduced equipment wear.”
Additional energy management functions include the ability for administration staff to turn off or setback individual dorm room air conditioners from their offices prior to leasing and occupancy. Further, if desired, they can completely restrict operation of those systems until the space becomes leased and occupied. Once it opened in late 2008, the building received LEED silver certification.
For more information, visit www.daikinac.com.
Publication date: 09/21/2009