The big chill for the Big Island

09/01/2009


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Founded in 1907, the University of Hawaii at Manoa (UH-M) is the flagship campus at the University of Hawaii. However, over the past several years, the university's student housing had become out of date and inefficient. School officials wanted to improve on-campus student housing, along with the community itself.

One of the worst performers in terms of building energy usage was Frear Hall; a dormitory where students complained regularly about the housing conditions and lack of occupant comfort. University administrators decided that a new version of the dorm was needed, and a $132 million dormitory renovation and construction project began.

The school decided to construct a new 12-story facility that included 810 beds. Demolished in 2006, the original structure needed to make room for the new $71 million Frear Hall. In Hawaii's climate, air conditioning was a top priority for the new dormitory. The school contracted Notkin Hawaii Inc. , Honolulu, to be the project's mechanical engineer. Notkin Hawaii needed to supply an air conditioning system that would provide climate comfort with the ability to maintain proper cooling and dehumidification. The university also wanted the ability to submeter each fan-coil unit's air conditioning usage for educational purposes, and possibly charge the student's appropriately.

“Having each bedroom's air conditioning consumption monitored was required and was a challenge, and the air conditioning system chosen had the capability to do this,” said Keith Chan, PE, managing principal, Notkin Hawaii Inc.

The project developer, American Campus Communities , Austin, Texas, sought an air conditioning system that would provide a central point of control and be remotely accessible. This was required to facilitate future system troubleshooting and diagnostics as well as for overall HVAC control with the goal of increasing operational efficiencies. The engineering firm and the project developer selected the Daikin two-pipe variable refrigerant volume (VRV) heat pump systems. The Daikin system would provide the same amount of cooling to more than 600 rooms without requiring large amounts of ductworks running horizontally and vertically within the building.

“Other types of air conditioning systems were considered, including chilled water and window units, but the variable refrigerant flow allowed the most flexibility and value for the high-rise dormitory situation,” said Chan.

Paired with Daikin's heat pump systems, Daikin's Intelligent Manager III allowed the building managers to restrict, turn off, or set back individual room air conditioners from their offices. The space temperature control demand and requirements were managed at the local level between the student's air conditioning unit and the outdoor condensing unit supplying it with refrigerant. Facility managers also have access to the system both through the intranet and Internet connections, as well as a detailed e-mail reporting function.

In addition, the building owners selected the Power Proportional Distribution (PPD) option. The PPD option apportions total outdoor unit power consumption back into the respective indoor units served by those outdoor units. The PPD option 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 will use the calculated power consumption data to help students understand their individual consumption of the air conditioning resources. However, the main function of the building energy manager is the temperature setpoint limitation feature. The feature prevents the individual wall-mounted air conditioners from accepting any cooling temperature setpoint below 73 F.

The incorporation of these systems resulted in the building opening to full occupancy in August 2008 and a LEEDsilver certification for the building.


Acknowledgements

Information provided by Daikin.



AT A GLANCE

During the past few years at the University of Hawaii at Manoa, student housing has become inefficient and uncomfortable. The university contracted Notkin Hawaii Inc. to build a new 12-story, 810 bed, $71 million Frear Hall.

Notkin needed to supply an air conditioning system that would provide climate comfort with the ability to maintain proper cooling and dehumidification. Notkin also needed to provide the university with the ability to submeter each fan-coil unit's air conditioning usage.

Project developer, American Campus Communities, chose the Daikin two-pipe VRV heat pump systems. The Daikin system would provide the same amount of cooling to more than 600 rooms without requiring large amounts of ductworks.

Paired with the heat pumps, Daikin's Intelligent Manager III allowed building managers to restrict, turn off, or set back individual room air conditioning systems from a remote location.



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