2013 Technology Award Case Studies 36 ASHRAE Journal Evaporator Condenser The Medical Center Existing Chillers New Chillers facility utility bills were Chiller 1 2 3 1 2 3 Reused entered into ENERGY Tons 650 750 1250 600 1250 1250 STAR Portfolio ManagRefrigerant R-12 R-12 R-123 R-134A R-123 R-123 er. The site energy was 270 kBtu/ft2 in 2009 Evaporator Temperatures 48.5/42 56/48.5 56/42 52/42 51.95/42 56/42 with a source energy of Condenser Temperatures 85/94.2 85/95 85/95 145/155 85/94.3 85/95 594 kBtu/ft2. The ENkW 543 576 813 895 709 813 ERGY STAR rating in kW/ton 0.84 0.77 0.65 1.49* 0.57 0.65 2009 was 24. The site Arrangement Series Series Parallel Parallel Parallel Parallel energy in 2011 was reduced to 186 kBtu/ft2 (2 * kW/ton includes producing 155 heating water in addition to 42 chilled water. 112 402 kJ/m2·yr) with Table 1: Chiller comparison source energy reduced to 518 kBtu/ft2 (5 882 HWR TWR 926 kJ/m2·yr). The EN- HWS HX CHW TWS ERGY STAR rating is Return now at 58. The site enVFD ergy was reduced 31% from 2009 to 2011. VFD VFD The heat pump chiller currently produces all VFD the heating water needed VFD for the facility. The only remaining steam use is LPS TWR Standard for the kitchen equipChiller TWS ment, sterilizers, and humidifiers. The heat VFD pump chiller has reduced Heating Water the gas consumption reConverter quired to heat the buildTWR Standard ing (Figure 1, Page 35). SR Chiller TWS The existing chilled Heat Pump Chiller/Heater water plant was not able CHS Supply to produce cold enough chilled water for a leav- Figure 2: Heat pump chiller piping. ing air-handling unit temperature of 55°F (13°C). As a result, the maintenance staff had to close the outside air intakes to help cool the building. The new chilled water system is now capable of handling the required outside air while maintaining a 55°F (13°C) air-handling unit supply air temperature. Consequently, the outside air dampers have been reopened. In addition, building pressurization is able to be controlled. The hot and cold calls in the entry lobbies and waiting/reception areas have been eliminated from the ability to control the building pressure. The project included the installation of a heat pump chiller to produce both chilled water and heating water (Figure 2). In a hospital environment, redundancy is a vital part of the design requireTight installation in central energy plant. ments. The addition of the heat pump chiller adds redundancy to both the chilled water and heating water system. This chiller that can accommodate extended shutdowns. Air change rates, is also key to improving the hospital’s ENERGY STAR rating. temperature, and humidity are crucial in reducing infection and Another innovation to this project was the use of BIM and the spread of germs in the health-care setting. This project was detailed phasing construction documents to reduce the down- divided into 14 individual phases to reduce the durations of the time of the chilled water and heating water systems. Most shutdowns. Each phase was checked for quality control before projects have unoccupied hours in the evenings and weekends the next phase could be started. ashrae.org July 2013