ASHRAE Journal - March 2011 - 33

technology award case studies
Building at a Glance
Name: Pierre-Boucher Hospital Location: Longueuil, QC, Canada Owner: CSSS Pierre-Boucher Principal Use: Hospital services (340 beds) Includes: emergency, intensive care, operating rooms, laboratories, nuclear medicine, medical imaging, oncology, sterilization, medical pharmacy, patient rooms, food services and external clinics. Gross Square Footage: 500,000 ft2 Substantial Completion/Occupancy: 2006

Pierre-Boucher Hospital reduced annual energy bills by $210,000. Quebec’s extreme winter climate pres- existing spaces, it is important to harents significant challenges when design- monize existing and future installations. ing efficient building systems and tends In the case of the Pierre-Boucher Hosto complicate energy management. To pital, equipment supervision needs were meet these challenges, the design team periodical (1 hour a day). It was prefercreated a model of the building and its able to opt for new equipment that would electromechanical systems using EE4 allow the same operation mode, avoiding and DOE2.1e simulation software to increased labor costs. This was possible accurately analyze the building loads. by using a dual-compressor centrifugal Subsequently, energy simulation models chiller as a heat recovery device, since it were used in accordance with ASHRAE/ requires less supervision than a typical IES Standard 90.1, to demonstrate the screw or scroll chiller. However, keep energy savings and cost in mind that a centrifugal effectiveness of the prochiller can produce hot posed scenarios, which water with the excess helped determine the most heat from a condenser at favorable design option temperatures limited to for the Pierre-Boucher 105°F to 110°F, (41°C to Hospital. EE4 is an analy43°C) while a screw or sis program created by the scroll chiller can usually Canadian government that work with temperatures is powered by DOE2.1e. ranging from 115°F to The second step in140°F. (46°C to 60°C). volved analyzing the The choice of heat rebuilding’s existing heatcovery equipment subing and cooling infrasequently influences the structures, as well as its selection of certain HVAC Enthalpy wheels recover current operation. This components. In this case, latent and sensible heat. step enables the designer HVAC heating loads had to determine, among other things, if cen- to be met with hot water coils selected tralized heating and cooling equipment at a maximum supply temperature of needs to be supervised periodically (1 115°F (46°C). hour a day), intermittently (1 hour every Next on the to-do list was the iden2 hours) or on an uninterrupted mode (24 tification of energy recovery devices hours a day), all depending on the nature that directly reduce heating and cooling and capacity of the equipment being used loads given that they are the most profsimultaneously. When designing within itable. Enthalpy wheels were selected
March 2011

since, with an efficiency rate of 75%, they significantly diminish annual heating, cooling and humidity consumption. In addition, they also considerably trim down heating and cooling demands, allowing designers to downsize equipment capacity. To enhance heat exchange, wheel selections should be made to limit air velocity at 600 fpm (3.05 m/s). To prevent frost from forming on the wheels, glycol preheating coils should be installed. Enthalpy wheels are programmed to work when outdoor temperatures drop below 50˚F (10°C) or rise above 77˚F (25°C). Between 50˚F and 77˚F, (10°C to 25°C) enthalpy wheels are no longer profitable, since they can increase cooling energy to a point that will exceed heating and humidity savings. The subsequent step involved attacking those significant internal cooling loads that, as explained earlier, hospitals experience throughout the year. Heating is still necessary for the outskirt building
ASHRAE Journal 33

ASHRAE Journal - March 2011

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