Our design team worked with this client to design a high-efficient heating, ventilation, and air conditioning system for this new two-story, 32,000 SF medical office and clinic. The facility provides diagnostic tests that include echocardiography, arterial and vascular ultrasound, exercise stress testing, cardiac nuclear imaging, tilt table testing, and cardiac event monitoring.
The primary mechanical system is a four-piped water-to-water ground source heat pump (GSHP). Four 15 ton heat pumps supply the building's heating and cooling requirements using the ground as an energy source. Hot water (110°F) and chilled water (44°F) is distributed to fan-coils via a four-pipe system. An underground Loop field, consisting of 68 vertical bore holes 200 ft. deep, was installed for the required heat transfer. When building load conditions require heating in some areas and cooling in others, the heat pumps take excess heat from the zones requiring cooling to satisfy zones requiring heat.
The building also utilizes thermal storage to supplement the cooling load in the summer months. The thermal storage consists of an underground tank that stores ice. The heat pumps generate the chilled water (28°F) during off-peak periods to make ice. During the day, the chilled-water is diverted through the coils in the ice storage tank to help maintain the chilled water temperature. The ice storage helped to reduce the size of the installed heat pump equipment and also moves energy use to the more cost-effective off-peak periods.
The outdoor air requirements are met by the use of an energy recovery ventilator (ERV). The ERV takes the building's exhaust air and preconditions the incoming fresh air via a desiccant wheel. The desiccant wheel transfers both temperature and humidity between the exhaust airstream and the supply airstream. The result is a reduction in ventilation heating and cooling load and operating cost.