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GEOMODULE: TURNER CONSTRUCTION; WELLS: GRESHAM, SMITH AND PARTNERS HVAC SELECTION METHODS Identifying the system with the most favorable, balanced response to these criteria required an integrated approach capable of considering multiple parallel factors. To account for each project element, the selection process began with several "all-hands" sessions uniting representatives from different project disciplines to brainstorm feasible HVAC systems and outline advantages and disadvantages. Taking the top fi ve of those systems, the team developed advanced schematic designs that included energy modeling, space utilization analysis, detailed first cost studies and potential operation and maintenance issues, such as equipment replacement or impacts of possible component failures. This process yielded enough data to cross-reference and rank each system, and highlighted some interesting comparison factors: > When the team included the cost of space (both horizontal and vertical) in the first cost comparisons, lifecycle cost was significantly impacted. Systems that used less floor and overhead space proved better first costs and long-term LCC. > Variable refrigerant flow and chilled beam systems showed more energy efficiency than a central all air variable air volume system. A conventional water-source heat pump system was comparative to the VAV system, but with a geothermal option it was dramatically more efficient. Throughout this process, the IPD approach proved extremely valuable. Without the input of all stakeholders, detailed analysis would be impossible and decisions would once again be dependent on generalities and historical industry viewpoints. The selection process needed the construction manager's detailed first-cost estimating, the architect's evaluation of space and equipment impacts, the structural engineer's floor and roof-loading analysis, the owner's assessment of operation and maintenance issues and many other elements. Without this total team effort, Methodist Le Bonheur would have missed a tremendous opportunity to install the system with the best response to project objectives. SELECTING GEOTHERMAL After fully vetting fi ve systems, the team narrowed HVAC choices to two systems: a traditional water-source heat pump system with closed-loop evaporative fluid coolers and gas-fired heat boilers and a ground-source heat pump system with a geothermal bore field. The geothermal system had lower total first costs, when savings in floor space and reduced floor-to-floor heights were included. It improved utility cost performance, and the added investment for the geothermal field was www.mcdmag.com within Methodist's seven-year lifecycle cost analysis. Additionally, its energy profile helped offset increased heat loads from daylighting strategies used to achieve LEED credits. Accordingly, 196 geothermal wells were installed in a bore field near the hospital, supporting 211 geothermal heat pumps throughout MOBH, with dedicated outside air treatment units with heat recovery wheels or plate exchangers providing filtered, dehumidified and thermally neutral air. The geothermal field provides a more efficient heat sink and heat source for the facility, thereby improving energy efficiency, as water is seven times more efficient than air at transferring energy. A water-source heat pump for domestic hot water further enhances the system's energy profile, and final energy models predict an Energy Utilization Index of 122 kBtu/square foot/ year, well below the industry average of 245. Spatially, More than 200 geothermal wells in an onsite bore field support MOBH's 211 geothermal heat pumps. the system eliminates the need for chillers, boilers and air handlers, and dramatically reduces ductwork space, freeing up more room for clinical functions. Each patient room has a geothermal pump, allowing patients to control the room's temperature. Designers created custom soundproof closets to house the pumps, with external doors providing easy maintenance access with minimal patient disruption. MOBH opened to patient care on Aug. 26. Measurement and verifi cation are beginning to monitor the performance of the geothermal system. Because the system selection utilized a multi-disciplinary team approach, and the process included as many considerations as possible, the team is confi dent the right choice was made for the HVAC system. Actual performance of the system will be monitored closely over the fi rst year of operation. Greg A. Gore, AIA, NCARB, is a senior architect in Gresham, Smith and Partners' healthcare market. R. Clay Seckman, P.E., is a senior principal with Smith Seckman Reid, Inc. November/December 2013 | Medical Construction & Design 55