Medical Construction & Design (MCD) is the industry's leading source for news and information and reaches all disciplines involved in the healthcare construction and design process.
Issue link: https://mcdmag.epubxp.com/i/105316
A scout leader friend, also an architect, observed that an initial assessment of site assets is fundamental to good camping. Setting up in a depression, on rocky soil, on the south exposure in summer, promises misery with rain, rest and hot weather. High ground catches the breeze and drains well during a rainstorm. Soft soil absorbs moisture well and is comfortable for sleeping. An east orientation is preferred for afternoon shade; it allows the morning sun to wake the scouts and dry up the dew. These same concepts are easily applied to thermal comfort in healthcare facilities. Thermal characteristics of hospital operation are seldom considered assets in conjunction with system design. In fact, internal heat gain is treated as a nuisance rather than a valuable commodity. The hospital's continuous operation of lights, equipment and human activity always generates heat. Simultaneous high-supply ventilation rates can overcool the space unless the air is tempered. For years the "go-to" solution has been more efficient disposal of internally generated heat with air side economizers, chillers and cooling towers, while neutralizing excess cooling with purchased gas or oil energy. Why should ratepayers spend money to dispose of highquality internally generated energy and then pay again to replace it with a high-extraction effort natural resource? Can the thermal comfort equation for a hospital be balanced without adversely influencing comfort and infection prevention? Yes, the momentum for change has been building for several years. The result has favorable economics when compared to the benchmark dinosaur thermal plant. Mike Hatten of Solarc Engineering and Energy + 52 Medical Construction & Design | January/February 2013 Architectural Consulting, performed energy simulations and developed alternative HVAC concepts for the University of Washington's Integrated Design Lab "Targeting 100" study. System configurations that consistently approached the target Energy Utilization Index 100kbtu/gsf/yr in six U.S. climate regions used earth-coupled thermal sources and distributed heating and cooling systems. Several well-publicized hospital installations of distributed heating and cooling systems use water source heat pumps connected to an evaporative pond or a well field. Closed loop piping exchanges thermal energy with the earth/atmosphere as a thermal battery — extraction in the winter and recharge in the summer. Smith Seckman Reid's Ron Holdaway says, "Lifecycle studies of five systems for a Mississippi project included a high performance chillerboiler-central air system, active chilled beams, variable refrigerant flow and full and partial geothermal heat pump systems. Over an eight-year period, the hybrid geothermal unitary heat pump was the preferred solution after accounting for all architectural, structural, mechanical and electrical construction costs, together with energy, maintenance, repair and replacement." Jim Crabb, principal at PerryCrabb Engineers,logically extends the heat pump chiller and well field combination at two northern Georgia hospitals. Well fields handle base load conditions with closed circuit evaporative coolers for peak heat rejection and annual balance heat pump chillers are essential to an effective heat rejection/recovery strategy. Reject excess heat back into the building reheat requirement rather than into the atmosphere or the well ANDREY CHETVERTAK/DREAMSTIME By James Moler www.mcdmag.com