Ashrae Journal - December 2008 - (Page 28) Chilled Beams for Labs By Barry M. Barnet, P .E. Using Dual Energy Recovery T his article illustrates the potential energy savings for cooling and heating laboratories by using a design that combines active chilled beams with a ventilation system that uses dual energy recovery. Energy simulations were conducted through an hourly analysis program, using as a model the New Jersey Economic Development Authority (NJEDA) Tech IV building in New Brunswick, N.J. This facility is one in a series of flexible open laboratories conceived to provide state-of-the-art, affordable laboratory, office, and production facilities for emerging and established technology companies. NJEDA Tech IV comprises about 20,000 ft2 (1858 m2) of laboratory, office, and associated support space. According to the U.S. Green Building Council, commercial buildings account for approximately 60% of the electric power and more than 30% of the fossil fuel energy used in the United States. Laboratory buildings typically consume up to 10 times the energy of office buildings.1 The amount of energy needed in laboratory buildings for HVAC typically ranges from 50% to 80% of the total energy used by the building. This HVAC 28 ASHRAE Journal consumption is partially attributable to the high equipment and lighting loads typical for laboratories, resulting in a much greater requirement for cooling energy. However, another key factor is the greater amount of outside air usually required in laboratory applications. The air-handling units for laboratory buildings are typically 100% outside air without recirculation. The amount of outside air required is determined by three basic factors which, ashrae.org on a room-by-room basis, determine the overall size of the 100% outside air-handling unit. The first factor is the minimum required for an acceptable air change rate per hour (ACH). This is generally in the range of 6 to 10 ACH minimum.2 The rooms for which this is the determining factor are described as “air-change driven.” The second factor is the amount of air required to make up for air exhausted outside through hoods and other devices. These rooms are referred to as “exhaust-driven.” The third factor is determined through a traditional design approach, which calculates the amount of air required to cool the room with air supply of about 55°F (13°C). These rooms are called “load-driven.” In a given room, any one of these three considerations can be the determining factor in the amount of supply air required. If a central system is supplying air to various spaces at a constant discharge temperature of 55°F (13°C), the rooms in which the amount of air supply was About the Author Barry M. Barnet, P .E., is senior associate and senior project engineer at HDR CUH2A in Princeton, N.J. December 2008 http://www.ashrae.org
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