Consulting-Specifying Engineer - October 2008 - (Page 16)

M/E Roundtable PARTICIPANTS Controlling lab ventilation Maximizing health and safety performance while minimizing energy consumption is extremely challenging for lab environments, so here’s some expert guidance for design and specification to catalyze solutions for your projects. BY MICHAEL G. IVANOVICH, Editor-in-Chief CSE: Lab ventilation systems are known to be energy intensive. What systemsdesign approaches help save energy? Jacob Tsimanis: There are several major contributors to the energy intensity of lab ventilation systems, including one-pass air conditioning/ventilation system (100% outside air); large internal equipment heat gains; and a minimum ventilation rate required to support a safe environment within the laboratory. However, a number of system design approaches can help to save energy for lab ventilation systems. One approach is to use a heat recovery system which allows reduction of the energy penalty from the one-pass air system. Additionally, the use of heat recovery systems allows extraction energy from the exhaust air for the outside air precool and preheat. Another method is to use a variable volume (VAV) system. As the required airflows within the laboratory will vary with the ventilation demand and with fluctuation of the external/ internal loads, the variable volume system is able to address the required fluctuation within the space by increasing or decreasing the flow based on the space demand. The use of VAV systems helps by reducing laboratory airflow from 10 to 12 air changes per hour (ACH) to a minimum of 6 ACH. Use of a chilled beam system as a supplement to the conventional lab air system also produces substantial energy reduction. The combination of these two systems allows merging the minimum of six air change requirements delivered by the conventional lab air system and supplemental cooling/heating requirements delivered with a chilled beam system. The pumping energy of the chilled beam system is by far more efficient than the energy required for the air delivery by a conventional air system. Traci Hanegan: Try starting at the programming phase to minimize the quantity or length of fume hoods or biological safety cabinets. Helping owners understand the cost and energy impacts of their preferences upfront could make them reconsider their needs. For example, a 6-ft-long biological safety cabinet could exhaust 500 cfm or 1200 cfm, depending on whether it is a Type A2 or Type B2. The owners may find that they can modify their work process to enable them to use a Type A2 instead of a Type B2. Or they could perform their Type B2 work in a 4-ft-long cabinet and complete the rest of their work in a separate 4-ft-long Type A2 cabinet, thereby reducing the overall airflow. Better yet, the owners may be able to safely use a recirculating cabinet without any exhaust to the outside. I also suggest minimizing sash openings or revising the sash configuration, which can help save energy. Another approach is to use snorkels or canopy exhausts where safe to do so, rather than a fume hood, to reduce exhaust airflow. Efficiently planned spaces will result in less square footage for a lab. This reduces the volume of air required to meet air change requirements. This strategy is more on the shoulders of the architects and lab consultants. An engineer may suggest that lab and non-lab areas be separated as much as possible so that less area is required to meet lab air change requirements. Also: • Consider heat recovery options such as heat pipes and run-around loops. • Use oversized ductwork, filters, and coils so that the velocities and subsequent pressure drops are reduced, which reduces fan energy. • Provide primary air for makeup to rooms and use recirculating fan coils or radiant cooling panels Joe Brooks Director of Engineering AMCA International Inc. Arlington Heights, Ill. Diane Feliciano-Welpe Director, Life Science Solutions Siemens Building Technologies Inc. Buffalo Grove, Ill. Traci Hanegan, PE, LEED AP Principal Mechanical Engineer Coffman Engineers Spokane, Wash. Ryan Sprangers, PE, LEED AP Mechanical Engineer KJWW Naperville, Ill. Jacob Tsimanis, PE, LEED AP Client Leader and Mechanical Engineer/Associate Partner Syska Hennessy Group Los Angeles 16 Consulting-Specifying Engineer • OCTOBER 2008

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Consulting-Specifying Engineer - October 2008 Contents Viewpoint Letters News M/E Roundtable Cities Under One Roof Eight Design Tips for Integration Is 'Green' Really New? Down the Drain Product of the Year Awards Codes & Standards Case Study New Products Equipment Lifecycles Advertiser Index Green Space

Consulting-Specifying Engineer - October 2008

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