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Guidelines for Energy Recovery

Susan Reilly, Enermodal Engineer, Inc. and Otto Van Geet, National Renewable Energy Laboratory


The objective of our presentation is to demonstrate the potential for energy recovery in laboratories. We will discuss various methods of energy recovery, applications for energy recovery, and the energy implications of the methods.


We will present energy simulation results comparing different energy recovery methods and include results from case studies. The energy recovery methods include enthalpy wheels, heat pipes, run-around loops, and specialty applications such as wrap-around loops. We primarily address energy recovery from the exhaust air to pre-condition the incoming fresh air. Simulation results show there are first cost benefits and operating cost benefits with energy recovery, although it is important to consider the increase in fan energy and associated maintenance costs with the recovery methods. Energy recovery can result in the down-sizing of chilled water and hot water systems. In climates with a substantial heating load, or in facilities with high dehumidication loads, energy recovery is the most effective in terms of annual energy savings. Of the energy recovery methods we cover, enthalpy wheels have the greatest potential to reduce energy use. However, the laboratory mechanical system and contamination concerns may limit the use of enthalpy wheels and other systems. We will address design issues such as these, and identify other valuable resources for further investigation into the use of energy recovery.

Labs21 Connection:

Minimize overall environmental impacts; Optimize whole building efficiency on a life-cycle basis.


Susan Reilly received her Bachelor of Science in mechanical engineering from the University of Colorado, and her Master of Science in mechanical engineering from the University of California in Berkeley. Ms. Reilly is a registered Professional Engineer in Colorado and California, and has 18 years of experience in the building energy field.

Susan Reilly, P.E. is currently president of Enermodal Engineering, Inc., an engineering consulting firm located in Denver, Colorado. Ms. Reilly specializes in simulating the energy performance of commercial buildings using the DOE-2.2 software. She provides design assistance to a wide variety of clients, including the Federal Energy Management Program at NREL, the National Park Service, and private design firms throughout the U.S. She has recently completed work on a large research facility for the University of Hawaii Medical School, as well as analysis of a broad range of efficiency strategies for laboratories in Minneapolis, Denver, Seattle and Atlanta.

Otto Van Geet is currently the Senior Mechanical Engineer in the Site Operations group at NREL, where he has worked on the planning, design, construction and operation of facilities for the past 9 years. Prior to joining NREL, he was a Mechanical Engineer for Sandia National Labs in Albuquerque, New Mexico, for 11 years. Mr. Van Geet has been involved in the design, construction, and operation of energy efficient R&D facilities for microelectronics, photovoltaic, thermal, and biological research, as well as office and general use facilities. This has included integrated building design of clean rooms, supply, exhaust, heat recovery and treatment systems, process gas systems, safety systems, drain systems, fire protection systems, central heating and cooling plants, lighting systems, and control systems. Experience also includes passive solar building design, use of design tools, photovoltaic system design, energy audits, and minimizing energy use. He designed and built an off-the-electric-grid PV power passive solar home in Colorado in which he and his family live. Mr. Van Geet is a Registered Professional Engineer, a Certified Energy Manager by the Association of Energy Engineers, and has been designated a Project Management Professional by the Project Management Institute. He received a B.S. degree in Mechanical Engineering from the University of New Mexico and an A.A.S. degree in Air Conditioning Technology from the State University of New York.

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