A Comparative Financial Analysis of Energy-Saving Initiatives: Is Exhaust Stack Energy Reduction Worth Pursuing?
Jeff Reifschneider, CPP, Inc.
Brad Cochran, CPP, Inc.
Traditional methods to reduce energy consumption in laboratory buildings have largely ignored the exhaust system component of the building. The energy savings associated with reducing the exhaust stack velocity/flow, however, can be significant. As a result, optimizing the exhaust systems on new and existing buildings should be a very high priority for designers, engineers, and facility energy managers.
If properly implemented, from an air quality perspective, this strategy can safely reduce the energy consumption of the exhaust system by approximately 50 percent compared to a typical constant air volume system. This can equate to a reduction of up to 15 percent of the laboratory's total energy use.
The first exhaust stack energy reduction initiative using a wind tunnel air quality analysis, as the basis of design, was conducted for the Lethbridge Research Centre in 2005, which has a measured energy savings of more than $90,000 per year. Since then, analyses have been conducted for several academic institutions, federal laboratories, and pharmaceutical companies with similar results.
This poster will reinforce that the energy consumption of the exhaust system of laboratory buildings comprises a large percent of the building's overall energy consumption. In addition, the poster will provide an overview of some of the past exhaust stack energy reduction initiatives. Lastly, this poster will present the results of a detailed financial analysis for multiple exhaust stack energy reduction initiatives conducted over the last seven years. The analysis will include simple payback, return on investment, net present value, and internal rate of return calculations. The results of the analysis will be compared to published information about energy savings related to other initiatives used in laboratories.
Overall, the poster will provide some background on exhaust stack energy reduction, accompanied by an objective comparison of the financial benefits of exhaust stack energy reduction versus other initiatives used to reduce energy in laboratories.
Jeff Reifschneider is a senior engineer who has been with CPP since 2004. Mr. Reifschneider conducts wind-tunnel and numerical modeling studies related to laboratory exhaust design and regulatory applications. Mr. Reifschneider obtained a Masters of Science in environmental science from the University of Kansas College of Engineering and a Bachelor of Science in biology from the University of Nebraska. At CPP, Mr. Reifschneider has consulted for Eli Lilly, Pfizer, Georgia Tech, Princeton University, the Department of Homeland Security, and the Centers for Disease Control and Prevention. He participated in an ASHRAE research study focused on enhancing plume rise by placing exhaust stacks close to each other, known as stack ganging. Mr. Reifschneider is an active member of the Air and Waste Management Association.
Brad Cochran is a registered professional engineer in the state of Colorado and has nearly 20 years of experience conducting wind-tunnel and mathematical modeling studies related to laboratory exhaust design. Mr. Cochran is active in ASHRAE and is currently serving as the lead author of Chapter 9, Exhaust Stack Design, in the upcoming latest edition of the ASHRAE Laboratory Design Guide. He is a voting member of TC9.10 Laboratory Systems. During the past decade, Mr. Cochran has focused on defining new design techniques to minimize the energy requirements for laboratory exhaust stacks. In 2005, Mr. Cochran developed the first laboratory exhaust system that utilized local wind data to minimize exhaust fan horsepower requirements. He has authored and presented several papers on the subject of energy-efficient laboratory exhaust design for ASHRAE, Labs21, R&D Magazine, Lab Manager Magazine, LabWize, the International Facility Management Association, the Air Movement and Control Association, and the Air and Waste Management Association.