ASHRAE Journal - February 2009 - 40

ASHRAE 19 50 59–2009 YE A R S JOURNAL Air Handling Unit Design for Energy Conservation By ARtHUR E. WHEELER, p.E., fELLOW ASHRAE fEAtUREd iN ASHRAE JOURNAL, JUNE 1977 and design fees. Operating costs include energy and filter replacement. Operating and maintenance labor is excluded on the hypothesis that actual owner payroll expense is unlikely to be affected by the variables introduced with different face velocities. Property taxes and insurance have also been excluded as having negligible impact upon the study. Several methods of economic evaluation are applicable. Annual cost comparison of alternatives–amortizing first cost over the equipment life or a preselected payback period and adding operation cost to determine annual owning and operating costs—is commonly employed. However, the Present Worth comparison technique was preferred for this study due to the simpler evaluation of the inflation factor. It also simplified display of the study’s conclusions. In the Present Worth method, the value of operating cost over the entire equipment life or selected payback period is converted to a single premium annuity or initial sum set aside to cover operating cost. That portion of the initial sum set aside for future operating costs can be invested. It can be presumed that the retained amount Fe b r u a r y 2 0 0 9 H ad a survey of air conditioning engineers been conducted in 1950 posing the question: “What face velocity do you choose in selecting central station air handling units for air conditioning?” the predominant answer would have been, “500 feet per minute.” Should the same question be posed today, few would be surprised to hear the answer. Yet few would question that the major shifts in equipment, labor and energy costs and the growing concern for energy conservation are likely to have altered the validity of this “ancient” rule of thumb. This paper will test the old rule and see if some new ones should take its place. To make a proper judgment in the selection of equipment, all significant economic parameters must be considered: First costs, operating costs, interest rates on invested capital, inflation rate, desired payback period and equipment life have been selected for this study. Quotations were obtained on various air handling components and discounted to simulate competitive bidding. Labor costs were added to equipment cost. Both were marked up to include subcontractor and general contractors’ overhead and profit arthur e. wheeler, P.e., Fellow aShrae Arthur E. Wheeler worked 11 years for Carrier Corp., then served almost 30 years as senior vice president for Henry Adams, inc., Baltimore. He formed his own consulting engineering practice 1987 in towson, Md. He joined ASHRAE in 1960 and served on many iAQ-related committees over the next 40-plus years. this included service as a member of the Standard 62 project committee, tC 9.1. on large building air conditioning and as chair of the 1996 ASHRAE iAQ Conference. Wheeler also held all offices in the Baltimore chapter. He received the ASHRAE distinguished Service Award in 1978. He died in 2008 at the age of 81. 40 ASHRAE Journal a s h r a e. o rg

ASHRAE Journal - February 2009

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