Life-Cycle Cost Analysis

Energy Efficiency and Life-Cycle Cost Analysis

Life-cycle cost (LCC) analysis is the most rational, objective method for selecting the optimum HVAC system for a laboratory facility. Through LCC analysis, all factors that influence total system cost can be identified and quantified. Subjective factors such as fuel cost adjustments, component reliability, and maintenance costs are also included. LCC analysis can be used to assess the economic consequences of any decision by comparing two or more alternatives. [Lacey, 1993; Matson, 1990]

Review of the annual cost of space conditioning for a laboratory or cleanroom shows the high impact of energy costs. A Class 10,000 cleanroom system costs five to 10 times as much to operate annually as the conditioning system for the facility's office spaces; a Class 100 laboratory cleanroom system will cost 50 times as much. In either case, however, the contributions to total cost are:

·energy costs, contributing 65 to 75 percent;

·capital costs, i.e. interest plus depreciation, contributing 15 to 25 percent; and

·maintenance costs, contributing 10 percent. [Schicht, 1991]

A life-cycle cost analysis does not need to be extremely complex to yield reasonably accurate figures for first and operational costs. A modified LCC, similar to a simple payback, does not account for inflation or cost of money; this modified LCC can give an order-of-magnitude appraisal to help determine whether or not to add an EEM to a system. [Basso, 1997] [Kruse, 1991; Lacey, 1993]

If LCC computations are easily understood, the analysis is more likely to be used by design teams and accepted by researchers/owners. One approach to simplifying life-cycle cost analysis is to convert facility operating costs to an equivalent annual expense per fume hood. This number can serve as a common denominator for comparing the composite performances of various system designs and for examining the sensitivity of each design alteration. The energy engineer should concentrate on determining realistic values for the most sensitive design factors before selecting the HVAC system type. [Lacey, 1993]

LCC factors that influence a laboratory's HVAC system design can be broken into three categories: design factors, economic factors, and performance factors. Sometimes other factors must be considered; for example, a functional-use factor may be developed based on efficiency studies of personnel in the operations of different laboratory systems or components. Because laboratory personnel LCCs are very high, the more functional a design or system is, the more LCC savings are possible. An example is the workspace flexibility and reduced costs of space planning that can be afforded by a raised floor system. (see Chapter 2) [Matson, 1990; Lacey, 1993; "Minimizing Life-Cycle Costs—and First Costs—of New Building Systems," 1994]


LCC design factors

LCC economic factors

LCC performance factors

LCC and VAV vs. CV

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