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Two types of air conditioning systems are under consideration for a building und

ID: 1212815 • Letter: T

Question

Two types of air conditioning systems are under consideration for a building under construction, financial information and operating characteristics of the two AC systems are summarized as follows: Assume that the AC will be operated 2,000 hours annually, the electricity cost is 10 cents per KWh (1HP = 0.746KW), the MARR is 10%. a) Determine the capital recovery cost, annual electricity cost for both models b) Determine the unit cost for each model (i.e. cost per operating hour), based on the unit cost, which model should be selected? c) Determine the breakeven annual operating hours

Explanation / Answer

Formula AC Model A AC Model B Price ($) P               16,000               10,000 Service Life (Years) SL                       10                       10 Salvage Value ($) SV                 5,000                 2,500 Operating & Maintenance Cost Per Year ($) OMC                     350                     300 Output (HP) OHP                     150                     150 Output (KW) OKW=OHP*0.746                     112                     112 Efficiency E 90% 85% Input (KW) IKW=OKW/E               124.33               131.65 Annual Operating Hours AOH                 2,000                 2,000 Electricity Cost Per KWh ($) ECPK                      0.1                      0.1 Annual Electricity Cost ($) AEC=IKW*AOH*ECPK               24,867               26,329 Minimum Acceptable Rate of Return (MARR) MARR 10% 10% Net Cost ($) NC=P-SV/(1+MARR)^SL         14,072.28           9,036.14 Capital Recovery Factor CRF=((1+MARR)^SL*MARR)/((1+MARR)^SL-1)                    0.16                   0.16 Capital Recovery Cost ($) CRC=NC*CRF                 2,290                 1,471 Cost Per Operating Hour or Unit Cost ($) UC=NC/AOH                          7                         5 Breakeven Annual Operating Hours BEAOH=OMC/UC                       50                       66 Selected AC Model (Based on Unit Cost) AC Model B