Question

An air-conditioner with air-cooled evaporator costs $50,000. With EER of 2.16 kcal/h W it is estimated to use 140 kWh of electricity daily on an average day requiring cooling. Similarly, a new type of air-conditioner employing evaporative cooling condenser costs $120,000. The EER of this air-conditioner is 4.66 kcal/h W and is estimated to use 75 kWh of electricity and 750 liters of water daily on an average day requiring cooling. The former air-conditioner would have a useful life of 10 years while the latter air-conditioner would work for 12 years with an extra maintenance cost of $1,000 a year. Both products would have no salvage value after their useful life. Consider in Hong Kong, the cost of electricity is $1.197/kWh and water costs $4.58/m3, calculate the breakeven number of days of use for the 2 types of air-conditioners if the MARR is 8% p.a.

Answer 1

As we can see that taking into account all the recurring costs throughout the life of both the machines,  air-conditioner 2 will save us $76,507.65 in today's worth by cutting down on the electric cost