HOME ENERGY AUDIT: ENERGY EFFICIENCY WORKSHEET

Created for the NTEP II program on behalf of the National Renewable Energy Laboratory in Golden, Colorado.

1. If model A uses 700 kWh/year, how much is the yearly operating cost (based on a cost of $.089 per kWh)?

700 kWh/year x $.89 /kWh = $62.30

2. What is the lifecycle cost of model A if it cost $789?

$ 789.00
+ 946.96 (62.30 x 20 x .76) or yearly operating cost x estimated lifetime x discount factor
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$1,735.96

3. If model B uses 900 kWh/year, how much is the yearly operating cost (based on a cost of $.089 per kWh)?

900 kWh/year
x $ .089 /kWh
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= $80.10

4. What is the Lifecycle cost of Model B?

$ 700.00 (purchase price)
+ $1217.52 (80.10 x 20 x.76)
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$ 1,917.52

5. If model A costs $789 to buy and model B costs only $700, what is the payback period?

(Difference in purchase price between A & B models) / (Difference in annual operating cost)

$ 89.00
---------- = 5 years for the payback period
$ 17.80