In a local store, find the price of a 60-W incandescent bulb and CFL and
LED bulbs with an equivalent light output. Based on a use of 4 hours per day and an electricity cost of $0.11/kWh, calculate the payback period for each of these bulbs compared to the incandescent.

Question

Quizplus · Accepted Answer

The Answer is At a local department store the following items are found package of four

60 \mathrm {~W}

incandescent bulbs at

\$ 1.12

(or

\$ 0.28

each) package of six

13 \mathrm {~W}

CFL bulbs at $9.97 (or \$1.66 each) package of one

9 \mathrm {~W}

LED bulb at

\$ 24.99

Daily savings for four hours of use for the CFL (compared to the incandescent bulb) is

0.06 \mathrm {~kW} - 0.013 \mathrm {~kW} ) imes ( 4 \mathrm {~h} ) imes ( ( \$ 0.11 / \mathrm { kWh } ) = \$ 0.0207

and for the LED the daily savings is

( 0.06 \mathrm {~kW} - 0.009 \mathrm {~kW} ) imes ( 4 \mathrm {~h} ) imes ( ( \$ 0.11 / \mathrm { kWh } ) = \$ 0.0224

The additional initial cost for the CFL and LED bulbs over the incandescent is

\$ 1.66 - \$ 0.28 = \$ 1.38

and

\$ 24.99 - \$ 0.28 = \$ 24.71

, respectively. The payback periods is

\$ 1.38 / \$ 0.02068

per day

= 67

days for the CFL

\$ 24.71 / \$ 0.0224

per day

= 1100

days (about 3 years) for the LED

In a Local Store, Find the Price of a 60-W