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# Annual Cost Of Lighting Calculator

Calculates the annual cost of operating a light bulb.

cost: The annual cost of operating the light.
lamp \$: The cost of the lamp (bulb), including installation.
watts: The lamp wattage.
\$/KWH: The electric rate, \$/KWH
hrs/day:The hours per day the lamp is on.
life: the life of the lamp in hours.

## Example 1

Calculate the cost per year to operate a 825 lumen, 60 watt incandescent light bulb for 3 hours per day.

Value Keystrokes Display Description
1 lamp \$ 1.00 Stores the lamp \$ value.
60 watts 60.00 Stores the watts value.
.15 \$/KWH 0.15 Stores the \$/KWH value.
3 hrs/day 3.00 Stores the hrs/day value
1000 life 1000.00 Stores the life value.
cost 10.95 Calculates the annual cost to operate.

## Example 2

Calculate the cost per year to operate a 800 lumen, LED light bulb for 3 hours per day.

Value Keystrokes Display Description
5 lamp \$ 5.00 Stores the lamp \$ value.
8.5 watts 8.50 Stores the watts value.
.15 \$/KWH 0.15 Stores the \$/KWH value.
3 hrs/day 3.00 Stores the hrs/day value
10000 life 10,000.00 Stores the life value.
cost 1.94 Calculates the annual cost to operate.

Entering 0 for lamp \$ gives you the energy costs per year.

Entering 0 for watts gives you the lamp costs per year.

The hrs/day is an important value to consider. If the lamp is in an area where it is only used a few hours per year it is hard to justify an expensive, energy efficient lamp. For outdoor dusk to dawn lighting (13 hours per day) low wattage and lamp life are important.

Add a "cost" of installation to the light bulb cost where the light is difficult to reach. This usually involves a ladder to reach the light bulb.

You can make a copy of this calculator to quickly compare between two different types of lamps.