How to calculate the energy savings of LED Christmas lights
June 16, 2008
We frequently help our customers analyze the cost savings that can be achieved by using LED lights instead of incandescents. The calculations to determine the cost savings are not very complicated but it is a lot easier with a good conversion calculator handy. Our Energy Scrooge Calculator provides some interesting information about the benefits of LED lights but we've ever written about how to calculate the exact savings one can expect by replacing their old incandescent Christmas lights with LED lights. Here's the data you will need to perform this calculation:
1. Total # of bulbs;
2. Wattage of the individual individual incandescent bulbs to be replaced. (C9s are generally about 8-9 watts; C7s are generally about 6-7 watts; and mini lights are usually between .50 and 1 watt;
3. Amount of time bulbs will be illuminated; and
4. The average cost of a kilowatt hour of electricity in your area. ($.10 is typically a safe number.)
Step 1: Calculate total watts
Multiple the total number of bulbs by the wattage of 1 bulb. This equals the total watts of the display
Step 2: Enter data into conversion calculator
Enter the product of the formula in Step 1 into the "Watts" field in this calculator. Next, enter the total amount of time the lights will be illuminated in the "Time" section of the calculator. (Note that the time can be in seconds, minutes, hours, days, months, or years.)
This calculator will calculate the total kilowatt hours consumed by this lighting display.
Step 3: Determine cost of electricity
Multiple the total kilowatt hours the display will consume (as determined by the calculator in Step 2) and multiple it by the average cost of a kilowatt hour of electricity in your area. The Department of Energy website has statistics on the average cost of electricity.
Step 4: Determine to cost to operate Christmas lights using LEDs
Repeat steps 1-3. The average LED holiday style light is between .05 and .07 watts.
Step 5: Calculate the savings
Subtract the cost of operating the LED lights from the cost of operating the incandescent lights. This is the total cost savings you can expect by switching to LEDs.