The biggest weapon in your arsenal to battle high energy bills is the ability to measure. Most holiday lights have no electricity consumption rating on the package (as our 100W lightbulb example), so how do you begin to make any calculation? You can find a P3 Kill A Watt meter (or something similar) for about $30 at any hardware store, and these handy devices can tell you how many watts a particular appliance is using and have many other uses. For example, it can tell you how clean the outlet power is, and can be used to sum up electricity needs when shopping for a generator. In my line of work, it is an essential tool when measuring the efficiency of PC power supplies.
Say Watt?
Most electric companies measure electricity (and bill) by the Kilowatt Hour, and where I live this costs 0.7269 cents. A Kilowatt hour is the cost of running 1000 watts for one hour. Our 100W light bulb will have to run for 10 hours to reach 1 Kilowat of usage (100 x 10 = 1000). So if you run that light bulb 24 hours a day, 7 days a week for a full month then that bulb will cost you $52.33.
100W x 24 hours x 30 days / 1000 = 72 Kwatt hours
72 Kwatt Hours x 0.7269 = $52.33
Now that you have a tool to actually measure, then you need to go around the house and test. You’ll be surprised at how much extra electricity is being used during the holidays. Below are the consumption results from several decorations around our house:
| decoration | Wattage |
| 7′ Christmas Tree (400 mini bulbs) | 296 W |
| 7′ Pre-lit Christmas Tree (350 mini bulbs) | 243 W |
| Outisde display of 75 C7 lights + 200 incandescents: | 640 W |
| 3′ pre-lit christmas tree (75 mini bulbs) | 50 W |
| string of 30 incandescent bulbs | 25 W |
| Snowman with 2 C4 bulbs | 14 W |
| 600 LED String Lights | 4 W |
LED lights use about one-tenth the electricity of incandescents
It actually shocked me (figuratively, not literally) when I took these values. These measurements mean that each lit Christmas tree is the equivilant of a high-end PC… now imagine the extra costs of running three or four PCs nonstop for a whole month. You can see that LED lights use significantly less electricity than lights that use incandescent technology, because LEDs are about 98% efficient. Using our same formula it costs $1 to run LED lights for an entire month, as opposed to $30 for comporable string lights.
