It’s that time of year again when the Christmas tree lights come out of storage and houses all across America are aglow with festive decorative lighting. This year with advances in LED lighting I wondered how much energy could be saved using LED decorating.

**Note: This post sparked some debate so I have edited it to include some real world numbers from our own holiday decorating last year. We used incandescent bulbs last year and I had no idea how much energy they would be using. I will be using figures for LED bulbs from www.HolidayLEDs.com for my calculations.

I found myself asking… How much energy could we save using LED lights for decorating our house?

Calculating LED Decorating Savings:
Lets assume the incandescent bulbs use about 6 watts per bulb, the LED replacement bulbs which will allow reuse of all the cabling can run at just less than 1 watt per bulb;

Quote from HolidayLEDs.com: Both the C7 and C9 retrofit bulbs use only .96 watts per bulb and will last for 50,000 hours or more. Our retrofit replacement bulbs can be used with any standard C7 or C9 socket wire.

Now lets also assume the lights are lit up from 8PM till midnight, i.e. 4 hours of use each night.
Now lets assume the cost of electricity is $0.10 per kilowatt hour.

http://www.flickr.com/photos/david_gray/ / CC BY-NC 2.0

Let's assume 1000 bulbs to decorate a typical roofline

In my original post I quoted 1000 bulbs to light up the typical roofline, after some of the comments we received I went out and counted the number of bulbs we used to line our house last season, our home is 2600 sq ft and we used approx 400 bulbs… We can start our energy calculations from there;

Energy Used and Cost for Incadescent Lights:
400 x 6 watts = 2400 watts or 2.4 kilowatts. This equals 9.6 kilo watt hours which would cost $0.96 per night of illumination. (This is much less than I had originally quoted and is much more realistic for the typical home)
Let’s say the lights are lit for 30 nights over the holidays, that would be a total energy usage of 288 kilo watt hours at a total cost of $28.80 in electricity for a month.

Energy Used and Cost for C9 size Screw in Replacement LED Lights:
400 x 1 watt = 400 watts or 0.4 kilowatt. This equals 1.6 kilo watt hours which would cost $0.16 per night of illumination!
Let’s say the lights are lit for 30 nights over the holidays, that would be a total energy usage of 48 kilo watt hours at a total cost of $4.80 in electricity for a month.

I was amazed, the grand total using LED lights on a house in place of incandescent bulbs for the above example would realize a saving of $24.00 for the month of December.

The savings would be even bigger for larger homes, imagine how much you could save if you lived in a castle! The picture below is of an energy efficient sleeping beauty castle which Disney has decorated completely with energy efficient LED lights.

http://www.flickr.com/photos/masteryofmaps/ / CC BY-NC 2.0

The Savings Can Be Huge Especially for Larger Homes

But How Much Would LED Decorating Cost?
At the moment it would probably cost about $50 for a string of 25 LED C9 size bulbs which would cost about $800 for 400 bulbs so this is definitely not going to save you money, it would take 33 years to make back this money from the energy savings but that isn’t the point!

LED bulbs save so much energy, they could save you around 60 kilowatts for a typical holiday season of illumination!

To put this in perspective, the 60 kilowatt saving (240 kilowatt hours over the 30 days) would be the energy produced by burning approximately 7 gallons of gasoline. So with the energy you save using LEDs over a single holiday period you could drive a 50 mpg Prius 350 miles!
So this holiday season, if you walk around a local parade of lights, make sure you give extra praise to families who have invested in LED decorations, they’re saving energy and the planet.

P.S. Thanks to everyone who commented on this post, it made me take a hard look at my calculations and the above post reflects multiple corrections!

Martin Energy Usage, Green Power, Home & Garden energy, led lights, reducing