The Doorbell Dilemma
In This Issue
Subscribe
Receive your own copy of The Energy Miser
Handy Links
 
Dear Reader,

The Energy Miser #22 September 1, 2008

Yes I know I was supposed to write about radiant floor heating and solar space heating but something came up. Hopefully, you'll find this substitute subject as interesting. - Mark

Read all past issues of The Energy Miser here.

Do you have an electric doorbell? Is it running? Than you better go catch it. Or even better, disconnect it.

If your home is like mine, your doorbell is electric. Why electric? Who knows. But from what I've been able to find with Google, electric doorbells started to become popular in the early 1900s. Back then, we probably didn't think much about the electricity cost or environmental impact of a doorbell. Not any more.

Do doorbells use a lot of electricity? It depends on how you value the role of doorbell. If there was no other way to alert you to a guest at your front door, then it would seem like the energy used to run a doorbell is well spent. But there are a number of low energy ways to alert you of visitors....
How does an electric doorbell work? It's pretty simple. When a visitor presses the doorbell button, the button closes a circuit sending electricity from your circuit panel to some sort of noise making device - a buzzer, a solenoid-struck chime, or perhaps an electronically generated tone or tune.

Nowadays, most doorbells run on 24 volt AC Current. This was likely done for safety reasons and it makes sense. Doorbell buttons are outside and often get wet. Should you ever have a "short" in the doorbell button, your guest won't get electrocuted (they may be shocked if you come to the door naked however - insert rim shot here :-)

Unfortunately, US homes are wired for 120/240 volt AC current. So to get the voltage down to 24V, when the electrician installed your doorbell, he or she also installed a transformer in your circuit panel like the one in the photo.

In the photo, you see the transformer (large silver/gray thing) and wires. On the right side of the transformer are red and white wires. Those run to my doorbell in the front hallway. From there wires run to my doorbell buttons (oddly, I have a button at the back door too).

On the left side of the transformer are white and black wires. They are connected into my circuit panel.
If you've followed my writing, you know that transformers are "phantom loads" and use power all the time, whether the device they power is on or off. Furthermore, many doorbell buttons have lights behind them. Naturally lights use power too. I wanted to figure out how much power my doorbell was using. So I got out my trusty Kill-A-Watt.

In order to measure power usage with the Kill-A-Watt however, I had to disconnect the doorbell from the circuit panel and put a plug on it. Then I plugged the doorbell into the Kill-A-Watt and plugged the Kill-A-Watt into the wall.

The Kill-A-Watt did its thing and in a few seconds, I was shocked (not electrically :-) to learn that my doorbell transformer and button lights draw a total of three watts of power. That's 3 watts 24 hours a day, 365 days a year.

One year is 8,760 hours. 3 watts x 8,760 hours / 1000 = 26.28 kilowatt-hours to run my doorbell. At my electricity rates that's about $3.15. Not much right? Let me make it more interesting...
There are about 5,000 homes in Hudson. Lets assume that 80% of the homes have working doorbells. 80% x 5,000 = 4,000. Let's also assume that all the doorbells draw 3 watts (I bet the older ones draw more). 4,000 x 8,760 x 3 / 1,000 = 105,200 kilowatt hours per year - enough electricity to power 10.5 average homes for a year. Ouch.

Want scarier? As of the year 2007, the US Census estimates that Massachusetts has approximately 2,700,000 households. Again, assuming 80% have working doorbells like mine, that's 2,160,000 doorbells using 3 watts of power. 56,764,800 kilowatt-hours or 56.7 megawatt-hours of electricity to run Massachusetts' Doorbells. Enough to power 5,676 average homes for a year (all of Hudson's homes in fact).

How about the nation? The US Census estimates 127,901,934 homes. Using the same 80% assumption, that's 2,689,010,261 kilowatt hours. Enough power to run about 268,900 average homes for a year. (95% of the homes in Alaska or 100% of the homes in Wyoming).

Nationwide, each kilowatt-hour of generated electricity is responsible for about 1.34 lbs of carbon dioxide. 2,689,010,261 kilowatt-hours leads to 1,801,640 tons of carbon dioxide in our atmosphere... for doorbells.
When you next visit my home, please use your fist, shout, or use the knocker; It's a bronze acorn in the middle of my front door. Don't go to the backdoor, that doorbell no longer works.











And, in case you forget, there's a sign above the doorbell button out front:

Here is how I disconnected my doorbell. Please do not try this at home. There is a risk of shock (electrical).

First I took the cover off of my circuit panel. Then I found the transformer. From the transformer, I traced the wires. As I mentioned above, two wires (combined in a brown sheath) take a path out of the circuit panel. Those wires end at the doorbell in my front hallway.

On the other side of the transformer, were a black and a white wire. The black wire connected one contact on the transformer to a circuit breaker. In the picture above, it's the bottom wire. Because doorbells draw very little current, the electrician "doubled up" the doorbell wire on a circuit breaker rather than giving it its own breaker.

Using an insulated handle/blade screwdriver I loosened the screw holding the wire and pulled the wire out and made sure it didn't touch anything else in the panel.

The white wire was attached to the "Neutral Bus." Removing this wire was a bit tricky because the neutral bus is behind the wires feeding into the circuit breakers. I used a screwdriver with an insulated blade.

After disconnecting both the white and black wires, I disconnected the red and white wires from the other side of the transformer. I coiled those wires up and tucked them into the corner of the circuit panel away from any live circuits, removed the transformer, and closed up the circuit panel.

Again, don't try this at home (unless of course, you are an electrician or you stayed at a Holiday Inn Express last night :-)
Did you know that cooling your attic reduces your cooling load in the summer? Now you can cool your attic without using paying for electricity.

Since we are up on roofs a lot, we've decided to add installation of solar powered attic fans to our list of services. You can learn more about the fans at http://www.sunrisesolar.net/index.htm

Call or write for an installation quote.

Disable your doorbell, reduce waste, use a fan instead of an air conditioner, turn off the lights, switch to compact fluorescent bulbs, put computer gear on a power strip and turn it off at night, unplug unnecessary appliances, ventilate your attic, take shorter showers, walk instead of drive, ride a bike, group your errands, inflate your tires, grow your own food, eat locally-produced food, recycle, use your most efficient vehicle, get a hybrid vehicle, wash your clothes in cold water, buy less packaging, use a clothesline instead of the dryer, drink tap water, print with narrower margins, use both sides of the page, buy less, compost, install a renewable energy system...

Thanks for Reading the Energy Miser,
Mark Durrenberger
New England Breeze, LLC

phone: 978-567-WIND (9463)