Wednesday, May 15, 2013

The Light Bulb Efficiency Lie

With the economy still in questionable shape and people's real income stagnant, people are still looking for ways to cut their expenses. If your budget looks anything like ours, utilities are in the top five most expensive monthly expenditures. We are going to look at lighting of the home as a part of this expense. We are going to discuss how much of my family's electric bill goes to lighting and how little changing the bulbs in our home will effect this.

I will quickly admit that this was not the article that I was expecting to write. I was expecting to compare the different types of bulbs and tell you how long it would take for us to save the difference in price. After doing the math I have realized that lighting is the smallest part of our electric bill. I will still go over the savings, but not with the same zeal as before.

There are some terms we need to be familiar with when shopping for light bulbs.

Lumen: Quite simply a measure of brightness. The higher the number the brighter the bulb. Incandescent bulbs produce around 16 lumens per watt. A 100 watt incandescent bulb produces 1600 lumens.

Kelvin (K): This when used with light is the color scale. Interestingly Kelvin is a measure of temperature. The lower the number the "cooler" the color. A bulb with a 3100 K color will be called a soft white bulb. For me, the soft white looks very yellow. A bulb with a 6100 K color will be called a natural daylight. To me the natural daylight looks sort of blue. The natural daylight bulbs appear brighter even though it uses the same amount of energy.

Kilowatt Hour: Your electric bill is measured in kilowatts or kilowatt hours. A Kilowatt is 1000 watts. A Kilowatt hour is the amount of work 1000 watts can do. For the purpose of our discussion we will treat them as being exactly the same thing. A 100 watt incandescent bulb will burn a kilowatt in 10 hours.

Our electricity costs us 7.7 cents per kilowatt with a minimum bill of $14.50. To find what you are being charged per kilowatt, take your utility bill and look at it closely. Some of the bills will tell you exactly what you are being charged by kilowatt. Some you will have to figure yourself. You take the amount of your bill, subtract any taxes and fees. Then you take the amount that is left and divide it by the number of kilowatt hours used that month. This will give you cost of each kilowatt.

At 7.7 cents per kilowatt it costs us less than a penny an hour to run a 100 watt incandescent light bulb. With an average daily usage of 4 hours for several of the fixtures in our house and most of these having 3 bulbs per fixture. This means we are spending $25.87 a month only on lighting. I was quite shocked that this number was that small, but I figured it 3 times. This was figured on 28 bulbs running 4 hours per day, if you operate more lights than this the savings will be greater.

Incandescent: Incandescent bulbs have been the standard for a very long time. Incandescent bulbs have the shortest lifetime of any of the bulbs we will talk about today. They burn hot, so hot in fact that when I was a child I would melt crayons on the bulb of the light in my room. If there are any children reading this...Do Not Melt Crayons On Your Lamps. 

Halogen: Halogen bulbs have a slightly longer lifespan than the incandescent bulbs. A 100 watt equivalent burns 72 watts. If you changed out all 28 of the bulbs to halogens in my example, the monthly cost would go down to  $18.62 per month. Halogens burn very hot, so hot that I have considered changing all of the bulbs to halogens during winter because I believe the heat they produce would decrease heating costs. I would most certainly take any halogens out during summer months.

Compact Florescent (CFL): Compact Florescent bulbs have become the standard bearer of energy savings. They burn cool, last up to 3 times longer than an incandescent and a 100 watt equivalent only burns 24 watts. If we were to change all 28 of the bulbs to compact florescent bulbs instead of incandescent bulbs the price of lighting would go from $25.87 to $6.21. This is a significant savings. The biggest drawback for me is most of the CFLs contain mercury, which if not properly disposed of can be very damaging to the environment.

LED Light Emitting Diode: The newcomer to the market is the LED. LEDs are the most efficient, burn the coolest, and last the longest. Most of the models claim to be able to last 25 years. A 100 watt equivalent burns between 14 and 20 watts. For a bulb that would fit in most standard fixtures, we would need the 20 watt version. Changing all of the bulbs from incandescent to LEDs would drop the electricity cost for lighting from $25.87 to $5.17. This sounds great until you realize that a standard looking LED that would fit in most fixtures cost ranges between $33 and $50 each. If you have the money to drop on these bulbs it would be best for the environment and you wallet if you are willing to look extremely long term. Some estimates say that it will take 8 to 10 years to make up the difference in cost. My estimate is right at 4 years with the exact same usage as I figured. In our household this is not possible because our lighting usage goes way down in the summer so this number would be much greater.

Conclusion: The 100 watt light bulb being phased out is a way to act like you are doing something without actually doing so. For most households lighting is the smallest part of their electric bill. If you are wanting to really reduce your electric bill adjust your thermostat. Heating and cooling is estimated to be as much as 20 percent of your total utility bill. Be aware of how much television you are watching. The average electricity a television uses is 300 watts per hour. Use a clothes line to dry some of your clothes.The average clothes dryer uses 4400 watts per hour. There are more and better ways to save on your electric bill. Having said all of this, I am still looking forward to the price of LED bulbs coming down and I want to have them in my home, but I am not willing to pay the difference.

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  1. When I replaced my incandescent bulbs with CFLs, and my CRT monitors with LCD/LED monitors, my electric bill dropped from $80 to $40/mo. Its worth noting that we were using the lights for about 16 hours a day because my insomniac wife needed them overnight, and used them during the day because she refused to open the blinds. Ahem. Not a healthy situation.

    Heating water, by electricity, is often the biggest expense in a home. A good efficient water heater with a blanket wrap around it and the hot water pipes where exposed will help a lot.

    A well maintained and very clean refrigerator coil needs dusting so it can exchange the heat and cool efficiently. So either clean it or replace it with a more efficient modern fridge to cut your 2nd biggest power demand.

    Big Screen plasma TVs are famously huge power sucks. Make sure what you're watching on them is important, since they wear out by the hour in most cases. LED computer monitors are famously small power demand. Watch on the monitor instead, if you can. Wireless internet network systems suck lots of power. Hardwired cables are both faster and lower energy and can't by hacked in 12 seconds by passerby with a laptop.

    Every one of those heavy fist-sized transformers you plug into the wall to run some electric device is using power even when the device isn't running, due to how they work. Put those on a power strip and turn the strip off when not in use. Those are wasting power, all of them.

    Most music amplifiers suck power when they're on, due to the charged capacitors, even if you're only using a fraction of that power to make sound. On demand subwoofers do that too, and you don't usually turn those off if they have their own Amplifier.

    An MP3 music player uses a fraction of the power of a speaker music system and costs a fraction as much to buy in many cases, as long as its not an Apple Product anyway. I recommend the kind that uses disposable batteries since they are like brand new every time you replace the battery, rather than give you less and less value. And the music keeps playing when you're weeding in the garden or washing the car. You can also put audio books on them, since by law they have to be offered at libraries (services to the blind).

    Most people would save more money by simply switching from smartphones with data plans ($250 for a family of 4) to pay as you go plain phone services ($24/mo) and small data pads with wireless connectivity since Comcast and ISP/cable TV services like it will let you use your standard user and password to their system on their wireless hubs, going on poles in most towns. Eventually, that will make the cellphone a purely rural device and you can skype from a data pad. I see a real future in 7 inch extremely durable data pads with this and WiMax connectivity, assuming they can solve the battery issues.

    Now consider the cost of driving an SUV in modern $3.90/gal gasoline to the power savings from CFLs every month. Ouch?

  2. I'll try to remember not melt crayons on my lightbulbs! LOL! We switched to CFLs in most of our fixtures (huge house with a lot of lights burning all at once because of the "great room" concept - which I find I don't care for). It made a huge, huge difference in our light bill, but they do *NOT* last seven years. They don't last any longer than regular bulbs but are more expensive to buy. So when you add the cost of replacement, the savings really aren't quite so significant. And I definitely prefer the light given off by an incandescent bulb. I left inc. bulbs in my reading lights - like my night stand and next to a couple chairs in the family room so the harsh glare won't bother me.

    1. Hi Erin, glad you are here. I have found that for me anyway, if you get the natural daylight bulbs for your reading lights they work much better. I have found like you that they really do not last much if any longer.

    2. Oh and by the way, it is an honor to have someone I listen to read my work.

    3. My CFL's often do last a couple years, especially in areas where they stay on for long periods. Incandescents in those areas only last a few months. Back when CFL's were first available (and then mostly by mail-order in specialty catologues), I remember reading an article about HOW bulbs wear out and whether you should leave the light on if leaving the room for a few minutes. The conclusion was that with incandescents, you should almost always turn off the light unless you will be back in less than 5 minutes. Their lifespan is mostly limited by how long electricity is flowing through the filament. The lifespan of the ballast on CFL's, is decreased every time the bulb is turned on, so in balance, you would be better to leave CFL's ON unless you would be out of the room longer than 20 minutes. With that info, I decided to first use CFL's in fixtures that were kept on for longer periods of time and avoided them in the ones that were more likely to be switched on and off all day.

  3. Thank you for posting this *great* info on the HomeAcre Hop! I hope you'll come back on Thursday:

  4. Hi,

    60 Watt Incandescent Light Bulbs are for your home and office, the above points are most important for you. Thanks a lot.