I wrote a post on Facebook (funny how I seem to be getting more and more blog entry ideas for post on Facebook) about light bulbs and had a light bulb moment. How many people need a simple primer about what a simple light bulb is and how they work? How many people know all the stuff that goes into determining what a good light bulb is? There was a time not too long ago when I didn’t know all this stuff, but I am a geek and looked it all up, and so I thought I would pass on to you what I learned in a simple manner so you too can be a green geek light bulb fanatic.

Some Terms

Let’s start with a few definitions so we are all on the same page with our terminology. This involves more than you may realize:

Light Bulb: A fixture that can be socketed into an electrical receptacle that has some sort of bulb or tube from where light is emitted. The can be large, small, round, straight or even solid, but the shape does not matter as long as it emits light. The correct terminology for a light bulb is “lamp”, but we will use light bulb so as not to confuse it with the thing you set on your night stand.

Watt: This is an amount of energy that is used to run your light bulb.  One Watt (named after James Watt) is about 1 joule per second of power. The number of Watts used has nothing to do with how bright a bulb is, just that amount of energy used. So get it out of your head that a 100W incandescent bulb is the same thing as a 100W compact florescent bulb, one would put out WAY more light than the other. The shorthand for Watt (or technically Watt Hour) is a “W”.

Average Life: This is how many hours you can expect the light bulb to last. It could be as little as 10 hours to more than 60,000 hours depending on the type and use. Your average 60W household incandescent light bulb last about 1500 hours (about 64 days of continuous use) before it will likely need replacement.

Lumens: This is how bright the bulb is. One lumen is about as bright as one candle light. Your standard 60W incandescent light bulb puts out about 750 lumens. When we talk about how bright something is it will be in lumens.

Kelvins: This is sort of a tricky one. This refers to the temperature which the light bulb burns to create light. The higher the temperature the closer to “daylight” the light is. If you look at your standard 60W light bulb you can buy at most stores for about a buck a bulb, they shed light at about 2800K. That means the filament inside the bulb gets to about 4600f degrees. That hot, but it sheds a yellowish light. But if you go find a “daylight” bulb (maybe because you have seasonal affective disorder) this is a 6400K bulbs and “burns” at 11,000f degrees, about what the sun’s surface temperature is, and why 6400K bulb is like sunshine.

Incandescent Lamp: This is the type of light bulb Thomas Edison invented in 1880 (actually he invented the first practical light bulb. Humphrey Davy, an Englishman invented the first light bulb in 1806, but it would not shine long at all). Basically it is a metal filament that glows brightly when electricity is passed through it. More specifically, the glass bulb encloses a vacuum and a tungsten metal filament. There is a correlation between Kelvins and average life of the bulb being the higher the Kelvins then generally the shorter the life span. This is why “daylight” bulbs are so expensive; they need to be much heavier duty to last longer.

Florescent Lamp: This is a whole class of bulbs that work by passing electricity through a gas vapor that then glows (the glow is called plasma) invented by Edmund Germer in 1927. These bulbs are you ordinary florescent tubes like you may have in a kitchen or garage, the new compact florescent tubes that are mostly what this article is about, neon signs, sodium/mercury vapor lamps and several others. The details on how they work are not important, but you should know that they are about six times more efficient than incandescent lights and they generate very little heat. This makes them environmentally friendly except for the mercury that must be in each one.

Light Emitting Diode (LED): Nick Holonyak created the first LED in 1962. This happens as an electron fills a “hole” in a cathode from an anode and doing so emits a photon. It’s all got to do with Quantum Physics and would recommend you look it all up if you are interested, it is very fascinating. Recent developments have led to the HPLED (high power light emitting diode) and make it possible to use this technology as everyday lighting. This is the next generation of lighting and will replace CF bulbs because they do not require mercury to run.

Seeing the Light

Ten years ago we didn’t have to think about all these things because a 60W bulb was a 60W bulb and we all knew how bright that was. Maybe we needed a bulb that was softer for decoration and looked for a 40W bulb. The kitchen was a place where it was advantageous to have a 100W or 150W bulb and this was how we thought about it, it was all sort of standard. The same thing applied to fluorescent tubes, there were some standards and that was it. We never really thought about how much electricity a bulb used until utility rates really started to climb.

With the new compact fluorescent bulbs (the ones that look like twisty pig tails) we need to know more about them to know what we want. Let’s start by understanding a regular bulb. A 60W bulb puts out about 750 lumens of light at the cost of 60 watts of power an hour. That means that in 16.6 hours that bulb will use one kilowatt. To put this in perspective, if you left one 60W light on all the time in one month it will use a little over 43 kilowatts hours(kWh).  Taking into account peak and off peak power prices my average cost per kWh is about $0.32. That means the cost to run one light bulb 24/7 for a month is about $13.75.

Now let’s look at the cost for a compact fluorescent bulb (CF). A 13W CF puts out about the same light as a 60W incandescent bulb, 750 lumens. If you run this bulb 24/7 for a month it will use 9.36 kilowatt hours. Using the same price for power as above, running a CF bulb costs just under $3.00 a month. Using a CF saves me $10.75 a month just in power costs. Considering I paid only $0.40 for the bulb (they were on special at Lowes) I have actually paid for all the 13W CF bulbs that replaced my old 60W with a few extra bulbs in case some fizz out early. And that is just one bulb for one month; imagine how much I am saving by using all the bulbs?

I replaced 4 75W spots in the kitchen with 4 13W CF. I replaced 4 in one bath and 6 in another. I replaced 6 bulbs in a bedroom and 7 around the house for a total of like 28 bulbs. When I did this last year in my old apartment in November I saved over $110 over that bill the year before. I am estimating that I save about $1250 a year by moving to CFs.

A good rule of thumb for changing out an incandescent for a CF is to look for that equivalent CF that is 20% of the incandescent wattage. A 45W is now like a 9W CF, a 65W is like a 13W CF, a 100W is like a 20W CF and so on. You should be able to get just about any size CF for just about any use. I even saw a “Black Light” CF for Halloween last week.

Prices right now for CF are generally higher than for incandescent bulbs unless they are on sale and that is often now that production is ramping up for CFs. Also, you can sometimes get rebates and coupons from your power company to help you make the switch. But your biggest draw should be the simple fact that these bulbs use 1/5th the power of incandescent bulbs and you will likely see the savings in your very next power bill (or the one after for sure). Usually one month savings is enough to save you more than you spent to put in the new lights.

There is one other consideration that comes with changing out bulbs like this, the average life of the bulb. Your standard incandescent will last somewhere between 1000 to 2000 hours and then need be replaced. The new CFs average life is about 8000 to 12000 hours.  Even if every CF bulb was like $8.00 you would still be cheaper to buy CFs, by a lot.

Most of the packaging for CF bulbs say they last for 5 to 7 years or more. I have yet to see that, but I have burned out a few CFs. I have found that CFs do not do well with power spikes. So, my only word of advice is to install a few of them and see how they work for you. I still think you should just replace them all, even if a few go bad the savings will be worth it.

I don’t know what the savings over the life of each bulb would be, it would vary with your power costs, but it has to be significant. And with those saving you may want to consider even better lighting by moving up to higher temperature CFs.

Why higher temperature bulbs?

Here it is in a nutshell, the higher the number in Kelvins (K) the bulb the more colors are visible. If you want your décor to look better, the colors to pop more go for some of the higher temperature bulbs. With the prices dropping and our understanding increasing it should be obvious that these lights are just plain better. If you use standard 2800K bulbs for everything else, use a 3400K bulb for a reading light, it will make it easier. If you use spots for art work or such, use a 4800K or 5400K to make the colors read true and pop more.

There is one additional reason to use a very high temperature bulb (5800K and 6400K) and that is for those with SAD (Seasonal Affective Disorder). During the winter these people suffer undue depression simply because there is not enough daylight. By using these “daylight” bulbs you can help SAD sufferers cope with this waning light. I know, I have seen it work with a family member. Considering the prices are coming down so fast and these bulbs, usually very short lived are lasting even longer, there should be no reason not to have better quality light in your home.

The Future of the Light Bulb

High Power Light Emitting Diodes are the next stage of light bulb technology. Already, HPLED or just LEDs, are being used for lasers, flashlights, public traffic lights and other uses where very long life is needed. These are also used where a very small light is needed. They work simply by conducting and electrical charge across a gap from an anode to a cathode. The higher charged electron on the anode falls to a ground state on the cathode (into a “hole”) and in the process emits a photon. If this all sounds like quantum physics you are right. They require a heat sink (usually under the LED) and use about the same power as the CFs. The difference is they can last a VERY long time, like 30,000 to 50,000 hours or even more. Also, depending on the elements used the color and temperature can be just about anything. The new “white” LEDs work by creating a blue light that shines on to a phosphor making pure white light.

The prices for these lights are very high, but if you have the money to invest $30 to $60 per bulb it may be worth switching to now and not having to deal with your bulbs for 15 years or more. And since they use only 1/5 the power of incandescent bulbs the cost could be paid off very quick. I am considering replacing one bulb a month until they are all replaced.

It Isn’t Easy Being Green

All bulbs should be disposed of properly. Incandescent, Fluorescent, and LED bulbs all use rare elements that should not be simply put into a trash can and dumped. You should hold on to used bulbs until your community has a “hazardous waste round-up” (usually once a year) and drop them off there. You will get the satisfaction of knowing that you are doing the environmentally correct thing. Also, since these new bulbs last so long they generate less pollution and waste. All this is good and green, you just have to do it and reap the huge savings on your power bill. And hey, while you are saving on your power bill you are drawing less electricity and lowering your carbon emissions used to generate your electricity. Wow, it really can be one big green world and we can all save some hard earned cash!

One other little side effect for those that like to use a lot of lights in their homes; the CFs and LEDs generate a lot less heat and therefore you also save on your cooling bill. You may not believe it can really make a difference, but the incandescent bulbs get really hot. This should be something you really should consider.

When you move, and most of us will move at one time or another, leave the CFs as an example for the new people who will occupy your home. Or, if you have splurged for LED lights and the prices have not dropped considerably, pull all your LEDs and take them with you and save a bundle on replacement cost. The long life of the LEDs make taking them with you reasonable.

I hope this has shed a little light on light bulbs.