This calculator lets you see how much you could save - dollars and energy - by using high-efficiency fluorescent lights instead of the old standard incandescent bulbs. Or, if you already use the fluorescent, you can find out how much you are already saving.
If you don't like reading instructions, click here to go to the calculator page. Otherwise, read the next section, at least.
1. Make a list of your current lighting usage
The easiest way is to walk around your home or office with a pad of paper. For each incandescent light, write down: (1) the wattage of the bulb; (2) the number of bulbs; (3) the approximate number of hours per day that the light is on.
2. Enter your usage data into the calculator
Enter the data you have gathered into the calculator table. Click in a cell to enter a number; you can tab to the next field. Be sure to hit tab or click in another cell after you make your last entry.
As you make each entry, the calculator will display the suggested fluorescent replacement for the "standard" (incandescent) bulb you have entered.
The table has 9 rows; if you need more space to enter your usage, you can combine data. For example, you could combine a 60 watt bulb in the kitchen that is on for 4 hours per day and a 60 watt porch light that is on for 6 hours per day into one 60 watt bulb that is on for (4 hours + 6 hours =) 10 hours per day. Only combine bulbs with the same wattage; don't combine two 30 watt bulbs into one 60 watt bulb.
3. Check your results
The Results section will tell you how much electricity you currently use and how much the suggested replacements would use. It also indicates how much you will save because fluorescents last much longer than standard bulbs. Finally, it will tell you your estimated yearly savings if you replace your standard bulbs with the suggested high-efficiency fluorescents.
4. Fine tune the base costs
The calculations are based on a number of factors: your electric power rates, the costs of standard and fluorescent light bulbs, and the expected lifetimes of standard and fluorescent light bulbs. These factors are listed in the Base Costs table at the end of the calculator page.
If you live in San Diego and get power at standard SDG&E residential rates, purchase normal (not long-life) standard bulbs and purchase fluorescent bulbs supported by the local rebate program (easy to do - shop at Home Depot or a number of other outlets), then the results displayed are pretty close to what you can expect to save.
If any of these Base Costa are not correct, you can change them. For example:
- If you don't live in San Diego, you will certainly have to adjust your cost of electric power; the rate is probably shown on your electric bill.
- If you don't have a local program for rebates or cost reduction, your costs for high-efficiency fluorescent lights will almost certainly be higher, and you can enter a new price and/or lifetime. Shop around - the price for these bulbs can easily vary by a factor of two or three.
- If you use long-life standard bulbs, enter a new cost and lifetime.
Be sure to press "tab" or click any other cell after you make your last entry in the Base Costs table. Then, check your new Results.
Click Here to go to the calculator
When I first heard about the new fluorescents, I wasn't interested: they conjured up images of the cold, flickery blue-toned light from the old fluorescent tubes. I hate the light from those 4-foot-long monsters.
So it was with some skepticism that I tried one of the new units I received as a gift. What a surprise! The light was warm-toned, virtually indistinguishable from the incandescents. I proceeded to replace all the lights in my home and office. As a bonus, the lower energy requirements meant that my office stayed a lot cooler.
The next surprise came about two years later when I finally had to replace one of them and realized that I hadn't replaced a bulb for a long time. Now, three years later plus, I am replacing more of the units, but many of them are still going strong. A number of units from 1995 are still running strong in 2008 but I wouldn't count on that long a life!
The final bonus can when I used the calculator to see just how much I was saving, and discovered that I had probably saved $1,500 or more over the three years.
So, what are you waiting for?
-- Chris Klein