Replacing energy-hogging incandescents with energy-saving fluorescents (CFLs) is a simple, effective way to slow the rate of global climate change while saving money.  It’s good for the environment, it’s economical, it’s efficient, and it’s easy.

Why do it – Energy Savings

Cost - How much does it cost to run a light bulb? - Are CFLs worth it?

Incandescent bulbs waste 90 percent of their energy generating heat.   The "fuel" efficiency of a CFL is like replacing a car that gets 20 miles per gallon with one that gets 100 miles per gallon.

Replacing incandescent bulbs with CFLs lower the electrical bill for lighting up to 75%.   If you replaced 20 75-watt incandescent bulbs with 23-watt CFLs, you would save 1,040 watts for every hour that the lamps burned.   At five hours per day, this means saving over 2,000 kWh or about $208 back in your pocket every year.   (Replace them with a 20-watt CFL and save more – but slightly less light.) 

If you know the wattage of any electrical device, you can figure out the cost with this formula:

You can get your cost per kilowatt hour (kWh) from your utility bill.   Many of Michiganresidents pay between $0.075 (7.5 cents) and $0.097 (9.7 cents) per kWh.   The rate may change from winter to summer. 

Example:

A 75 watt incandescent lamp; run 2000 hours; at a rate of .10/kWh = average cost per year

A 23 watt CFL bulb (same or better light than the 75 watt incandescent); run 2000 hours; at a rate of .10/kWh = average cost per year

If the CFL bulb cost less than $10, the energy savings paid for it in the first year but the energy savings continue for the rest of its life - four or more years – and go in your pocket.  If there are labor costs related to replacing the bulbs, these are also saved.  The longer life CFL means up to 10 fewer light bulb changes.

* Based on 8,000-hour CFL life and 750-hour incandescent life and 10 cents per kWh.   If you want to compare the longer life incandescents, drop the watts on the CFL to 20 as the longer life incandescents provide less lumens.  The savings may be even greater.

   * NOTE: When comparing incandescent or halogen bulbs to fluorescent, compare the light output, or lumens, and not watts.    Wattsequal the energy used, not the amount of light.

* Generally if the CFL cost less than $10, the first year’s energy savings pays for the light bulb.  That’s a better return on investment than seen in most other programs, including stocks.

Cooling Costs

One additional area of potential savings is cooling.  Ninety percent of the energy used by incandescents generates heat, to heat the filament in order to produce light.  By replacing them, there will be less need for cooling the heat they generated during the summer season.

Your own Costs

If you want to determine your own costs, use the calculator on the website or have a copy of the excel spreadsheet sent to you.