Ask the Expert

Save money through lighting

Q: We're starting to think more about energy efficiency and how to save money on home-related expenses. What are some ways to reduce our energy consumption costs through lighting?

Did you know a 60-watt incandescent light bulb, left on for four hours per day over the course of a year (at 20 cents per kilowatt hour), will cost $17.47 per year? Now compare that to a 10-watt, 800-lumen LED bulb that puts out the same amount of light and will only cost you $2.91. That is a savings of $14.56 for every light bulb left on for only four hours per day for a year!

Another way to look at it: If you replace a 100-watt incandescent bulb (1600 lumens) with a 20-watt LED bulb (also 1600 lumens), that is a whopping 8-percent savings on your lighting bill every month!

LED bulbs will cost a little more upfront, but they last 25 times longer than the old incandescent bulbs. LED bulbs can last up to 25,000 hours but your incandescent bulbs only last up to 800 hours.

Here are some helpful tips when purchasing LED light bulbs:

First, look for the lumens on the box. Lumens are the amount of light output.

• 800 lumens equals the same amount of light as a 60-watt light bulb
• 1600 lumens equals the same amount of light as a 100-watt light bulb

Another important consideration when buying light bulbs is the “color” or “temperature” of the light. If you like the light of an incandescent light bulb, look for a color temperature of 2700K – 2800K. This is a warm, soft white color. A 3000K bulb is a whiter light and 4000K-5000K is similar to daylight.

• Brightness = lumens
• Color = temperature

In my own home, I had 4000K LED bulbs in the bathroom. I loved them so much, I decided to replace my living room bulbs with 4000K LED bulbs. As soon as I turned on the lights, I knew I had made a mistake. My living room reminded me of a bright, sterile operating room. I quickly learned about color “temperature.” The daylight bulbs worked well in a bathroom or kitchen, but when watching TV or visiting with company, the warmer 2800K bulbs work best.

Betty Hall is AHFC’s Energy Information Specialist and teaches a monthly 2-hour free class – the Secrets & Science of Energy Efficiency. Betty manages AHFC’s Research Information Center, which is a building science library available to the public by appointment. Visit