When not in use turn off the juice
These quick tips from the Port of Skagit, one of the nine agencies that Ric Boge works with as a shared resource conservation manager, are good advice anywhere.
Question: Is it better to leave lights on while you are out for short periods of time because the life of the light is shortened every time they are tuned on and off?
Answer: All types of lights have a nominal or rated operating life, which is the total number of hours that they will provide a specified level or amount of light. You are correct that the operating life of all types of light bulbs is affected by how many times they are turned on and off. However, the exact number of hours that switching lights on and off reduces the total operating life, depending on the type of light, how many times it is switched on and off, and the price of electricity.
Some basic rules:
Incandescent lights should be turned off whenever they are not needed. Nearly all types of incandescent light bulbs are fairly inexpensive to produce and are relatively inefficient. Only about 10 to 15 percent of the electricity that incandescent lights consume results in light—the rest is turned into heat. So turning the light(s) off will keep a room cooler, an extra benefit in the summer. Therefore, the value of the energy saved by not having them on will be far greater than the cost of having to replace the bulb.
For fluorescent lights, if you leave a room for more than 15 minutes it is probably more cost effective to turn them off. Fluorescent lights are more expensive to buy, and their operating life is more affected by the number of times they are switched on and off , relative to incandescent lights. Therefore, it is a cost trade-off between saving energy and money by turning a light off “frequently” and having to replace the bulbs “more” frequently.
Question: I thought that fluorescent lights use a lot of energy to get started, and thus it is better not to turn them off for “short” periods. Is this true?
Answer: There is an increase in power demand when a light is switched on called an “in rush.” The exact amount of in rush depends on the type of ballast and lamp. However, the amount of electricity consumed to supply the inrush current is equal to a few seconds or less of normal light operation. So turning off fluorescent lights for more than 5 seconds will save more energy than will be consumed in turning them back on again.