Terryorisms

Leave Fluorescent Lights Off Or On? March 27, 2008

Does Turning Fluorescent Lights Off Use More Energy Than Leaving Them On?: Scientific American

The thinking is that the boost of energy such bulbs require to power up means that it might be best to keep them on when leaving a room, rather than subjecting them to the stress of a restart on your return.
Turns out, however, that power surge is so brief that its energy draw doesn’t amount to much: the equivalent of a few seconds or so of normal operation, according to U.S. Department of Energy estimates.

A simple rule of thumb that balances both concerns is to shut off fluorescents if you’re planning to leave a room for more than five minutes, according to Francis Rubinstein, a staff scientist in the Building Technologies Department at Lawrence Berkeley National Laboratory’s Environmental Energy Technologies Division.

Rubinstein notes that, even for fluorescents, the cost of electricity over a bulb’s lifetime far outpaces the cost of the bulb itself. “Even if you switch on and off a fluorescent light frequently,” he says, “the slight reduction in lamp life is a small effect relative to the energy savings you accomplish by being a good citizen.”