Urban myths - stuff you know, but don't really know why or from where you learnt it - abound in many daily activities, including energy use.
The first of the myths we'd like to explore is: you should leave your lights on when you leave the room, to save energy (and money).
Busted - for two of the types of lighting covered in this article. For the new and more efficient CFLs, you can relax a tad more.
According to the www.energy.gov website, it's not as simple as turning the switch off. It depends on the type of bulb you have in your home and the cost per kWh (kilowatt hour) of your electricity. Also some lightbulbs wear out faster than others, reducing their light-giving life the more often they are switched on and off.
See below for rules of thumb for three lighting types: incandescent, halogen or compact fluorescent lighting (CFLs).
Fact: turn off Incandescent lights whenever they are not needed.
These are the least efficient type of lighting - giving off 90 per cent of the energy as heat and only about 10 per cent as light. Turning lights off will also keep a room cooler, an extra benefit in summer.
Fact: turn off halogen lights whenever they are not needed.
While halogens are more efficient than traditional incandescent bulbs, they use the same technology and are far less efficient than compact fluorescent lighting (CFLs) and LEDs.
You can relax with these guys; the CFLs are already energy efficient. As a guide, turn them off if you will be out of room for more than 15 minutes.