Down to your last old-fashioned incandescent light bulb? Maybe it’s time to figure out the new energy-saving light bulbs. The standard Thomas Edison incandescent light bulb is extremely inefficient, wasting about 90% of its energy as heat rather than light. As part of a federal law passed in 2007, increasing efficiency standards for light bulbs, the traditional bulbs have now been phased out. In 2012, the phase-out began with the 100-watt bulb, followed by the 75-watt in 2013, and the 60-watt and 40-watt in 2014. But which bulb do you want or need? We’ve put together a primer of factors to consider when replacing traditional bulbs. Read all about it on our sister site, Living on the Cheap.