Although, from an energy consumption perspective, almost any compact fluorescent light (CFL) is better than the incandescent bulb it replaces, some CFLs are better than others. A recent report from the Environmental Working Group has identified a long list of over 1000 models of CFL bulbs that fail the 2008 standards.
More than 3,000 light bulbs qualify for the Energy Star logo under current standards,issued in 2003. But 1,100 of these bulbs do not meet the 2008 Energy Star standards for energy efficiency. The reason: the Department of Energy has postponed the effective date of the 2008 standards to July 1, 2009, giving the bulb industry a 6-month “grace period,” to sell a 100 million bulb inventory that has backed up because of the economic slowdown.
On the other hand, the same report also includes a list of their most favorably rated CFL bulbs in a Green Light Guide. Many of the bulbs in the guide have less than 2mg of mercury, versus an average of 4 milligrams for all CFLs.