Light bulb classes A through G are designations of energy efficiency used by the European Union (EU). Bulbs classified as "A" are the most energy-efficient light bulbs available. The designation is similar to the "EnergyStar" label rating system in the United States. Do not use European light bulbs in U.S. fixtures, because the voltage may not be compatible with U.S. household electrical current.
European light bulb classes define how much energy a bulb uses compared to a standard incandescent bulb with a tungsten filament. Tungsten bulbs produce relatively high amounts of heat, which is essentially wasted energy, as it does not contribute to visible light. Class A bulbs use only 20 to 50 percent of the energy consumed by an incandescent light bulb of similar brightness. For example, to achieve class A rating, a light bulb as bright as a 60-watt incandescent must consume between 12 and 30 watts per hour.
Class A light bulbs use compact fluorescent (CFL), halogen or LED technology to provide bright light without consuming much energy. LEDs tend to consume the least amount of energy, followed closely by CFL bulbs. Halogen lamps are closer to tungsten technology but use halogen gasses within the glass to increase brightness and energy efficiency.
Mandated Energy Efficiency
From 2009 to 2016, the EU is phasing out inefficient light bulbs in favor of energy-efficient varieties. This will affect class D and lower bulbs of certain types. As of 2011, all light bulbs with the equivalent brightness of a 60-watt or brighter lamp must meet class A, B or C regulations. The EU commission will review the regulations in 2014, but plans to move toward the goal of requiring most light bulbs to achieve class A or B status by 2016.
Beware of confusing class A European light bulbs with type A light bulbs. Type A is a U.S. designation for standard incandescent bulbs with medium screw-in bases, such as those found in most homes prior to CFL technology. Type A light bulbs are not energy-efficient, because most use tungsten filament technology.