Governments, measurements, and CFLs

September 1^st marked the beginning of the phase-out of the incandescent bulb in European Union countries. Intrepid reporters at the British newspaper, the Telegraph, decided not to trust the packaging information on CFLs claiming the enclosed 12W CFL had the equivalent light output of a 60W incandescent. The Telegraph reported that, when measured with a hand-held light meter placed half a meter away from the test light bulb in an otherwise-darkened room, that a frosted 60W measured 101 lux, while a 11W CFL made by General Electric and handed out free to a local utility’s customers measured only 79 lux.

(The European Union’s FAQ page for the phase-out of incandescents agrees that CFL packaging claims of equivalency to 60W incandescent are wrong, but points out that you don’t have to go up too much in CFL power to gain more output: “The light output of 15W compact fluorescent lamp is slightly more than the light output from a 60W incandescent.")

One of the Qs on the FAQ page is, “Do we have to measure the strength of light in lumens instead of watts?”  The page explains that Watts measures the power consumed by the device, while lumens measures the total light produced by the device. To further confuse EU citizens, the light meter used by the Telegraph reporters gives light measurements in lux, not lumens. (Lux is a measurement of light per square meter on a surface. Measuring lumens requires a sophisticated light measurement integrating sphere that measures the total light emitted by a device.) For consistency in comparing light output, the EU requires the bulbs be labeled with both Watts consumed and lumens produced.

Here’s a quote from the Telegram article: “Syed Kamall, the Conservative MEP who has campaigned against European interference in traditional measures, said the new regulations would create confusion among consumers. He said: "While lumens measure brightness, no one I have met understands these units." (italics inserted.)

So as a public service I am linking to this excellent free handbook on measuring light, The Light Measurement Handbook by Alex Ryer. Or, search for it on the Web and you’ll find several places where you can download the pdf.  (Hat tip to Doug Leeper for sending me the pdf.)

The problems that the EU is experiencing with regulating the adoption of CFLs should serve as a cautionary tale for the LED lighting industry about setting consumer expectations.

Continue the discussion about high-brightness LEDs in the real world: Attend EDN’s free one-day “Designing with LEDs” Workshop in Chicago on October 6. Register now.