News Analysis

GU24: New Pin-Base for CFLs, LEDs

Most compact fluorescent lamps (CFLs) still use screw bases, making them interchangeable with incandescent lamps. With those old lamps still 75% cheaper, on average, than the more efficient CFLs, it’s common for occupants to substitute them for CFLs. In addition to compromising energy savings, this also undermines utility incentive programs, which often subsidize CFLs, only to have them replaced at the end of their lives with incandescents.

In 2008 the California Energy Commission issued a rule under Title 24 requiring high-efficiency lighting on all residential remodels and new construction. Title 24 defines high-efficiency lighting based on the rating of the socket, stating in the rule: “A high efficacy lamp screwed into a low efficacy luminaire [Edison socket] will still be considered to be a low efficacy lighting system for Title 24 projects.” In other words, only pin-based sockets such as the GU24 fixtures are considered high-efficiency and are permissible.

Published October 5, 2011

Dick, E. (2011, October 5). GU24: New Pin-Base for CFLs, LEDs. Retrieved from