From the Cambridge Energy Alliance, on March 6, 2018: Residents can exchange up to three incandescent or CFL lightbulbs for LED lightbulbs at upcoming events this spring. The Alliance-hosted swaps, starting Saturday, are free and open to all Cambridge residents:

bullet-gray-small March 17 from 10 a.m. to 1 p.m. at the Cambridge Winter Farmers Market, in the Cambridge Community Center, 5 Callender St., in the Riverside neighborhood.

bullet-gray-small April 20 from noon to 3 p.m. at the Cambridge Science Festival at City Hall, 795 Massachusetts Ave., Central Square.

bullet-gray-small May 19 from noon to 2 p.m. at the Cambridge Bicycle Committee Spring Ride post-ride celebration at the Cambridge Main Library, 449 Broadway, Mid-Cambridge.

bullet-gray-small June 2 from 11 a.m. to 6 p.m. at the Cambridge River Festival at Lechmere Canal Park, East Cambridge.

The events will offer standard A19 LEDs, which fit most lamps and fixtures, and BR30 LEDs, typically used for recessed lighting. Exchanges are limited to three bulbs per household to ensure supply for all participants. LED bulbs use five to six times less energy than incandescent bulbs and 40 percent less energy than CFL bulbs. In addition to long-term financial savings, LED bulbs are mercury-free and can last up to 20 years.

“Lightbulb swaps are a great example of how simple home improvement changes can result in energy savings,” said said Iram Farooq, assistant city manager for community development. “We look forward to building on the success of last year’s event, which exchanged hundreds of bulbs in a single afternoon, by providing more opportunities for the community to access energy efficient resources.”