On May 3 and 4, the Homebuilders Assoication of Durham, Orange and Chatham Counties will host its third annual Green Homes Tour, a self-guided tour of about 40 homes built with energy efficiency and environmental responsibility in mind. Participants may see what local builders are incorporating in the pursuit of sustainability. The tour lasts from 10 a.m. to 6 p.m. Saturday and noon to 6 p.m. Sunday.

The weekend includes a kickoff event at the NC Biotechnology Center in Research Triangle Park, with speaker Larry Shirley and others. The event lasts from 9 a.m. to around noon. For information see www.hbadoc.com.