AUSTIN (KXAN) — Four east Austin families got keys to their brand new, energy-efficient homes on Saturday.

Congressman Lloyd Doggett and Mayor Steve Adler showed up to dedicate the first ever Austin Habitat Net Zero homes to the families.

The energy-efficient homes produce as much renewable energy as they consume over the course of one year. Occupants are also said to have a net zero energy bill and a carbon-free home.

Austin Habitat for Humanity and Guadalupe Neighborhood Development Corporation partnered up last January for the project. It’s part of an effort to create more stability and affordability in the city’s housing market.