Mother Nature Network reports that Zero Energy Technology and Architecture (ZETA) of San Francisco is building Tierra del Sol, a net-zero energy community of 22 modular homes in Stockton, California.  Each 1,268 square foot home is designed to save the residents $2,000 annually on utility expenses.  A project funded jointly by non-profits and government, it is ZETA’s largest so far, and will generate 50 jobs.  The homes all have super-efficient heating, cooling and water systems, stainless steel Energy Star appliances, and are aimed at the affordable housing market.  ZETA offers workers the opportunity to buy the house they have helped to build through an employee assistance program.