This document introduces the Thousand Home Challenge, which aims to reduce energy consumption in existing homes by 70-90% through performance-based design. It reviews two options for qualifying homes in the challenge - reducing energy use by 75% or meeting a customized energy threshold. The document also provides a case study of a 1940 home in Petaluma, CA that was rehabilitated in phases to incorporate various energy efficiency and renewable energy strategies, with the goal of achieving net zero energy use.