Thomas Siebel, a technology entrepreneur and chairman of the Thomas and Stacey Siebel Foundation, said today he plans to establish a $20-million prize to encourage the creation of affordable energy-efficient homes.

Mr. Siebel, whose foundation is best known for its efforts to prevent methamphetamine use, told an audience at the Global Philanthropy Forum that he has been working for two years with researchers at Stanford, Princeton, and other institutions on the project.

While it’s possible today to build homes that have zero energy footprint, Mr. Siebel said, it’s an incredibly costly task. By contrast, the philanthropist said, he wants to support the development of energy-efficient homes that are no more expensive to build than ordinary houses.

Mr. Siebel said he plans to officially announce the prizes this fall. The awards will be given out in three phases: first, for the development of ways to reduce to zero the energy footprint of homes; second, for the design of houses that use that technology; and third, for the construction of the 10 types of homes that show the most promise.

The home that performs the best, he said, will be awarded $10-million. Mr. Siebel said he would support the construction of a 100-home energy-free community based on the winning designs on the campus of the University of Illinois at Urbana.